const EPSILON14 = 0.00000000000001;
const EPSILON15 = 0.000000000000001;
const PI_OVER_TWO = Math.PI / 2.0;
const SHIFT_LEFT_12 = Math.pow(2.0, 12.0);
const TerrainQuantization = {
    NONE: 0,
    BITS12: 1
}
const maxShort = 32767;
const halfMaxShort = (maxShort / 2) | 0;

function defined(target) {
    return target !== undefined && target !== null;
}

function defaultValue(value, defaultValue) {
    if (!defined(value)) return defaultValue;
    return value;
}

function lerp(p, q, time) {
    return (1.0 - time) * p + time * q;
  };
function clamp(value, min, max) {
    return value < min ? min : value > max ? max : value;
};
  
function equalsEpsilon(a, b, epsilon) {
    return Math.abs(a - b) <= epsilon;
}

function sign(a) {
    if (a == 0) return 0;
    return Math.abs(a) === a ? 1.0 : -1.0;
}

function fromSNorm(value, rangeMaximum) {
    rangeMaximum = defaultValue(rangeMaximum, 255);
    return (clamp(value, 0.0, rangeMaximum) / rangeMaximum) * 2.0 - 1.0;
}

function signNotZero(value) {
    return value < 0.0 ? -1.0 : 1.0;
}

function mod(m, n) {
    if (sign(m) == sign(n) && Math.abs(m) < Math.abs(n)) return m;
    return ((m % n) + n) % n;
}

function zeroToTwoPi(angle) {
    if (angle >= 0 && angle <= Math.PI * 2) {
        return angle;
    }
    const modr = mod(angle, Math.PI * 2);
    if (
        Math.abs(modr) < EPSILON14 &&
        Math.abs(angle) > EPSILON14
    ) {
        return Math.PI * 2;
    }
    return modr;
}

function negativePiToPi(angle) {
    if (angle >= -Math.PI && angle <= Math.PI) {
        return angle;
    }
    return zeroToTwoPi(angle + Math.PI) - Math.PI;
}

function scaleToGeodeticSurface(
    cartesian,
    oneOverRadii,
    oneOverRadiiSquared,
    centerToleranceSquared,
    result
) {
    const positionX = cartesian.x;
    const positionY = cartesian.y;
    const positionZ = cartesian.z;

    const oneOverRadiiX = oneOverRadii.x;
    const oneOverRadiiY = oneOverRadii.y;
    const oneOverRadiiZ = oneOverRadii.z;

    const x2 = positionX * positionX * oneOverRadiiX * oneOverRadiiX;
    const y2 = positionY * positionY * oneOverRadiiY * oneOverRadiiY;
    const z2 = positionZ * positionZ * oneOverRadiiZ * oneOverRadiiZ;

    // Compute the squared ellipsoid norm.
    const squaredNorm = x2 + y2 + z2;
    const ratio = Math.sqrt(1.0 / squaredNorm);

    // As an initial approximation, assume that the radial intersection is the projection point.
    const intersection = Vector3.multiplyByScalar(
      cartesian,
      ratio
    );

    // If the position is near the center, the iteration will not converge.
    if (squaredNorm < centerToleranceSquared) {
      return !isFinite(ratio)
        ? undefined
        : result.copy(intersection);
    }

    const oneOverRadiiSquaredX = oneOverRadiiSquared.x;
    const oneOverRadiiSquaredY = oneOverRadiiSquared.y;
    const oneOverRadiiSquaredZ = oneOverRadiiSquared.z;

    // Use the gradient at the intersection point in place of the true unit normal.
    // The difference in magnitude will be absorbed in the multiplier.
    const gradient = new Vector3();
    gradient.x = intersection.x * oneOverRadiiSquaredX * 2.0;
    gradient.y = intersection.y * oneOverRadiiSquaredY * 2.0;
    gradient.z = intersection.z * oneOverRadiiSquaredZ * 2.0;

    // Compute the initial guess at the normal vector multiplier, lambda.
    let lambda =
      ((1.0 - ratio) * cartesian.length()) /
      (0.5 * gradient.length());
    let correction = 0.0;

    let func;
    let denominator;
    let xMultiplier;
    let yMultiplier;
    let zMultiplier;
    let xMultiplier2;
    let yMultiplier2;
    let zMultiplier2;
    let xMultiplier3;
    let yMultiplier3;
    let zMultiplier3;

    do {
      lambda -= correction;

      xMultiplier = 1.0 / (1.0 + lambda * oneOverRadiiSquaredX);
      yMultiplier = 1.0 / (1.0 + lambda * oneOverRadiiSquaredY);
      zMultiplier = 1.0 / (1.0 + lambda * oneOverRadiiSquaredZ);

      xMultiplier2 = xMultiplier * xMultiplier;
      yMultiplier2 = yMultiplier * yMultiplier;
      zMultiplier2 = zMultiplier * zMultiplier;

      xMultiplier3 = xMultiplier2 * xMultiplier;
      yMultiplier3 = yMultiplier2 * yMultiplier;
      zMultiplier3 = zMultiplier2 * zMultiplier;

      func = x2 * xMultiplier2 + y2 * yMultiplier2 + z2 * zMultiplier2 - 1.0;

      // "denominator" here refers to the use of this expression in the velocity and acceleration
      // computations in the sections to follow.
      denominator =
        x2 * xMultiplier3 * oneOverRadiiSquaredX +
        y2 * yMultiplier3 * oneOverRadiiSquaredY +
        z2 * zMultiplier3 * oneOverRadiiSquaredZ;

      const derivative = -2.0 * denominator;

      correction = func / derivative;
    } while (Math.abs(func) > CesiumMath.EPSILON12);

    if (!defined(result)) {
      return new Vector3(
        positionX * xMultiplier,
        positionY * yMultiplier,
        positionZ * zMultiplier
      );
    }
    result.x = positionX * xMultiplier;
    result.y = positionY * yMultiplier;
    result.z = positionZ * zMultiplier;
    return result;
}

class Vector3 {
    constructor (x,y,z) {
        this.x = x || 0;
        this.y = y || 0;
        this.z = z || 0;
    }

    static midpoint(left, right, result) {
        if (!defined(result)) result = new Vector3();
        result.set(
            (left.x + right.x) * 0.5,
            (left.y + right.y) * 0.5,
            (left.z + right.z) * 0.5,
        );
        return result;
    }

    static minimumByComponent(v1, v2, result) {
        if (!defined(result)) result = new Vector3();
        result.set(
            Math.min(v1.x, v2.x),
            Math.min(v1.y, v2.y),
            Math.min(v1.z, v2.z)
        )
        return result;
    }

    static maximumByComponent(v1, v2, result) {
        if (!defined(result)) result = new Vector3();
        result.set(
            Math.max(v1.x, v2.x),
            Math.max(v1.y, v2.y),
            Math.max(v1.z, v2.z)
        );
        return result;
    }

    static maximumComponent(v) {
        return Math.max(v.x, v.y, v.z);
    }

    static equals(v1, v2) {
        return (v1.x == v2.x &&
                v1.y == v2.x &&
                v1.z == v2.z);
    }

    static equalsEpsilon(v1, v2, epsilon) {
        return (Math.abs(v1.x - v2.x) <= epsilon &&
                Math.abs(v1.y - v2.y) <= epsilon &&
                Math.abs(v1.z - v2.z) <= epsilon        
            );
    }

    static unpack(array, startIndex, v) {
        v.x = array[startIndex];
        v.y = array[startIndex + 1];
        v.z = array[startIndex + 2];
    }

    static multiplyByScalar(v, scalar, result) {
        if (!defined(result)) result = new Vector3();
        result.x = v.x * scalar;
        result.y = v.y * scalar;
        result.z = v.z * scalar;

        return result;
    }

    static multiplyComponents(left, right, result) {
        if (!defined(result)) result = new Vector3();
        result.x = left.x * right.x;
        result.y = left.y * right.y;
        result.z = left.z * right.z;
        return result;
    }

    static divideByScalar(v, scalar, result) {
        if (!defined(result)) result = new Vector3();
        result.x = v.x / scalar;
        result.y = v.y / scalar;
        result.z = v.z / scalar;
        return result;
    }

    static subtract(left, right, result) {
        if (!defined(result)) {
            result = new Vector3();
        }

        result.set(
            left.x - right.x,
            left.y - right.y,
            left.z - right.z
        );
        return result;
    }

    static negate(v, result) {
        if (!defined(result)) {
            result = new Vector3();
        }

        result.set(
            -v.x, -v.y, -v.z
        );
        return result;
    }

    negate(){
        this.x = -this.x;
        this.y = -this.y;
        this.z = -this.z;
        return this;
    }

    static dot(left, right) {
        return left.x * right.x + left.y * right.y + left.z * right.z;
    }

    static cross(left, right, result) {
        if (!defined(result)) result = new Vector3();
        const leftX = left.x;
        const leftY = left.y;
        const leftZ = left.z;
        const rightX = right.x;
        const rightY = right.y;
        const rightZ = right.z;

        const x = leftY * rightZ - leftZ * rightY;
        const y = leftZ * rightX - leftX * rightZ;
        const z = leftX * rightY - leftY * rightX;

        result.x = x;
        result.y = y;
        result.z = z;
        return result;
    }

    clone() {
        return new Vector3(this.x, this.y, this.z);
    }

    static clone(source) {
        return new Vector3(source.x, source.y, source.z);
    }

    copy(source) {
        this.set(
            source.x, source.y, source.z
        )

        return this;
    }

    length() {
        return Math.sqrt(this.x * this.x + this.y * this.y + this.z * this.z);
    }

    lengthSquare() {
        return this.x * this.x + this.y * this.y + this.z * this.z;
    }

    normalize() {
        const length = this.length() || 1;
        return Vector3.divideByScalar(this, length, this);
    }

    set(x, y, z) {
        this.x = x;
        this.y = y;
        this.z = z;
    }

    static add(left, right, result) {
        if (!defined(result)) result = new Vector3();
        result.set(
            left.x + right.x,
            left.y + right.y,
            left.z + right.z
        );
        return result;
    }

    static normalize(v, result) {
        if (!defined(result)) result = new Vector3();
        const length = v.length() || 1.0;
        return Vector3.divideByScalar(v, length, result);
        
