cesiumDemo/Source/Scene/TileOrientedBoundingBox.js

import BoundingSphere from '../Core/BoundingSphere.js';
import BoxOutlineGeometry from '../Core/BoxOutlineGeometry.js';
import Cartesian3 from '../Core/Cartesian3.js';
import Check from '../Core/Check.js';
import ColorGeometryInstanceAttribute from '../Core/ColorGeometryInstanceAttribute.js';
import defineProperties from '../Core/defineProperties.js';
import GeometryInstance from '../Core/GeometryInstance.js';
import Matrix3 from '../Core/Matrix3.js';
import Matrix4 from '../Core/Matrix4.js';
import CesiumMath from '../Core/Math.js';
import OrientedBoundingBox from '../Core/OrientedBoundingBox.js';
import PerInstanceColorAppearance from './PerInstanceColorAppearance.js';
import Primitive from './Primitive.js';

    var scratchU = new Cartesian3();
    var scratchV = new Cartesian3();
    var scratchW = new Cartesian3();
    var scratchCartesian = new Cartesian3();

    function computeMissingVector(a, b, result) {
        result = Cartesian3.cross(a, b, result);
        var magnitude = Cartesian3.magnitude(result);
        return Cartesian3.multiplyByScalar(result, CesiumMath.EPSILON7 / magnitude, result);
    }

    function findOrthogonalVector(a, result) {
        var temp = Cartesian3.normalize(a, scratchCartesian);
        var b = Cartesian3.equalsEpsilon(temp, Cartesian3.UNIT_X, CesiumMath.EPSILON6) ? Cartesian3.UNIT_Y : Cartesian3.UNIT_X;
        return computeMissingVector(a, b, result);
    }

    function checkHalfAxes(halfAxes) {
        var u = Matrix3.getColumn(halfAxes, 0, scratchU);
        var v = Matrix3.getColumn(halfAxes, 1, scratchV);
        var w = Matrix3.getColumn(halfAxes, 2, scratchW);

        var uZero = Cartesian3.equals(u, Cartesian3.ZERO);
        var vZero = Cartesian3.equals(v, Cartesian3.ZERO);
        var wZero = Cartesian3.equals(w, Cartesian3.ZERO);

        if (!uZero && !vZero && !wZero) {
            return halfAxes;
        }
        if (uZero && vZero && wZero) {
            halfAxes[0] = CesiumMath.EPSILON7;
            halfAxes[4] = CesiumMath.EPSILON7;
            halfAxes[8] = CesiumMath.EPSILON7;
            return halfAxes;
        }
        if (uZero && !vZero && !wZero) {
            u = computeMissingVector(v, w, u);
        } else if (!uZero && vZero && !wZero) {
            v = computeMissingVector(u, w, v);
        } else if (!uZero && !vZero && wZero) {
            w = computeMissingVector(v, u, w);
        } else if (!uZero) {
            v = findOrthogonalVector(u, v);
            w = computeMissingVector(v, u, w);
        } else if (!vZero) {
            u = findOrthogonalVector(v, u);
            w = computeMissingVector(v, u, w);
        } else if (!wZero) {
            u = findOrthogonalVector(w, u);
            v = computeMissingVector(w, u, v);
        }

        Matrix3.setColumn(halfAxes, 0, u, halfAxes);
        Matrix3.setColumn(halfAxes, 1, v, halfAxes);
        Matrix3.setColumn(halfAxes, 2, w, halfAxes);

        return halfAxes;
    }

    /**
     * A tile bounding volume specified as an oriented bounding box.
     * @alias TileOrientedBoundingBox
     * @constructor
     *
     * @param {Cartesian3} [center=Cartesian3.ZERO] The center of the box.
     * @param {Matrix3} [halfAxes=Matrix3.ZERO] The three orthogonal half-axes of the bounding box.
     *                                          Equivalently, the transformation matrix, to rotate and scale a 2x2x2
     *                                          cube centered at the origin.
     *
     * @private
     */
    function TileOrientedBoundingBox(center, halfAxes) {
        halfAxes = checkHalfAxes(halfAxes);
        this._orientedBoundingBox = new OrientedBoundingBox(center, halfAxes);
        this._boundingSphere = BoundingSphere.fromOrientedBoundingBox(this._orientedBoundingBox);
    }

