cesium/Source/Core/CoplanarPolygonGeometryLibrary.js

CesiumJS is a JavaScript library for creating 3D globes and 2D maps in a web browser without a plugin.

import Cartesian2 from './Cartesian2.js';
import Cartesian3 from './Cartesian3.js';
import Check from './Check.js';
import Matrix3 from './Matrix3.js';
import OrientedBoundingBox from './OrientedBoundingBox.js';

    /**
     * @private
     */
    var CoplanarPolygonGeometryLibrary = {};

    var scratchIntersectionPoint = new Cartesian3();
    var scratchXAxis = new Cartesian3();
    var scratchYAxis = new Cartesian3();
    var scratchZAxis = new Cartesian3();
    var obbScratch = new OrientedBoundingBox();

    CoplanarPolygonGeometryLibrary.validOutline = function(positions) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined('positions', positions);
        //>>includeEnd('debug');

        var orientedBoundingBox = OrientedBoundingBox.fromPoints(positions, obbScratch);
        var halfAxes = orientedBoundingBox.halfAxes;
        var xAxis = Matrix3.getColumn(halfAxes, 0, scratchXAxis);
        var yAxis = Matrix3.getColumn(halfAxes, 1, scratchYAxis);
        var zAxis = Matrix3.getColumn(halfAxes, 2, scratchZAxis);

        var xMag = Cartesian3.magnitude(xAxis);
        var yMag = Cartesian3.magnitude(yAxis);
        var zMag = Cartesian3.magnitude(zAxis);

        // If all the points are on a line return undefined because we can't draw a polygon
        return !((xMag === 0 && (yMag === 0 || zMag === 0)) || (yMag === 0 && zMag === 0));
    };

    // call after removeDuplicates
    CoplanarPolygonGeometryLibrary.computeProjectTo2DArguments = function(positions, centerResult, planeAxis1Result, planeAxis2Result) {
        //>>includeStart('debug', pragmas.debug);
        Check.defined('positions', positions);
        Check.defined('centerResult', centerResult);
        Check.defined('planeAxis1Result', planeAxis1Result);
        Check.defined('planeAxis2Result', planeAxis2Result);
        //>>includeEnd('debug');

        var orientedBoundingBox = OrientedBoundingBox.fromPoints(positions, obbScratch);
        var halfAxes = orientedBoundingBox.halfAxes;
        var xAxis = Matrix3.getColumn(halfAxes, 0, scratchXAxis);
        var yAxis = Matrix3.getColumn(halfAxes, 1, scratchYAxis);
        var zAxis = Matrix3.getColumn(halfAxes, 2, scratchZAxis);

        var xMag = Cartesian3.magnitude(xAxis);
        var yMag = Cartesian3.magnitude(yAxis);
        var zMag = Cartesian3.magnitude(zAxis);
        var min = Math.min(xMag, yMag, zMag);

        // If all the points are on a line return undefined because we can't draw a polygon
        if ((xMag === 0 && (yMag === 0 || zMag === 0)) || (yMag === 0 && zMag === 0)) {
            return false;
        }

        var planeAxis1;
        var planeAxis2;

        if (min === yMag || min === zMag) {
            planeAxis1 = xAxis;
        }
        if (min === xMag) {
            planeAxis1 = yAxis;
        } else if (min === zMag) {
            planeAxis2 = yAxis;
        }
        if (min === xMag || min === yMag) {
            planeAxis2 = zAxis;
        }

        Cartesian3.normalize(planeAxis1, planeAxis1Result);
        Cartesian3.normalize(planeAxis2, planeAxis2Result);
        Cartesian3.clone(orientedBoundingBox.center, centerResult);
        return true;
    };

    function projectTo2D(position, center, axis1, axis2, result) {
        var v = Cartesian3.subtract(position, center, scratchIntersectionPoint);
        var x = Cartesian3.dot(axis1, v);
        var y = Cartesian3.dot(axis2, v);

        return Cartesian2.fromElements(x, y, result);
    }

    CoplanarPolygonGeometryLibrary.createProjectPointsTo2DFunction = function(center, axis1, axis2) {
        return function(positions) {
            var positionResults = new Array(positions.length);
            for (var i = 0; i < positions.length; i++) {
                positionResults[i] = projectTo2D(positions[i], center, axis1, axis2);
            }

            return positionResults;
        };
    };

    CoplanarPolygonGeometryLibrary.createProjectPointTo2DFunction = function(center, axis1, axis2) {
        return function(position, result) {
            return projectTo2D(position, center, axis1, axis2, result);
        };
    };
export default CoplanarPolygonGeometryLibrary;