    }

    static fromCartesian4(v) {
        return new Vector3(v.x, v.y, v.z);
    }

    
}

Vector3.ZERO = Object.freeze(new Vector3(0, 0, 0))

class Vector2 {
    constructor(x, y) {
        this.x = x || 0;
        this.y = y || 0;
    }

    set(x, y) {
        this.x = x;
        this.y = y;
    }
}

class Vector4 {
    constructor(x, y, z, w) {
        this.x = x || 0;
        this.y = y || 0;
        this.z = z || 0;
        this.w = w || 0;
    }
}

class Matrix4 {
    constructor(
        column0Row0,
        column1Row0,
        column2Row0,
        column3Row0,
        column0Row1,
        column1Row1,
        column2Row1,
        column3Row1,
        column0Row2,
        column1Row2,
        column2Row2,
        column3Row2,
        column0Row3,
        column1Row3,
        column2Row3,
        column3Row3
    ) {
        this[0] = defaultValue(column0Row0, 0.0);
        this[1] = defaultValue(column0Row1, 0.0);
        this[2] = defaultValue(column0Row2, 0.0);
        this[3] = defaultValue(column0Row3, 0.0);
        this[4] = defaultValue(column1Row0, 0.0);
        this[5] = defaultValue(column1Row1, 0.0);
        this[6] = defaultValue(column1Row2, 0.0);
        this[7] = defaultValue(column1Row3, 0.0);
        this[8] = defaultValue(column2Row0, 0.0);
        this[9] = defaultValue(column2Row1, 0.0);
        this[10] = defaultValue(column2Row2, 0.0);
        this[11] = defaultValue(column2Row3, 0.0);
        this[12] = defaultValue(column3Row0, 0.0);
        this[13] = defaultValue(column3Row1, 0.0);
        this[14] = defaultValue(column3Row2, 0.0);
        this[15] = defaultValue(column3Row3, 0.0);
    }
    static multiplyByPoint(matrix, cartesian, result) {
        if (!defined(result)) result = new Vector3();
        const vX = cartesian.x;
        const vY = cartesian.y;
        const vZ = cartesian.z;

        const x = matrix[0] * vX + matrix[4] * vY + matrix[8] * vZ + matrix[12];
        const y = matrix[1] * vX + matrix[5] * vY + matrix[9] * vZ + matrix[13];
        const z = matrix[2] * vX + matrix[6] * vY + matrix[10] * vZ + matrix[14];

        result.x = x;
        result.y = y;
        result.z = z;
        return result;
    }
    static inverseTransformation(matrix, result) {
        if (!defined(result)) result = new Matrix4();
        const matrix0 = matrix[0];
        const matrix1 = matrix[1];
        const matrix2 = matrix[2];
        const matrix4 = matrix[4];
        const matrix5 = matrix[5];
        const matrix6 = matrix[6];
        const matrix8 = matrix[8];
        const matrix9 = matrix[9];
        const matrix10 = matrix[10];

        const vX = matrix[12];
        const vY = matrix[13];
        const vZ = matrix[14];

        const x = -matrix0 * vX - matrix1 * vY - matrix2 * vZ;
        const y = -matrix4 * vX - matrix5 * vY - matrix6 * vZ;
        const z = -matrix8 * vX - matrix9 * vY - matrix10 * vZ;

        result[0] = matrix0;
        result[1] = matrix4;
        result[2] = matrix8;
        result[3] = 0.0;
        result[4] = matrix1;
        result[5] = matrix5;
        result[6] = matrix9;
        result[7] = 0.0;
        result[8] = matrix2;
        result[9] = matrix6;
        result[10] = matrix10;
        result[11] = 0.0;
        result[12] = x;
        result[13] = y;
        result[14] = z;
        result[15] = 1.0;
        return result;
    }

    static multiply(left, right, result) {
        if (!defined(result)) {
            result = new Matrix4();
        }

        const left0 = left[0];
        const left1 = left[1];
        const left2 = left[2];
        const left3 = left[3];
        const left4 = left[4];
        const left5 = left[5];
        const left6 = left[6];
        const left7 = left[7];
        const left8 = left[8];
        const left9 = left[9];
        const left10 = left[10];
        const left11 = left[11];
        const left12 = left[12];
        const left13 = left[13];
        const left14 = left[14];
        const left15 = left[15];

        const right0 = right[0];
        const right1 = right[1];
        const right2 = right[2];
        const right3 = right[3];
        const right4 = right[4];
        const right5 = right[5];
        const right6 = right[6];
        const right7 = right[7];
        const right8 = right[8];
        const right9 = right[9];
        const right10 = right[10];
        const right11 = right[11];
        const right12 = right[12];
        const right13 = right[13];
        const right14 = right[14];
        const right15 = right[15];

        const column0Row0 =
            left0 * right0 + left4 * right1 + left8 * right2 + left12 * right3;
        const column0Row1 =
            left1 * right0 + left5 * right1 + left9 * right2 + left13 * right3;
        const column0Row2 =
            left2 * right0 + left6 * right1 + left10 * right2 + left14 * right3;
        const column0Row3 =
            left3 * right0 + left7 * right1 + left11 * right2 + left15 * right3;

        const column1Row0 =
            left0 * right4 + left4 * right5 + left8 * right6 + left12 * right7;
        const column1Row1 =
            left1 * right4 + left5 * right5 + left9 * right6 + left13 * right7;
        const column1Row2 =
            left2 * right4 + left6 * right5 + left10 * right6 + left14 * right7;
        const column1Row3 =
            left3 * right4 + left7 * right5 + left11 * right6 + left15 * right7;

        const column2Row0 =
            left0 * right8 + left4 * right9 + left8 * right10 + left12 * right11;
        const column2Row1 =
            left1 * right8 + left5 * right9 + left9 * right10 + left13 * right11;
        const column2Row2 =
            left2 * right8 + left6 * right9 + left10 * right10 + left14 * right11;
        const column2Row3 =
            left3 * right8 + left7 * right9 + left11 * right10 + left15 * right11;

        const column3Row0 =
            left0 * right12 + left4 * right13 + left8 * right14 + left12 * right15;
        const column3Row1 =
            left1 * right12 + left5 * right13 + left9 * right14 + left13 * right15;
        const column3Row2 =
            left2 * right12 + left6 * right13 + left10 * right14 + left14 * right15;
        const column3Row3 =
            left3 * right12 + left7 * right13 + left11 * right14 + left15 * right15;

        result[0] = column0Row0;
        result[1] = column0Row1;
        result[2] = column0Row2;
        result[3] = column0Row3;
        result[4] = column1Row0;
        result[5] = column1Row1;
        result[6] = column1Row2;
        result[7] = column1Row3;
        result[8] = column2Row0;
        result[9] = column2Row1;
        result[10] = column2Row2;
        result[11] = column2Row3;
        result[12] = column3Row0;
        result[13] = column3Row1;
        result[14] = column3Row2;
        result[15] = column3Row3;
        return result;
    }

    static fromTranslation(translation, result) {
        if (!defined(result)) {
           return new Matrix4(
            1.0, 0.0, 0.0, translation.x,
            0.0, 1.0, 0.0, translation.y,
            0.0, 0.0, 1.0, translation.z,
            0.0, 0.0, 0.0, 1.0
           );
        }

        result[0] = 1.0;
        result[1] = 0.0;
        result[2] = 0.0;
        result[3] = 0.0;
        result[4] = 0.0;
        result[5] = 1.0;
        result[6] = 0.0;
        result[7] = 0.0;
        result[8] = 0.0;
        result[9] = 0.0;
        result[10] = 1.0;
        result[11] = 0.0;
        result[12] = translation.x;
        result[13] = translation.y;
        result[14] = translation.z;
        result[15] = 1.0;
        return result;


    }

    static fromRotationTranslation(rotation, translation, result) {
         translation = defaultValue(translation, Vector3.ZERO);

        if (!defined(result)) {
            return new Matrix4(
                rotation[0],
                rotation[3],
                rotation[6],
                translation.x,
                rotation[1],
                rotation[4],
                rotation[7],
                translation.y,
                rotation[2],
                rotation[5],
                rotation[8],
                translation.z,
                0.0,
                0.0,
                0.0,
                1.0
            );
        }

        result[0] = rotation[0];
        result[1] = rotation[1];
        result[2] = rotation[2];
        result[3] = 0.0;
        result[4] = rotation[3];
        result[5] = rotation[4];
        result[6] = rotation[5];
        result[7] = 0.0;
        result[8] = rotation[6];
        result[9] = rotation[7];
        result[10] = rotation[8];
        result[11] = 0.0;
        result[12] = translation.x;
        result[13] = translation.y;
        result[14] = translation.z;
        result[15] = 1.0;
        return result;
    }

    static fromScale(scale, result) {
          if (!defined(result)) {
            return new Matrix4(
                scale.x,
                0.0,
                0.0,
                0.0,
                0.0,
                scale.y,
                0.0,
                0.0,
                0.0,
                0.0,
                scale.z,
                0.0,
                0.0,
                0.0,
                0.0,
                1.0
            );
        }

        result[0] = scale.x;
        result[1] = 0.0;
        result[2] = 0.0;
        result[3] = 0.0;
        result[4] = 0.0;
        result[5] = scale.y;
        result[6] = 0.0;
        result[7] = 0.0;
        result[8] = 0.0;
        result[9] = 0.0;
        result[10] = scale.z;
        result[11] = 0.0;
        result[12] = 0.0;
        result[13] = 0.0;
        result[14] = 0.0;
        result[15] = 1.0;
        return result;
    }

    static clone(matrix, result) {
        if (!defined(result)) {
            return new Matrix4(
                matrix[0],
                matrix[4],
                matrix[8],
                matrix[12],
                matrix[1],
                matrix[5],
                matrix[9],
                matrix[13],
                matrix[2],
                matrix[6],
                matrix[10],
                matrix[14],
                matrix[3],
                matrix[7],
                matrix[11],
                matrix[15]
            );
        }

        result[0] = matrix[0];
        result[1] = matrix[1];
        result[2] = matrix[2];
        result[3] = matrix[3];
        result[4] = matrix[4];
        result[5] = matrix[5];
        result[6] = matrix[6];
        result[7] = matrix[7];
        result[8] = matrix[8];
        result[9] = matrix[9];
        result[10] = matrix[10];
        result[11] = matrix[11];
        result[12] = matrix[12];
        result[13] = matrix[13];
        result[14] = matrix[14];
        result[15] = matrix[15];
        return result;
    }

    static setTranslation(matrix, translation, result) {
        if (!defined(result)) result = new Matrix4();
        result[0] = matrix[0];
        result[1] = matrix[1];
        result[2] = matrix[2];
        result[3] = matrix[3];
      
        result[4] = matrix[4];
        result[5] = matrix[5];
        result[6] = matrix[6];
        result[7] = matrix[7];
      
        result[8] = matrix[8];
        result[9] = matrix[9];
        result[10] = matrix[10];
        result[11] = matrix[11];
      
        result[12] = translation.x;
        result[13] = translation.y;
        result[14] = translation.z;
        result[15] = matrix[15];
      
        return result;
    }

    static getColumn(matrix, index, result) {
        if (!defined(result)) result = new Vector4();
        const startIndex = index * 4;
        const x = matrix[startIndex];
        const y = matrix[startIndex + 1];
        const z = matrix[startIndex + 2];
        const w = matrix[startIndex + 3];