    defineProperties(TileOrientedBoundingBox.prototype, {
        /**
         * The underlying bounding volume.
         *
         * @memberof TileOrientedBoundingBox.prototype
         *
         * @type {Object}
         * @readonly
         */
        boundingVolume : {
            get : function() {
                return this._orientedBoundingBox;
            }
        },
        /**
         * The underlying bounding sphere.
         *
         * @memberof TileOrientedBoundingBox.prototype
         *
         * @type {BoundingSphere}
         * @readonly
         */
        boundingSphere : {
            get : function() {
                return this._boundingSphere;
            }
        }
    });

    /**
     * Computes the distance between this bounding box and the camera attached to frameState.
     *
     * @param {FrameState} frameState The frameState to which the camera is attached.
     * @returns {Number} The distance between the camera and the bounding box in meters. Returns 0 if the camera is inside the bounding volume.
     */
    TileOrientedBoundingBox.prototype.distanceToCamera = function(frameState) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined('frameState', frameState);
        //>>includeEnd('debug');
        return Math.sqrt(this._orientedBoundingBox.distanceSquaredTo(frameState.camera.positionWC));
    };

    /**
     * Determines which side of a plane this box is located.
     *
     * @param {Plane} plane The plane to test against.
     * @returns {Intersect} {@link Intersect.INSIDE} if the entire box is on the side of the plane
     *                      the normal is pointing, {@link Intersect.OUTSIDE} if the entire box is
     *                      on the opposite side, and {@link Intersect.INTERSECTING} if the box
     *                      intersects the plane.
     */
    TileOrientedBoundingBox.prototype.intersectPlane = function(plane) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined('plane', plane);
        //>>includeEnd('debug');
        return this._orientedBoundingBox.intersectPlane(plane);
    };

    /**
     * Update the bounding box after the tile is transformed.
     *
     * @param {Cartesian3} center The center of the box.
     * @param {Matrix3} halfAxes The three orthogonal half-axes of the bounding box.
     *                           Equivalently, the transformation matrix, to rotate and scale a 2x2x2
     *                           cube centered at the origin.
     */
    TileOrientedBoundingBox.prototype.update = function(center, halfAxes) {
        Cartesian3.clone(center, this._orientedBoundingBox.center);
        halfAxes = checkHalfAxes(halfAxes);
        Matrix3.clone(halfAxes, this._orientedBoundingBox.halfAxes);
        BoundingSphere.fromOrientedBoundingBox(this._orientedBoundingBox, this._boundingSphere);
    };

    /**
     * Creates a debug primitive that shows the outline of the box.
     *
     * @param {Color} color The desired color of the primitive's mesh
     * @return {Primitive}
     */
    TileOrientedBoundingBox.prototype.createDebugVolume = function(color) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined('color', color);
        //>>includeEnd('debug');

        var geometry = new BoxOutlineGeometry({
            // Make a 2x2x2 cube
            minimum : new Cartesian3(-1.0, -1.0, -1.0),
            maximum : new Cartesian3(1.0, 1.0, 1.0)
        });
        var modelMatrix = Matrix4.fromRotationTranslation(this.boundingVolume.halfAxes, this.boundingVolume.center);
        var instance = new GeometryInstance({
            geometry : geometry,
            id : 'outline',
            modelMatrix : modelMatrix,
            attributes : {
                color : ColorGeometryInstanceAttribute.fromColor(color)
            }
        });

        return new Primitive({
            geometryInstances : instance,
            appearance : new PerInstanceColorAppearance({
                translucent : false,
                flat : true
            }),
            asynchronous : false
        });
    };
export default TileOrientedBoundingBox;