        result.x = x;
        result.y = y;
        result.z = z;
        result.w = w;
        return result;
    }
}

class Matrix3 {
    constructor(
        column0Row0,
        column1Row0,
        column2Row0,
        column0Row1,
        column1Row1,
        column2Row1,
        column0Row2,
        column1Row2,
        column2Row2
    ) {
        this[0] = defaultValue(column0Row0, 0.0);
        this[1] = defaultValue(column0Row1, 0.0);
        this[2] = defaultValue(column0Row2, 0.0);
        this[3] = defaultValue(column1Row0, 0.0);
        this[4] = defaultValue(column1Row1, 0.0);
        this[5] = defaultValue(column1Row2, 0.0);
        this[6] = defaultValue(column2Row0, 0.0);
        this[7] = defaultValue(column2Row1, 0.0);
        this[8] = defaultValue(column2Row2, 0.0);
    }

    clone() {
        return new Matrix3(
            this[0],
            this[3],
            this[6],
            this[1],
            this[4],
            this[7],
            this[2],
            this[5],
            this[8]
        );
    }

    static setColumn(matrix, index, cartesian, result) {
        if (!defined(result)) result = new Matrix3();
        result = matrix.clone();
        const startIndex = index * 3;
        result[startIndex] = cartesian.x;
        result[startIndex + 1] = cartesian.y;
        result[startIndex + 2] = cartesian.z;
        return result;
    }

    static multiplyByVector(matrix, cartesian, result) {
        if (!defined(result)) result = new Vector3();
        const vX = cartesian.x;
        const vY = cartesian.y;
        const vZ = cartesian.z;
      
        const x = matrix[0] * vX + matrix[3] * vY + matrix[6] * vZ;
        const y = matrix[1] * vX + matrix[4] * vY + matrix[7] * vZ;
        const z = matrix[2] * vX + matrix[5] * vY + matrix[8] * vZ;
      
        result.x = x;
        result.y = y;
        result.z = z;
        return result;
    }

    static multiplyByScale(matrix, scale, result) {
        if (!defined(result)) result = new Matrix3();
        result[0] = matrix[0] * scale.x;
        result[1] = matrix[1] * scale.x;
        result[2] = matrix[2] * scale.x;
        result[3] = matrix[3] * scale.y;
        result[4] = matrix[4] * scale.y;
        result[5] = matrix[5] * scale.y;
        result[6] = matrix[6] * scale.z;
        result[7] = matrix[7] * scale.z;
        result[8] = matrix[8] * scale.z;

        return result;
    }
}

Matrix3.ZERO = Object.freeze(
    new Matrix3(0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0)
);

class Rectangle {
    constructor(west, south, east, north) {
        this.west = west || 0;
        this.south = south || 0;
        this.east = east || 0;
        this.north = north || 0;
    }

    static clone(source) {
        return new Rectangle(
            source.west,
            source.south,
            source.east,
            source.north
        );
    }
}


class BoundingSphere {
    constructor(center, radius) {
        this.center = center || Vector3.ZERO;
        this.radius = radius || 0;
    }

    static center(rectangle, result) {
        if (!defined(result)) result = new Cartographic();
        let east = rectangle.east;
        const west = rectangle.west;

        if (east < west) {
            east += Math.TWO_PI;
        }

        const longitude = negativePiToPi((west + east) * 0.5);
        const latitude = (rectangle.south + rectangle.north) * 0.5;

        result.longitude = longitude;
        result.latitude = latitude;
        result.height = 0.0;
        return result;
    }

    static fromPoints(positions, result) {
        if (!defined(result)) result = new BoundingSphere();

        if (!defined(positions) || positions.length === 0) {
            result.center.copy(Vector3.ZERO);
            result.radius = 0.0;
            return result;
        }
    
        const currentPos = new Vector3().copy(positions[0]);

        const xMin = currentPos.clone();
        const yMin = currentPos.clone();
        const zMin = currentPos.clone();

        const xMax = currentPos.clone();
        const yMax = currentPos.clone();
        const zMax = currentPos.clone();

        const numPositions = positions.length;
        let i;
        for (i = 1; i < numPositions; i++) {
            currentPos.copy(positions[i])

            const x = currentPos.x;
            const y = currentPos.y;
            const z = currentPos.z;

            // Store points containing the the smallest and largest components
            if (x < xMin.x) {
                xMin.copy(currentPos);
            }

            if (x > xMax.x) {
                xMin.copy(currentPos);
            }

            if (y < yMin.y) {
                yMin.copy(currentPos);
            }

            if (y > yMax.y) {
                yMax.copy(currentPos);
            }

            if (z < zMin.z) {
                zMin.copy(currentPos);
            }

            if (z > zMax.z) {
                zMax.copy(currentPos);
            }
        }

        // Compute x-, y-, and z-spans (Squared distances b/n each component's min. and max.).
        const xSpan = Vector3.subtract(xMax, xMin).lengthSquare();
        const ySpan = Vector3.subtract(yMax, yMin).lengthSquare();
        const zSpan = Vector3.subtract(zMax, zMin).lengthSquare();

        // Set the diameter endpoints to the largest span.
        let diameter1 = xMin;
        let diameter2 = xMax;
        let maxSpan = xSpan;
        if (ySpan > maxSpan) {
            maxSpan = ySpan;
            diameter1 = yMin;
            diameter2 = yMax;
        }
        if (zSpan > maxSpan) {
            maxSpan = zSpan;
            diameter1 = zMin;
            diameter2 = zMax;
        }

        // Calculate the center of the initial sphere found by Ritter's algorithm
        const ritterCenter = new Vector3();
        ritterCenter.x = (diameter1.x + diameter2.x) * 0.5;
        ritterCenter.y = (diameter1.y + diameter2.y) * 0.5;
        ritterCenter.z = (diameter1.z + diameter2.z) * 0.5;

        // Calculate the radius of the initial sphere found by Ritter's algorithm
        let radiusSquared = Vector3.subtract(diameter2, ritterCenter).lengthSquare();
        let ritterRadius = Math.sqrt(radiusSquared);

        // Find the center of the sphere found using the Naive method.
        const minBoxPt = new Vector3();
        minBoxPt.x = xMin.x;
        minBoxPt.y = yMin.y;
        minBoxPt.z = zMin.z;

        const maxBoxPt = new Vector3();
        maxBoxPt.x = xMax.x;
        maxBoxPt.y = yMax.y;
        maxBoxPt.z = zMax.z;

        const naiveCenter = Vector3.midpoint(minBoxPt, maxBoxPt);

        // Begin 2nd pass to find naive radius and modify the ritter sphere.
        let naiveRadius = 0;
        for (i = 0; i < numPositions; i++) {
            currentPos.copy(positions[i]);
            const r = Vector3.subtract(currentPos, naiveCenter).length();
            if (r > naiveRadius) {
                naiveRadius = r;
            }

            const oldCenterToPointSquared = Vector3.subtract(currentPos, ritterCenter).lengthSquare();
            
            if (oldCenterToPointSquared > radiusSquared) {
                const oldCenterToPoint = Math.sqrt(oldCenterToPointSquared);
                // Calculate new radius to include the point that lies outside
                ritterRadius = (ritterRadius + oldCenterToPoint) * 0.5;
                radiusSquared = ritterRadius * ritterRadius;
                // Calculate center of new Ritter sphere
                const oldToNew = oldCenterToPoint - ritterRadius;
                ritterCenter.x =
                (ritterRadius * ritterCenter.x + oldToNew * currentPos.x) /
                oldCenterToPoint;
                ritterCenter.y =
                (ritterRadius * ritterCenter.y + oldToNew * currentPos.y) /
                oldCenterToPoint;
                ritterCenter.z =
                (ritterRadius * ritterCenter.z + oldToNew * currentPos.z) /
                oldCenterToPoint;
            }
        }

        if (ritterRadius < naiveRadius) {
            result.center.copy(ritterCenter);
            result.radius = ritterRadius;
        } else {
            result.center.copy(naiveCenter);
            result.radius = naiveRadius;
        }

        return result;
    }

    static fromVertices(positions, center, stride, result) {
        if (!defined(result)) {
          result = new BoundingSphere();
        }
  
        if (!defined(positions) || positions.length === 0) {
            result.center.copy(Vector3.ZERO);
            result.radius = 0.0;
            return result;
        }
  
        center =defaultValue(center, Vector3.ZERO);
  
        stride = defaultValue(stride, 3);
  
        const currentPos = new Vector3();
        currentPos.x = positions[0] + center.x;
        currentPos.y = positions[1] + center.y;
        currentPos.z = positions[2] + center.z;
        
        const xMin = currentPos.clone();
        const yMin = currentPos.clone();
        const zMin = currentPos.clone();

        const xMax = currentPos.clone();
        const yMax = currentPos.clone();
        const zMax = currentPos.clone();

  
        const numElements = positions.length;
        let i;
        for (i = 0; i < numElements; i += stride) {
            const x = positions[i] + center.x;
            const y = positions[i + 1] + center.y;
            const z = positions[i + 2] + center.z;
    
            currentPos.x = x;
            currentPos.y = y;
            currentPos.z = z;
    
            // Store points containing the the smallest and largest components
            if (x < xMin.x) {
                xMin.copy(currentPos);
            }

            if (x > xMax.x) {
                xMin.copy(currentPos);
            }

            if (y < yMin.y) {
                yMin.copy(currentPos);
            }

            if (y > yMax.y) {
                yMax.copy(currentPos);
            }

            if (z < zMin.z) {
                zMin.copy(currentPos);
            }

            if (z > zMax.z) {
                zMax.copy(currentPos);
            }
        }
  
        // Compute x-, y-, and z-spans (Squared distances b/n each component's min. and max.).
        const xSpan = Vector3.subtract(xMax, xMin).lengthSquare();
        const ySpan = Vector3.subtract(yMax, yMin).lengthSquare();
        const zSpan = Vector3.subtract(zMax, zMin).lengthSquare();
  
        // Set the diameter endpoints to the largest span.
        let diameter1 = xMin;
        let diameter2 = xMax;
        let maxSpan = xSpan;
        if (ySpan > maxSpan) {
          maxSpan = ySpan;
          diameter1 = yMin;
          diameter2 = yMax;
        }
        if (zSpan > maxSpan) {
          maxSpan = zSpan;
          diameter1 = zMin;
          diameter2 = zMax;
        }
  
        // Calculate the center of the initial sphere found by Ritter's algorithm
        const ritterCenter = new Vector3();
        ritterCenter.x = (diameter1.x + diameter2.x) * 0.5;
        ritterCenter.y = (diameter1.y + diameter2.y) * 0.5;
        ritterCenter.z = (diameter1.z + diameter2.z) * 0.5;
  
        // Calculate the radius of the initial sphere found by Ritter's algorithm
        let radiusSquared = Vector3.subtract(diameter2, ritterCenter).lengthSquare();
        let ritterRadius = Math.sqrt(radiusSquared);

  
        // Find the center of the sphere found using the Naive method.
        const minBoxPt = new Vector3();
        minBoxPt.x = xMin.x;
        minBoxPt.y = yMin.y;
        minBoxPt.z = zMin.z;
  
        const maxBoxPt = new Vector3();
        maxBoxPt.x = xMax.x;
        maxBoxPt.y = yMax.y;
        maxBoxPt.z = zMax.z;
  
        const naiveCenter = Vector3.midpoint(minBoxPt, maxBoxPt);
  
        // Begin 2nd pass to find naive radius and modify the ritter sphere.
        let naiveRadius = 0;
        for (i = 0; i < numElements; i += stride) {
          currentPos.x = positions[i] + center.x;
          currentPos.y = positions[i + 1] + center.y;
          currentPos.z = positions[i + 2] + center.z;
  
          // Find the furthest point from the naive center to calculate the naive radius.
          const r = Vector3.subtract(currentPos, naiveCenter).length();
          if (r > naiveRadius) {
            naiveRadius = r;
          }
  
          // Make adjustments to the Ritter Sphere to include all points.
          const oldCenterToPointSquared = Vector3.subtract(currentPos, ritterCenter).lengthSquare();
          if (oldCenterToPointSquared > radiusSquared) {
            const oldCenterToPoint = Math.sqrt(oldCenterToPointSquared);
            // Calculate new radius to include the point that lies outside
            ritterRadius = (ritterRadius + oldCenterToPoint) * 0.5;
            radiusSquared = ritterRadius * ritterRadius;
            // Calculate center of new Ritter sphere
            const oldToNew = oldCenterToPoint - ritterRadius;
            ritterCenter.x =
              (ritterRadius * ritterCenter.x + oldToNew * currentPos.x) /
              oldCenterToPoint;
            ritterCenter.y =
              (ritterRadius * ritterCenter.y + oldToNew * currentPos.y) /
              oldCenterToPoint;
            ritterCenter.z =
              (ritterRadius * ritterCenter.z + oldToNew * currentPos.z) /
              oldCenterToPoint;
          }
        }
  
        if (ritterRadius < naiveRadius) {
            result.center = ritterCenter.clone();
          result.radius = ritterRadius;
        } else {
            result.center = naiveCenter.clone();
          result.radius = naiveRadius;
        }
  
        return result;
      }
}

class Plane {
    constructor(normal, distance) {
        this.normal = normal.clone();
        this.distance = distance;
    }

    static fromPointNormal(point, normal, result) {
        const distance = -Vector3.dot(normal, point);
        if (!defined(result)) result = new Plane(normal, distance);

        result.normal = normal.clone();
        result.distance = distance;
        return result;
    }

    static getPointDistance(plane, point) {
        return Vector3.dot(plane.normal, point) + plane.distance;
    }
}

class IntersectionTests {
    constructor(){}

    static rayPlane(ray, plane, result) {
        if (!defined(result)) result = new Vector3();
        const origin = ray.origin;
        const direction = ray.direction;
        const normal = plane.normal;
        const denominator = Vector3.dot(normal, direction);
        if (Math.abs(denominator) < EPSILON15) {
        // Ray is parallel to plane.  The ray may be in the polygon's plane.
            return undefined;
        }

        const t = (-plane.distance - Vector3.dot(normal, origin)) / denominator;

        if (t < 0) {
            return undefined;
        }

        Vector3.multiplyByScalar(direction, t, result);
        return result.add(origin);
    }
}

class Ray {
    constructor(origin, direction) {
        this.origin = origin || new Vector3();
        this.direction = direction || new Vector3();
    }
}

class EllipsoidTangentPlane {
    constructor(origin, ellipsoid) {
        ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
        origin = ellipsoid.scaleToGeodeticSurface(origin);

        const eastNorthUp = Transforms.eastNorthUpToFixedFrame(origin, ellipsoid);
        this.ellipsoid = ellipsoid;
        this.origin = origin;
        this.xAxis = Vector3.fromCartesian4(Matrix4.getColumn(eastNorthUp, 0));
        this.yAxis = Vector3.fromCartesian4(Matrix4.getColumn(eastNorthUp, 1));
        const normal = Vector3.fromCartesian4(Matrix4.getColumn(eastNorthUp, 2));
        this.plane = Plane.fromPointNormal(origin, normal);
    }

    projectPointToNearestOnPlane(cartesian, result) {
        if (!defined(result)) result = new Vector2();
        const ray = new Ray();
        ray.origin.copy(cartesian);
        ray.direction.copy(this.plane.normal);

        let intersectionPoint = IntersectionTests.rayPlane(ray, this.plane);
        if (!defined(intersectionPoint)) {
            ray.direction.negate();
            intersectionPoint = IntersectionTests.rayPlane(ray, this.plane);
        }

        const v = Vector3.subtract(intersectionPoint, this.origin, intersectionPoint);

        const x = Vector3.dot(this.xAxis, v);
        const y = Vector3.dot(this.yAxis, v);

        result.x = x;
        result.y = y;
        return result;
    }
}

class OrientedBoundingBox {
    constructor (center, halfAxes) {

        this.center = defaultValue(center, Vector3.ZERO).clone();
        this.halfAxes = defaultValue(halfAxes, Matrix3.ZERO).clone();
    }

    static fromRectangle(rectangle, minimumHeight, maximumHeight, ellipsoid, result) {
        if (!defined(result)) result = new OrientedBoundingBox();

        minimumHeight = defaultValue(minimumHeight, 0.0);
        maximumHeight = defaultValue(maximumHeight, 0.0);
        ellipsoid = defaultValue(ellipsoid, Ellipsoid.WGS84);
      
        let minX, maxX, minY, maxY, minZ, maxZ, plane;
      
        if (rectangle.width <= Math.PI) {
          // The bounding box will be aligned with the tangent plane at the center of the rectangle.
          const tangentPointCartographic = BoundingSphere.center(rectangle);
          const tangentPoint = ellipsoid.cartographicToCartesian(tangentPointCartographic);
          const tangentPlane = new EllipsoidTangentPlane(tangentPoint, ellipsoid);
          plane = tangentPlane.plane;
      
          // If the rectangle spans the equator, CW is instead aligned with the equator (because it sticks out the farthest at the equator).
          const lonCenter = tangentPointCartographic.longitude;
          const latCenter =
            rectangle.south < 0.0 && rectangle.north > 0.0
              ? 0.0
              : tangentPointCartographic.latitude;
      
          // Compute XY extents using the rectangle at maximum height
          const perimeterCartographicNC = Cartographic.fromRadians(
            lonCenter,
            rectangle.north,
            maximumHeight,
          );
          const perimeterCartographicNW = Cartographic.fromRadians(
            rectangle.west,
            rectangle.north,
            maximumHeight,
          );
          const perimeterCartographicCW = Cartographic.fromRadians(
            rectangle.west,
            latCenter,
            maximumHeight,
          );
          const perimeterCartographicSW = Cartographic.fromRadians(
            rectangle.west,
            rectangle.south,
            maximumHeight,
          );
          const perimeterCartographicSC = Cartographic.fromRadians(
            lonCenter,
            rectangle.south,
            maximumHeight,
          );
      
          const perimeterCartesianNC = ellipsoid.cartographicToCartesian(
            perimeterCartographicNC
          );
          let perimeterCartesianNW = ellipsoid.cartographicToCartesian(
            perimeterCartographicNW
          );
          const perimeterCartesianCW = ellipsoid.cartographicToCartesian(
            perimeterCartographicCW
          );
          let perimeterCartesianSW = ellipsoid.cartographicToCartesian(
            perimeterCartographicSW
          );
          const perimeterCartesianSC = ellipsoid.cartographicToCartesian(
            perimeterCartographicSC
          );
      
          const perimeterProjectedNC = tangentPlane.projectPointToNearestOnPlane(
            perimeterCartesianNC
          );
          const perimeterProjectedNW = tangentPlane.projectPointToNearestOnPlane(
            perimeterCartesianNW
          );
          const perimeterProjectedCW = tangentPlane.projectPointToNearestOnPlane(
            perimeterCartesianCW
          );
          const perimeterProjectedSW = tangentPlane.projectPointToNearestOnPlane(
            perimeterCartesianSW
          );
          const perimeterProjectedSC = tangentPlane.projectPointToNearestOnPlane(
            perimeterCartesianSC
          );
      
          minX = Math.min(
            perimeterProjectedNW.x,
            perimeterProjectedCW.x,
            perimeterProjectedSW.x
          );
          maxX = -minX; // symmetrical
      
          maxY = Math.max(perimeterProjectedNW.y, perimeterProjectedNC.y);
          minY = Math.min(perimeterProjectedSW.y, perimeterProjectedSC.y);
      
          // Compute minimum Z using the rectangle at minimum height, since it will be deeper than the maximum height
          perimeterCartographicNW.height = perimeterCartographicSW.height = minimumHeight;
          perimeterCartesianNW = ellipsoid.cartographicToCartesian(
            perimeterCartographicNW
          );
          perimeterCartesianSW = ellipsoid.cartographicToCartesian(
            perimeterCartographicSW
          );
      
          minZ = Math.min(
            Plane.getPointDistance(plane, perimeterCartesianNW),
            Plane.getPointDistance(plane, perimeterCartesianSW)
          );
          maxZ = maximumHeight; // Since the tangent plane touches the surface at height = 0, this is okay
      
          return OrientedBoundingBox.fromPlaneExtents(
            tangentPlane.origin,
            tangentPlane.xAxis,
            tangentPlane.yAxis,
            tangentPlane.zAxis,
            minX,
            maxX,
            minY,
            maxY,
            minZ,
            maxZ,
            result
          );
        }
    }

    static fromPlaneExtents(
        planeOrigin,
        planeXAxis,
        planeYAxis,
        planeZAxis,
        minimumX,
        maximumX,
        minimumY,
        maximumY,
        minimumZ,
        maximumZ,
        result
    ) {
        if (
            !defined(minimumX) ||
            !defined(maximumX) ||
            !defined(minimumY) ||
            !defined(maximumY) ||
            !defined(minimumZ) ||
            !defined(maximumZ)
        ) {
            throw new Error(
                "all extents (minimum/maximum X/Y/Z) are required."
            );
        }

        if (!defined(result)) result = new OrientedBoundingBox();
        const halfAxes = result.halfAxes;
        Matrix3.setColumn(halfAxes, 0, planeXAxis, halfAxes);
        Matrix3.setColumn(halfAxes, 1, planeYAxis, halfAxes);
        Matrix3.setColumn(halfAxes, 2, planeZAxis, halfAxes);
      
        let centerOffset = scratchOffset;
        centerOffset.x = (minimumX + maximumX) / 2.0;
        centerOffset.y = (minimumY + maximumY) / 2.0;
        centerOffset.z = (minimumZ + maximumZ) / 2.0;
      
        const scale = scratchScale117;
        scale.x = (maximumX - minimumX) / 2.0;
        scale.y = (maximumY - minimumY) / 2.0;
        scale.z = (maximumZ - minimumZ) / 2.0;
      
        const center = result.center;
        centerOffset = Matrix3.multiplyByVector(halfAxes, centerOffset, centerOffset);
        Vector3.add(planeOrigin, centerOffset, center);
        Matrix3.multiplyByScale(halfAxes, scale, halfAxes);

        return result;

    }
}

class Cartographic {
    constructor(longitude, latitude, height) {
        this.longitude = longitude || 0;
        this.latitude = latitude || 0;
        this.height = height || 0;
    }

    

    static fromRadians(longitude, latitude, height, result) {
        height = defaultValue(height, 0.0);
        if (!defined(result)) {
            return new Cartographic(longitude, latitude, height);
        }

        result.longitude = longitude;
        result.latitude = latitude;
        result.height = height;
        return result;
    }
}

class Ellipsoid {
    constructor(x, y, z) {
        x = x || 0;
        y = y || 0;
        z = z || 0;

        this.x = x;
        this.y = y;
        this.z = z;

        this.radii = new Vector3(x, y, z);
        this.radiiSquared = new Vector3(x * x, y * y, z * z);
        this.radiiToTheFourth = new Vector3(
            x * x * x * x,
            y * y * y * y,
            z * z * z * z
        );
        this.oneOverRadii = new Vector3(
            x === 0.0 ? 0.0 : 1.0 / x,
            y === 0.0 ? 0.0 : 1.0 / y,
            z === 0.0 ? 0.0 : 1.0 / z
        );

        this.oneOverRadiiSquared = new Vector3(
            x === 0.0 ? 0.0 : 1.0 / (x * x),
            y === 0.0 ? 0.0 : 1.0 / (y * y),
            z === 0.0 ? 0.0 : 1.0 / (z * z)
        );
        
        this.minimumRadius = Math.min(x, y, z);
        this.maximumRadius = Math.max(x, y, z);
        this.centerToleranceSquared = 0.1;
        this.squaredFirstEccentricity = 1 - (z * z) / (x * x);

        if (this.radiiSquared.z !== 0) {
            this.squaredXOverSquaredZ = this.radiiSquared.x / this.radiiSquared.z;
        }

    }

    static clone(source) {
        return new Ellipsoid(source.x, source.y, source.z);
    }

    transformPositionToScaledSpace(position, result) {
        if (!defined(result)) {
            result = new Vector3();
        }

        return Vector3.multiplyComponents(position, this.oneOverRadii, result);
    }

    geodeticSurfaceNormal(cartesian, result) {
        if (Vector3.equalsEpsilon(cartesian, Vector3.ZERO, EPSILON14)) {
            return undefined;
        }

        if (!defined(result)) result = new Vector3();

        let temp = this.oneOverRadiiSquared.clone();
        result = Vector3.multiplyComponents(cartesian, temp, result);
        return result.normalize();
    }
    cartographicToCartesian(cartographic, result) {
        
        if (!defined(result)) result = new Vector3();
        
        const cartographicToCartesianNormal = new Vector3();
        const cartographicToCartesianK = new Vector3();

        this.geodeticSurfaceNormalCartographic(cartographic, cartographicToCartesianNormal);
        
        Vector3.multiplyComponents(this.radiiSquared, cartographicToCartesianNormal, cartographicToCartesianK);
        const gamma = Math.sqrt(Vector3.dot(cartographicToCartesianNormal, cartographicToCartesianK));
        Vector3.divideByScalar(cartographicToCartesianK, gamma, cartographicToCartesianK);
        Vector3.multiplyByScalar(cartographicToCartesianNormal, cartographic.height, cartographicToCartesianNormal);

        return Vector3.add(cartographicToCartesianK, cartographicToCartesianNormal, result);
        
    }

    geodeticSurfaceNormalCartographic(cartographic, result) {
        if (!defined(result)) result = new Vector3();
        const longitude = cartographic.longitude;
        const latitude = cartographic.latitude;
        const cosLatitude = Math.cos(latitude);

        const x = cosLatitude * Math.cos(longitude);
        const y = cosLatitude * Math.sin(longitude);
        const z = Math.sin(latitude);
        
        result.set(x, y, z);
        return result.normalize();
    }

    scaleToGeodeticSurface(cartesian, result) {
        return scaleToGeodeticSurface(
            cartesian,
            this.oneOverRadii,
            this.oneOverRadiiSquared,
            this.centerToleranceSquared,
            result
          );
    }

}

Ellipsoid.WGS84 = Object.freeze(new Ellipsoid(6378137.0, 6378137.0, 6356752.3142451793));

class EllipsoidalOccluder {
    constructor(ellipsoid) {
        this.ellipsoid = ellipsoid;
        this.cameraPosition = new Vector3();
        this.cameraPositionInScaledSpace = new Vector3();
        this.distanceToLimbInScaledSquared = 0.0;
    }
    computeHorizonCullingPointPossiblyUnderEllipsoid(directionToPoint, positions, minimumHeight, result) {
        const possiblyShrunkEllipsoid = EllipsoidalOccluder.getPossiblyShrunkEllipsoid(
            this.ellipsoid,
            minimumHeight
        );
        return computeHorizonCullingPointFromPositions(
            possiblyShrunkEllipsoid,
            directionToPoint,
            positions,
            result
        );
    }

    static getPossiblyShrunkEllipsoid(ellipsoid, minimumHeight) {
        if (defined(minimumHeight) &&
            minimumHeight < 0.0 &&
            ellipsoid.minimumRadius > - minimumHeight
        ) {
            const ellipsoidShrunkRadii = new Vector3(
                ellipsoid.radii.x + minimumHeight,
                ellipsoid.radii.y + minimumHeight,
                ellipsoid.radii.z + minimumHeight,
            );
            ellipsoid = new Ellipsoid(
                ellipsoidShrunkRadii.x,
                ellipsoidShrunkRadii.y,
                ellipsoidShrunkRadii.z
            );
        }
        return ellipsoid;
    }

    static computeHorizonCullingPointFromPositions(ellipsoid, directionToPoint, positions, result) {
        if (!defined(result)) result = new Vector3();
        const scaledSpaceDirectionToPoint = EllipsoidalOccluder.computeScaledSpaceDirectionToPoint(ellipsoid, directionToPoint);

        let resultMagnitude = 0.0;
        for (let i = 0, len = positions.length; i < len; ++i) {
            const position = positions[i];
            const candidateMagnitude = EllipsoidalOccluder.computeMagnitude(
              ellipsoid,
              position,
              scaledSpaceDirectionToPoint
            );
            if (candidateMagnitude < 0.0) {
              // all points should face the same direction, but this one doesn't, so return undefined
              return undefined;
            }
            resultMagnitude = Math.max(resultMagnitude, candidateMagnitude);
          }
      
          return EllipsoidalOccluder.magnitudeToPoint(scaledSpaceDirectionToPoint, resultMagnitude, result);
    }

    static computeScaledSpaceDirectionToPoint(ellipsoid, directionToPoint){
        if (Vector3.equals(directionToPoint, Vector3.ZERO)) {
            return directionToPoint;
        }

        const directionToPointScratch = ellipsoid.transformPositionToScaledSpace(
            directionToPoint
        );

        return directionToPointScratch.normalize();
    }

    static computeMagnitude(ellipsoid, position, scaledSpaceDirectionToPoint) {
        const scaledSpacePosition = ellipsoid.transformPositionToScaledSpace(
            position
        );
        let magnitudeSquared = scaledSpacePosition.lengthSquare();
        let magnitude = scaledSpacePosition.length();
        const direction = Vector3.divideByScalar(scaledSpacePosition, magnitude);

        magnitudeSquared = Math.max(1.0, magnitudeSquared);
        magnitude = Math.max(1.0, magnitude);

        const cosAlpha = Vector3.dot(direction, scaledSpaceDirectionToPoint);
        const sinAlpha = Vector3.cross(direction, scaledSpaceDirectionToPoint, direction).length()
        
        const cosBeta = 1.0 / magnitude;
        const sinBeta = Math.sqrt(magnitudeSquared - 1.0) * cosBeta;

        return 1.0 / (cosAlpha * cosBeta - sinAlpha * sinBeta);
    }

    static magnitudeToPoint(scaledSpaceDirectionToPoint, resultMagnitude, result) {
        if (resultMagnitude <= 0.0 ||
            resultMagnitude === 1.0 / 0.0 ||
            resultMagnitude !== resultMagnitude) {
            return undefined; 
        }

        return Vector3.multiplyByScalar(scaledSpaceDirectionToPoint, resultMagnitude, result);
    }

    computeHorizonCullingPointFromVerticesPossiblyUnderEllipsoid(
        directionToPoint,
        vertices,
        stride,
        center,
        minimumHeight,
        result
    ) {
        const possiblyShrunkEllipsoid = EllipsoidalOccluder.getPossiblyShrunkEllipsoid(
            this.ellipsoid,
            minimumHeight
        );
        
        return EllipsoidalOccluder.computeHorizonCullingPointFromVertices(
            possiblyShrunkEllipsoid,
            directionToPoint,
            vertices,
            stride,
            center,
            result
        )

    }

    static computeHorizonCullingPointFromVertices(
        ellipsoid,
        directionToPoint,
        vertices,
        stride,
        center,
        result
    ) {
        if (!defined(result)) result = new Vector3();
        stride = defaultValue(stride, 3);
        center = defaultValue(center, Vector3.ZERO.clone());
        const scaledSpaceDirectionToPoint = EllipsoidalOccluder.computeScaledSpaceDirectionToPoint(
            ellipsoid,
            directionToPoint
          );
          let resultMagnitude = 0.0;
          const positionScratch = new Vector3();
          for (let i = 0, len = vertices.length; i < len; i += stride) {
            positionScratch.x = vertices[i] + center.x;
            positionScratch.y = vertices[i + 1] + center.y;
            positionScratch.z = vertices[i + 2] + center.z;
      
            const candidateMagnitude = EllipsoidalOccluder.computeMagnitude(
              ellipsoid,
              positionScratch,
              scaledSpaceDirectionToPoint
            );
            if (candidateMagnitude < 0.0) {
              // all points should face the same direction, but this one doesn't, so return undefined
              return undefined;
            }
            resultMagnitude = Math.max(resultMagnitude, candidateMagnitude);
          }
      
          return EllipsoidalOccluder.magnitudeToPoint(scaledSpaceDirectionToPoint, resultMagnitude, result);
    }

}

class AxisAlignedBoundingBox {
    constructor(minimum, maximum, center) {
        this.minimum = defaultValue(minimum, Vector3.ZERO).clone();
        this.maximum = defaultValue(maximum, Vector3.ZERO).clone();
        if (!defined(center)) {
            center = new Vector3(
                (this.minimum.x + this.maximum.x) * 0.5,
                (this.minimum.y + this.maximum.y) * 0.5,
                (this.minimum.z + this.maximum.z) * 0.5
            );
        } else {
            center = new Vector3(center.x, center.y, center.z);
        }
        this.center = center;
    }
}

class AttributeCompression {
    constructor(){}
    static compressTextureCoordinates(textureCoordinates) {
        const x = (textureCoordinates.x * 4095.0) | 0;
        const y = (textureCoordinates.y * 4095.0) | 0;
        return 4096 * x + y;
    }

    static octPackFloat(encoded) {
        return 256.0 * encoded.x + encoded.y;
    }

    static octDecode(x, y, result) {
        return AttributeCompression.octDecodeInRange(x, y, 255, result);
    }

    static decompressTextureCoordinates(compressed, result) {
        const temp = compressed / 4096.0;
        const xZeroTo4095 = Math.floor(temp);
        result.x = xZeroTo4095 / 4095.0;
        result.y = (compressed - xZeroTo4095 * 4096) / 4095;
        return result;
    }

    static octDecodeInRange(x, y, rangeMax, result) {
        if (x < 0 || x > rangeMax || y < 0 || y > rangeMax) {
            throw new Erro(
                `x and y must be unsigned normalized integers between 0 and ${rangeMax}`
            );
        }
        if (!defined(result)) result = new Vector3();
        result.x = fromSNorm(x, rangeMax);
        result.y = fromSNorm(y, rangeMax);
        result.z = 1.0 - (Math.abs(result.x) + Math.abs(result.y));
      
        if (result.z < 0.0) {
          const oldVX = result.x;
          result.x = (1.0 - Math.abs(result.y)) * signNotZero(oldVX);
          result.y = (1.0 - Math.abs(oldVX)) * signNotZero(result.y);
        }
      
        return result.normalize();
    }
}


const cartesian2Scratch = new Vector2();

class TerrainEncoding {
    constructor(
        center,
        axisAlignedBoundingBox,
        minimumHeight,
        maximumHeight,
        fromENU,
        hasVertexNormals,
        hasWebMercatorT,
        hasGeodeticSurfaceNormals,
        exaggeration,
        exaggerationRelativeHeight,
    ) {

        let quantization = TerrainQuantization.NONE;
        let toENU;
        let matrix;

        const cartesian3DimScratch = new Vector3();

        if (
           defined(axisAlignedBoundingBox) &&
           defined(minimumHeight) &&
           defined(maximumHeight) &&
           defined(fromENU)
        ) {
            const minimum = axisAlignedBoundingBox.minimum;
            const maximum = axisAlignedBoundingBox.maximum;

            const dimensions = Vector3.subtract(
                maximum,
                minimum,
                cartesian3DimScratch
            );
            const hDim = maximumHeight - minimumHeight;
            const maxDim = Math.max(Vector3.maximumComponent(dimensions), hDim);

            if (maxDim < SHIFT_LEFT_12 - 1.0) {
                quantization = TerrainQuantization.BITS12;
            } else {
                quantization = TerrainQuantization.NONE;
            }

            toENU = Matrix4.inverseTransformation(fromENU, new Matrix4());
            const matrix4Scratch13T = new Matrix4();
            const cartesian3Scratch13T = new Vector3();
            const matrix4Scratch2 = new Matrix4();

            const translation = Vector3.negate(minimum, cartesian3Scratch13T);
            
            Matrix4.multiply(
                Matrix4.fromTranslation(translation, matrix4Scratch13T),
                toENU,
                toENU
            );

            const scale = cartesian3Scratch13T;
            scale.x = 1.0 / dimensions.x;
            scale.y = 1.0 / dimensions.y;
            scale.z = 1.0 / dimensions.z;
            Matrix4.multiply(Matrix4.fromScale(scale, matrix4Scratch13T), toENU, toENU);

            matrix = Matrix4.clone(fromENU);
            Matrix4.setTranslation(matrix, Vector3.ZERO, matrix);

            fromENU = Matrix4.clone(fromENU, new Matrix4());


            const translationMatrix = Matrix4.fromTranslation(minimum, matrix4Scratch13T);

            const scaleMatrix = Matrix4.fromScale(dimensions, matrix4Scratch2);

            const st = Matrix4.multiply(translationMatrix, scaleMatrix, matrix4Scratch13T);

            Matrix4.multiply(fromENU, st, fromENU);

            Matrix4.multiply(matrix, st, matrix);
        }
        this.quantization = quantization;
        this.minimumHeight = minimumHeight;
        this.maximumHeight = maximumHeight;
        this.center = defined(center) ?  Vector3.clone(center) : new Vector3();
        this.toScaledENU = toENU;
        this.fromScaledENU = fromENU;

        this.matrix = matrix;
        this.hasVertexNormals = hasVertexNormals;
        this.hasWebMercatorT = defaultValue(hasWebMercatorT, false);
        this.hasGeodeticSurfaceNormals = defaultValue(
            hasGeodeticSurfaceNormals,
            false
        );
        this.exaggeration = defaultValue(exaggeration, 1.0);
        this.exaggerationRelativeHeight = defaultValue(
            exaggerationRelativeHeight,
            0.0
        );

        this.stride = 0;
        this._offsetGeodeticSurfaceNormal = 0;
        this._offsetVertexNormal = 0;
        this._calculateStrideAndOffsets();
    }
    _calculateStrideAndOffsets() {
        let vertexStride = 0;

        switch (this.quantization) {
            case TerrainQuantization.BITS12:
                vertexStride += 3;
                break;
            default:
                vertexStride += 6;
        }
        if (this.hasWebMercatorT) {
            vertexStride += 1;
        }
        if (this.hasVertexNormals) {
            this._offsetVertexNormal = vertexStride;
            vertexStride += 1;
        }
        if (this.hasGeodeticSurfaceNormals) {
            this._offsetGeodeticSurfaceNormal = vertexStride;
            vertexStride += 3;
        }

        this.stride = vertexStride;
    }
    encode(vertexBuffer, bufferIndex, position, uv, height, normalToPack, webMercatorT, geodeticSurfaceNormal) {
        const cartesian3Scratch13T = new Vector3();
        const cartesian2Scratch = new Vector2();
        const u = uv.x;
        const v = uv.y;
        if (this.quantization === TerrainQuantization.BITS12) {
            position = Matrix4.multiplyByPoint(
                this.toScaledENU,
                position,
                cartesian3Scratch13T
            );

            position.x = clamp(position.x, 0.0, 1.0);
            position.y = clamp(position.y, 0.0, 1.0);
            position.z = clamp(position.z, 0.0, 1.0);

            const hDim = this.maximumHeight - this.minimumHeight;
            const h = clamp((height - this.minimumHeight) / hDim, 0.0, 1.0);

            cartesian2Scratch.set(position.x, position.y);
            const compressed0 = AttributeCompression.compressTextureCoordinates(
                cartesian2Scratch
            );

            cartesian2Scratch.set(position.z, h);
            const compressed1 = AttributeCompression.compressTextureCoordinates(
                cartesian2Scratch
            );

            cartesian2Scratch.set(u, v);
            const compressed2 = AttributeCompression.compressTextureCoordinates(
                cartesian2Scratch
            );

            vertexBuffer[bufferIndex++] = compressed0;

            vertexBuffer[bufferIndex++] = compressed1;

            vertexBuffer[bufferIndex++] = compressed2;

            if (this.hasWebMercatorT) {
                cartesian2Scratch.set(webMercatorT, 0.0);
                const compressed3 = AttributeCompression.compressTextureCoordinates(
                    cartesian2Scratch
                );
                vertexBuffer[bufferIndex++] = compressed3;
            }
        } else {
            Vector3.subtract(position, this.center, cartesian3Scratch13T);
            vertexBuffer[bufferIndex++] = cartesian3Scratch13T.x;
            vertexBuffer[bufferIndex++] = cartesian3Scratch13T.y;
            vertexBuffer[bufferIndex++] = cartesian3Scratch13T.z;
            vertexBuffer[bufferIndex++] = height;
            vertexBuffer[bufferIndex++] = u;
            vertexBuffer[bufferIndex++] = v;
            
            if (this.hasWebMercatorT) {
                vertexBuffer[bufferIndex++] = webMercatorT;
            }
        }



        if (this.hasVertexNormals) {
            vertexBuffer[bufferIndex++] = AttributeCompression.octPackFloat(
                normalToPack
            );
        }

        if (this.hasGeodeticSurfaceNormals) {
            vertexBuffer[bufferIndex++] = geodeticSurfaceNormal.x;
            vertexBuffer[bufferIndex++] = geodeticSurfaceNormal.y;
            vertexBuffer[bufferIndex++] = geodeticSurfaceNormal.z;
        }

        return bufferIndex;
    }
    static clone(encoding, result) {
        if (!defined(encoding)) {
            return undefined;
        }
        if (!defined(result)) {
            result = new TerrainEncoding();
        }

        result.quantization = encoding.quantization;
        result.minimumHeight = encoding.minimumHeight;
        result.maximumHeight = encoding.maximumHeight;
        result.center = Vector3.clone(encoding.center);
        result.toScaledENU = Matrix4.clone(encoding.toScaledENU);
        result.fromScaledENU = Matrix4.clone(encoding.fromScaledENU);
        result.matrix = Matrix4.clone(encoding.matrix);
        result.hasVertexNormals = encoding.hasVertexNormals;
        result.hasWebMercatorT = encoding.hasWebMercatorT;
        result.hasGeodeticSurfaceNormals = encoding.hasGeodeticSurfaceNormals;
        result.exaggeration = encoding.exaggeration;
        result.exaggerationRelativeHeight = encoding.exaggerationRelativeHeight;

        result._calculateStrideAndOffsets();

        return result;
    }

    decodeTextureCoordinates(buffer, index, result) {
        if (!defined(result)) result = new Vector2();

        index *= this.stride;
        if (this.quantization === TerrainQuantization.BITS12) {
            return AttributeCompression.decompressTextureCoordinates(buffer[index + 2], result);
        }

        result.set(buffer[index + 4], buffer[index + 5]);
        return result;
    }

    decodeHeight(buffer, index) {
       
        index *= this.stride;
        if (this.quantization === TerrainQuantization.BITS12) {
            const zh = AttributeCompression.decompressTextureCoordinates(
                buffer[index + 1],
                cartesian2Scratch
            );
            return (
                zh.y * (this.maximumHeight - this.minimumHeight) + this.minimumHeight
            );
        }
        return buffer[index + 3];
    }

    getOctEncodedNormal(buffer, index, result) {
        if (!defined(result)) result = new Vector2();
        
        index = index * this.stride + this._offsetVertexNormal;
        const temp = buffer[index] / 256.0;
        const x = Math.floor(temp);
        const y = (temp - x) * 256.0;

        result.set(x, y);
        return result;
    }


}

class IndexDatatype {
    constructor() {}
    static createTypedArray(numberOfVertices, indicesLengthOrArray) {
        if (!defined(numberOfVertices)) {
            throw new Error("numberOfVertices is required");
        }

        if (numberOfVertices >= 6 * 1024 * 1024) {
            return new Uint32Array(indicesLengthOrArray);
        }

        return new Uint16Array(indicesLengthOrArray);
    }
}

class Vertex {
    constructor() {
      this.vertexBuffer = undefined;
      this.index = undefined;
      this.first = undefined;
      this.second = undefined;
      this.ratio = undefined;
    }

    clone(result) {
      if (!defined(result)) {
        result = new Vertex();
      }

      result.uBuffer = this.uBuffer;
      result.vBuffer = this.vBuffer;
      result.heightBuffer = this.heightBuffer;
      result.normalBuffer = this.normalBuffer;
      result.index = this.index;
      result.first = this.first;
      result.second = this.second;
      result.ratio = this.ratio;

      return result;
    }

    initializeIndexed(uBuffer, vBuffer, heightBuffer, normalBuffer, index) {
      this.uBuffer = uBuffer;
      this.vBuffer = vBuffer;
      this.heightBuffer = heightBuffer;
      this.normalBuffer = normalBuffer;
      this.index = index;
      this.first = undefined;
      this.second = undefined;
      this.ratio = undefined;
    }

    initializeFromClipResult(clipResult, index, vertices) {
      let nextIndex = index + 1;

      if (clipResult[index] !== -1) {
        vertices[clipResult[index]].clone(this);
      } else {
        this.vertexBuffer = undefined;
        this.index = undefined;
        this.first = vertices[clipResult[nextIndex]];
        ++nextIndex;
        this.second = vertices[clipResult[nextIndex]];
        ++nextIndex;
        this.ratio = clipResult[nextIndex];
        ++nextIndex;
      }

      return nextIndex;
    }

    getKey() {
      if (this.isIndexed()) {
        return this.index;
      }

      return JSON.stringify({
        first: this.first.getKey(),
        second: this.second.getKey(),
        ratio: this.ratio,
      });
    }

    isIndexed() {
      return defined(this.index);
    }

    getH() {
      if (this.isIndexed()) {
        return this.heightBuffer[this.index];
      }
      return lerp(this.first.getH(), this.second.getH(), this.ratio);
    }

    getU() {
      if (this.isIndexed()) {
        return this.uBuffer[this.index];
      }
      return lerp(this.first.getU(), this.second.getU(), this.ratio);
    }

    getV() {
      if (this.isIndexed()) {
        return this.vBuffer[this.index];
      }
      return lerp(this.first.getV(), this.second.getV(), this.ratio);
    }

    getNormalX() {
      if (this.isIndexed()) {
        return this.normalBuffer[this.index * 2];
      }

      encodedScratch = lerpOctEncodedNormal(this, encodedScratch);
      return encodedScratch.x;
    }

    getNormalY() {
      if (this.isIndexed()) {
        return this.normalBuffer[this.index * 2 + 1];
      }

      encodedScratch = lerpOctEncodedNormal(this, encodedScratch);
      return encodedScratch.y;
    }
}

const polygonVertices = [];
polygonVertices.push(new Vertex());
polygonVertices.push(new Vertex());
polygonVertices.push(new Vertex());
polygonVertices.push(new Vertex());

class Intersection {
    constructor(){}

    static clipTriangleAtAxisAlignedThreshold(threshold, keepAbove, u0, u1, u2, result) {
        if (!defined(result)) result = [];
        else result.length = 0;

        let u0Behind, u1Behind, u2Behind;
        if (keepAbove) {
        u0Behind = u0 < threshold;
        u1Behind = u1 < threshold;
        u2Behind = u2 < threshold;
        } else {
        u0Behind = u0 > threshold;
        u1Behind = u1 > threshold;
        u2Behind = u2 > threshold;
        }

        const numBehind = u0Behind + u1Behind + u2Behind;

        let u01Ratio, u02Ratio, u12Ratio, u10Ratio, u20Ratio, u21Ratio;
        if (numBehind === 1) {
        if (u0Behind) {
            u01Ratio = (threshold - u0) / (u1 - u0);
            u02Ratio = (threshold - u0) / (u2 - u0);
            result.push(1);
            result.push(2);

            if (u02Ratio !== 1.0) {
            result.push(-1);
            result.push(0);
            result.push(2);
            result.push(u02Ratio);
            }

            if (u01Ratio !== 1.0) {
            result.push(-1);
            result.push(0);
            result.push(1);
            result.push(u01Ratio);
            }
        }
        else if (u1Behind) {
            u12Ratio = (threshold - u1) / (u2 - u1);
            u10Ratio = (threshold - u1) / (u0 - u1);
            result.push(2);
            result.push(0);

            if (u10Ratio !== 1.0) {
            result.push(-1);
            result.push(1);
            result.push(0);
            result.push(u10Ratio);
            }

            if (u12Ratio !== 1.0) {
            result.push(-1);
            result.push(1);
            result.push(2);
            result.push(u12Ratio);
            }
        }
        else if (u2Behind) {
            u20Ratio = (threshold - u2) / (u0 - u2);
            u21Ratio = (threshold - u2) / (u1 - u2);
            result.push(0);
            result.push(1);

            if (u21Ratio !== 1.0) {
            result.push(-1);
            result.push(2);
            result.push(1);
            result.push(u21Ratio);
            }

            if (u20Ratio !== 1.0) {
            result.push(-1);
            result.push(2);
            result.push(0);
            result.push(u20Ratio);
            }
        }
        }
        else if (numBehind === 2) {
            if (!u0Behind && u0 !== threshold) {
                u10Ratio = (threshold - u1) / (u0 - u1);
                u20Ratio = (threshold - u2) / (u0 - u2);

                result.push(0);

                result.push(-1);
                result.push(1);
                result.push(0);
                result.push(u10Ratio);

                result.push(-1);
                result.push(2);
                result.push(0);
                result.push(u20Ratio);
            }
            else if (!u1Behind && u1 !== threshold) {
                u21Ratio = (threshold - u2) / (u1 - u2);
                u01Ratio = (threshold - u0) / (u1 - u0);

                result.push(1);

                result.push(-1);
                result.push(2);
                result.push(1);
                result.push(u21Ratio);

                result.push(-1);
                result.push(0);
                result.push(1);
                result.push(u01Ratio);
            }
            else if (!u2Behind && u2 !== threshold) {
                u02Ratio = (threshold - u0) / (u2 - u0);
                u12Ratio = (threshold - u1) / (u2 - u1);

                result.push(2);

                result.push(-1);
                result.push(0);
                result.push(2);
                result.push(u02Ratio);

                result.push(-1);
                result.push(1);
                result.push(2);
                result.push(u12Ratio);
            }
        }
        else if (numBehind !== 3) {
            result.push(0);
            result.push(1);
            result.push(2);
        }

        return result;
    }
}

const decodeTexCoordsScratch = new Vector2();
const octEncodedNormalScratch = new Vector3();
const uScratch = [];
const vScratch = [];
const heightScratch = [];
const indicesScratch = [];
const normalsScratch = [];

let cartographicScratch = new Cartographic();
let cartesian3Scratch = new Vector3();

let depth = -1;
const cartesianScratch1 = [new Vector3(), new Vector3()];
const cartesianScratch2 = [new Vector3(), new Vector3()];

let encodedScratch = new Vector2()


function upsampleQuantizedTerrainMesh(parameters) {

    const isEastChild = parameters.isEastChild;
    const isNorthChild = parameters.isNorthChild;

    const name = parameters.name;

    // UV坐标
    // U坐标 东边的瓦片是 [32767 / 2, 32767]，西边的是[0, 32767 / 2]
    // V坐标 北边的瓦片是 [32767 / 2, 32767]，南边的是[0, 32767 / 2]
    const minU = isEastChild ? halfMaxShort : 0;
    const maxU = isEastChild ? maxShort : halfMaxShort;
    const minV = isNorthChild ? halfMaxShort : 0;
    const maxV = isNorthChild ? maxShort : halfMaxShort;

    const uBuffer = uScratch;
    const vBuffer = vScratch;
    const heightBuffer = heightScratch;
    const normalBuffer = normalsScratch;

    uBuffer.length = vBuffer.length = heightBuffer.length = normalBuffer.length = 0;

    const indices = indicesScratch;
    indices.length = 0;

    const vertexMap = {};

    // 父节点的顶点和索引（不算裙边）
    const parentVertices = parameters.vertices;
    let parentIndices = parameters.indices;
    parentIndices = parentIndices.subarray(0, parameters.indexCountWithoutSkirts);
    const encoding = TerrainEncoding.clone(parameters.encoding);
    
    const hasVertexNormals = encoding.hasVertexNormals;
    
    let vertexCount = 0;
    const quantizedVerticeCount = parameters.vertexCountWithoutSkirts;
    
    const parentMinimumHeight = parameters.minimumHeight;
    const parentMaximumHeight = parameters.maximumHeight;

    const parentUBuffer = new Array(quantizedVerticeCount);
    const parentVBuffer = new Array(quantizedVerticeCount);
    const parentHeightBuffer = new Array(quantizedVerticeCount);
    const parentNormalBuffer = hasVertexNormals
      ? new Array(quantizedVerticeCount * 2)
      : undefined;

    const threshold = 20;
    let height;

    let i, n;
    let u, v;
    for (i = 0, n = 0; i < quantizedVerticeCount; ++i, n += 2) {
      const texCoords = encoding.decodeTextureCoordinates(parentVertices, i, decodeTexCoordsScratch);
      height = encoding.decodeHeight(parentVertices, i);

      u = clamp((texCoords.x * maxShort) | 0, 0, maxShort);
      v = clamp((texCoords.y * maxShort) | 0, 0, maxShort);
      parentHeightBuffer[i] = clamp((((height - parentMinimumHeight) / (parentMaximumHeight - parentMinimumHeight)) * maxShort) | 0, 0, maxShort);

      if (u < threshold) u = 0;
      if (v < threshold) v = 0;

      if (maxShort - u < threshold) u = maxShort;
      if (maxShort - v < threshold) v = maxShort;

      parentUBuffer[i] = u;
      parentVBuffer[i] = v;

      if (hasVertexNormals) {
        const encodedNormal = encoding.getOctEncodedNormal(parentVertices, i, octEncodedNormalScratch);
        parentNormalBuffer[n] = encodedNormal.x;
        parentNormalBuffer[n + 1] = encodedNormal.y;
      }

      if (
        ((isEastChild && u >= halfMaxShort) || (!isEastChild && u <= halfMaxShort)) &&
        ((isNorthChild && v >= halfMaxShort) || (!isNorthChild && v <= halfMaxShort))
      ) {
        vertexMap[i] = vertexCount;
        uBuffer.push(u);
        vBuffer.push(v);
        heightBuffer.push(parentHeightBuffer[i]);
        if (hasVertexNormals) {
          normalBuffer.push(parentNormalBuffer[n]);
          normalBuffer.push(parentNormalBuffer[n + 1]);
        }

        ++vertexCount;
      }

    }

    const triangleVertices = [];
    triangleVertices.push(new Vertex());
    triangleVertices.push(new Vertex());
    triangleVertices.push(new Vertex());

    const clippedTriangleVertices = [];
    clippedTriangleVertices.push(new Vertex());
    clippedTriangleVertices.push(new Vertex());
    clippedTriangleVertices.push(new Vertex());

    let clippedIndex;
    let clipped2;

    for (i = 0; i < parentIndices.length; i += 3) {
      const i0 = parentIndices[i];
      const i1 = parentIndices[i + 1];
      const i2 = parentIndices[i + 2];

      const u0 = parentUBuffer[i0];
      const u1 = parentUBuffer[i1];
      const u2 = parentUBuffer[i2];

      triangleVertices[0].initializeIndexed(parentUBuffer, parentVBuffer, parentHeightBuffer, parentNormalBuffer, i0);
      triangleVertices[1].initializeIndexed(parentUBuffer, parentVBuffer, parentHeightBuffer, parentNormalBuffer, i1);
      triangleVertices[2].initializeIndexed(parentUBuffer, parentVBuffer, parentHeightBuffer, parentNormalBuffer, i2);

      const clipped = Intersection.clipTriangleAtAxisAlignedThreshold(halfMaxShort, isEastChild, u0, u1, u2);
      
      clippedIndex = 0;

      if (clippedIndex >= clipped.length) continue;
      clippedIndex = clippedTriangleVertices[0].initializeFromClipResult(clipped, clippedIndex, triangleVertices);

      if (clippedIndex >= clipped.length) continue;
      clippedIndex = clippedTriangleVertices[1].initializeFromClipResult(clipped, clippedIndex, triangleVertices);

      if (clippedIndex >= clipped.length) continue;
      clippedIndex = clippedTriangleVertices[2].initializeFromClipResult(clipped, clippedIndex, triangleVertices);

      clipped2 = Intersection.clipTriangleAtAxisAlignedThreshold(halfMaxShort, isNorthChild, clippedTriangleVertices[0].getV(), clippedTriangleVertices[1].getV(), clippedTriangleVertices[2].getV());

      addClippedPolygon(uBuffer, vBuffer, heightBuffer, normalBuffer, indices, vertexMap, clipped2, clippedTriangleVertices, hasVertexNormals);

      if (clippedIndex < clipped.length) {
        clippedTriangleVertices[2].clone(clippedTriangleVertices[1]);
        clippedTriangleVertices[2].initializeFromClipResult(clipped, clippedIndex, triangleVertices);

        clipped2 = Intersection.clipTriangleAtAxisAlignedThreshold(halfMaxShort, isNorthChild, clippedTriangleVertices[0].getV(), clippedTriangleVertices[1].getV(), clippedTriangleVertices[2].getV());

        addClippedPolygon(uBuffer, vBuffer, heightBuffer, normalBuffer, indices, vertexMap, clipped2, clippedTriangleVertices, hasVertexNormals);
      }
    }

    const uOffset = isEastChild ? -maxShort : 0;
    const vOffset = isNorthChild ? -maxShort : 0;

    const westIndices = [], southIndices = [], eastIndices = [], northIndices = [];
    let minimumHeight = Number.MAX_VALUE, maximumHeight = -minimumHeight;

    const cartesianVertices = [];
    cartesianVertices.length = 0;

    const ellipsoid = Ellipsoid.clone(parameters.ellipsoid);
    const rectangle = Rectangle.clone(parameters.childRectangle);

    const north = rectangle.north, south = rectangle.south, west = rectangle.west;
    let east = rectangle.east;

    if (east < west) east += Math.PI * 2;

    for (i = 0; i < uBuffer.length; ++i) {
      u = Math.round(uBuffer[i]);
      if (u <= minU) {
        westIndices.push(i);
        u = 0;
      } else if (u >= maxU) {
        eastIndices.push(i);
        u = maxShort;
      } else {
        u = u * 2 + uOffset;
      }

      uBuffer[i] = u;

      v = Math.round(vBuffer[i]);
      if (v <= minV) {
        southIndices.push(i);
        v = 0;
      } else if (v >= maxV) {
        northIndices.push(i);
        v = maxShort;
      } else {
        v = v * 2 + vOffset;
      }

      vBuffer[i] = v;

      height = lerp(parentMinimumHeight, parentMaximumHeight, heightBuffer[i] / maxShort);
      if (height < minimumHeight) minimumHeight = height;
      if (height > maximumHeight) maximumHeight = height;

      heightBuffer[i] = height;

      cartographicScratch.longitude = lerp(west, east, u / maxShort);
      cartographicScratch.latitude = lerp(south, north, v / maxShort);
      cartographicScratch.height = height;

      ellipsoid.cartographicToCartesian(cartographicScratch, cartesian3Scratch);

      cartesianVertices.push(cartesian3Scratch.x);
      cartesianVertices.push(cartesian3Scratch.y);
      cartesianVertices.push(cartesian3Scratch.z);
    }

    

    const boundingSphere = BoundingSphere.fromVertices(cartesianVertices, Vector3.ZERO, 3);
    const orientedBoundingBox = OrientedBoundingBox.fromRectangle(rectangle, minimumHeight, maximumHeight, ellipsoid);

    const occluder = new  EllipsoidalOccluder(ellipsoid);
    const horizonOcclusionPoint = occluder.computeHorizonCullingPointFromVerticesPossiblyUnderEllipsoid(boundingSphere.center, cartesianVertices, 3, boundingSphere.center, minimumHeight);

    const heightRange = maximumHeight - minimumHeight;

    const vertices = new Uint16Array(uBuffer.length + vBuffer.length + heightBuffer.length);

    for (i = 0; i < uBuffer.length; ++i) {
      vertices[i] = uBuffer[i];
    }

    let start = uBuffer.length;

    for (i = 0; i < vBuffer.length; ++i) {
      vertices[start + i] = vBuffer[i];
    }

    start += vBuffer.length;

    for (i = 0; i < heightBuffer.length; ++i) {
      vertices[start + i] = (maxShort * (heightBuffer[i] - minimumHeight)) / heightRange;
    }

    const indicesTypedArray = IndexDatatype.createTypedArray(uBuffer.length, indices);

    let encodedNormals;
    if (hasVertexNormals) {
      const normalArray = new Uint8Array(normalBuffer);
      encodedNormals = normalArray.buffer;
    } 

    return {
      vertices: vertices.buffer,
      encodedNormals: encodedNormals,
      indices: indicesTypedArray.buffer,
      minimumHeight: minimumHeight,
      maximumHeight: maximumHeight,
      westIndices: westIndices,
      southIndices: southIndices,
      eastIndices: eastIndices,
      northIndices: northIndices,
      boundingSphere: boundingSphere,
      orientedBoundingBox: orientedBoundingBox,
      horizonOcclusionPoint: horizonOcclusionPoint,
      name: name,
      parameters: parameters
    }
}

function addClippedPolygon(uBuffer, vBuffer,heightBuffer, normalBuffer, indices, vertexMap, clipped, triangleVertices, hasVertexNormals) {
    if (clipped.length === 0) return;

    let numVertices = 0;
    let clippedIndex = 0;
    while (clippedIndex < clipped.length) {
      clippedIndex = polygonVertices[numVertices++].initializeFromClipResult(clipped, clippedIndex, triangleVertices);
    }
    
    for (let i = 0; i < numVertices; ++i) {
      const polygonVertex = polygonVertices[i];
      if (!polygonVertex.isIndexed()) {
        const key = polygonVertex.getKey();
        if (defined(vertexMap[key])) {
          polygonVertex.newIndex = vertexMap[key];
        } else {
          const newIndex = uBuffer.length;
          uBuffer.push(polygonVertex.getU());
          vBuffer.push(polygonVertex.getV());

          heightBuffer.push(polygonVertex.getH());
          if (hasVertexNormals) {
            normalBuffer.push(polygonVertex.getNormalX());
            normalBuffer.push(polygonVertex.getNormalY());
          }
          polygonVertex.newIndex = newIndex;
          vertexMap[key] = newIndex;
        }
      } else {
        polygonVertex.newIndex = vertexMap[polygonVertex.index];
        polygonVertex.uBuffer = uBuffer;
        polygonVertex.vBuffer = vBuffer;
        polygonVertex.heightBuffer = heightBuffer;
        if (hasVertexNormals) {
          polygonVertex.normalBuffer = normalBuffer;
        }
      }
    }

    if (numVertices === 3) {
      // 三个点，组成一个三角形
      indices.push(polygonVertices[0].newIndex);
      indices.push(polygonVertices[1].newIndex);
      indices.push(polygonVertices[2].newIndex);
    } else if (numVertices === 4) {
      // 四个点，组成两个三角形
      indices.push(polygonVertices[0].newIndex);
      indices.push(polygonVertices[1].newIndex);
      indices.push(polygonVertices[2].newIndex);

      indices.push(polygonVertices[0].newIndex);
      indices.push(polygonVertices[2].newIndex);
      indices.push(polygonVertices[3].newIndex);
    }
}

function lerpOctEncodedNormal(vertex, result) {
    ++depth;

    let first = cartesianScratch1[depth];
    let second = cartesianScratch2[depth];

    first = AttributeCompression.octDecode(vertex.first.getNormalX(), vertex.first.getNormalY(), first);
    second = AttributeCompression.octDecode(vertex.second.getNormalX(), vertex.second.getNormalY(), second);

    cartesian3Scratch = lerp(first, second, vertex.ratio);
    cartesian3Scratch.normalize();
    AttributeCompression.octDecode(cartesian3Scratch, result);

    --depth;
    return result;
}

onmessage = function(e) {
    const data = e.data;
    const id = data.id;
    const parameters = data.parameters;
    const responseData = {
        id: id,
        result: undefined,
        error: undefined
    }

    return Promise.resolve(
        upsampleQuantizedTerrainMesh(parameters)
    ).then(result => {
        responseData.result = result
    }).catch(e => {
        if (e instanceof Error) {
            responseData.error = {
                name: e.name,
                message: e.message,
                stack: e.stack
            }
        } else {
            responseData.error = e;
        }
    }).finally(() => {
        postMessage(responseData);
    })
}