341 lines
9.9 KiB
JavaScript
341 lines
9.9 KiB
JavaScript
goog.provide('ol.reproj.Triangulation');
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goog.require('goog.asserts');
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goog.require('goog.math');
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goog.require('ol.extent');
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goog.require('ol.proj');
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/**
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* Single triangle; consists of 3 source points and 3 target points.
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*
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* @typedef {{source: Array.<ol.Coordinate>,
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* target: Array.<ol.Coordinate>}}
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*/
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ol.reproj.Triangle;
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/**
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* @classdesc
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* Class containing triangulation of the given target extent.
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* Used for determining source data and the reprojection itself.
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*
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* @param {ol.proj.Projection} sourceProj Source projection.
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* @param {ol.proj.Projection} targetProj Target projection.
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* @param {ol.Extent} targetExtent Target extent to triangulate.
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* @param {ol.Extent} maxSourceExtent Maximal source extent that can be used.
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* @param {number} errorThreshold Acceptable error (in source units).
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* @constructor
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*/
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ol.reproj.Triangulation = function(sourceProj, targetProj, targetExtent,
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maxSourceExtent, errorThreshold) {
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/**
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* @type {ol.proj.Projection}
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* @private
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*/
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this.sourceProj_ = sourceProj;
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/**
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* @type {ol.proj.Projection}
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* @private
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*/
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this.targetProj_ = targetProj;
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/** @type {!Object.<string, ol.Coordinate>} */
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var transformInvCache = {};
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var transformInv = ol.proj.getTransform(this.targetProj_, this.sourceProj_);
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/**
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* @param {ol.Coordinate} c
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* @return {ol.Coordinate}
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* @private
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*/
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this.transformInv_ = function(c) {
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var key = c[0] + '/' + c[1];
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return transformInvCache[key] || (transformInvCache[key] = transformInv(c));
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};
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/**
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* @type {ol.Extent}
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* @private
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*/
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this.maxSourceExtent_ = maxSourceExtent;
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/**
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* @type {number}
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* @private
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*/
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this.errorThresholdSquared_ = errorThreshold * errorThreshold;
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/**
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* @type {Array.<ol.reproj.Triangle>}
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* @private
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*/
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this.triangles_ = [];
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/**
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* @type {ol.Extent}
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* @private
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*/
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this.trianglesSourceExtent_ = null;
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/**
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* Indicates that source coordinates have to be shifted during reprojection.
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* This is needed when the triangulation crosses
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* edge of the source projection (dateline).
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* @type {boolean}
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* @private
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*/
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this.wrapsXInSource_ = false;
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/**
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* @type {boolean}
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* @private
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*/
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this.canWrapXInSource_ = this.sourceProj_.canWrapX() &&
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!!maxSourceExtent &&
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!!this.sourceProj_.getExtent() &&
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(ol.extent.getWidth(maxSourceExtent) ==
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ol.extent.getWidth(this.sourceProj_.getExtent()));
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/**
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* @type {?number}
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* @private
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*/
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this.sourceWorldWidth_ = this.sourceProj_.getExtent() ?
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ol.extent.getWidth(this.sourceProj_.getExtent()) : null;
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/**
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* @type {?number}
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* @private
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*/
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this.targetWorldWidth_ = this.targetProj_.getExtent() ?
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ol.extent.getWidth(this.targetProj_.getExtent()) : null;
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var tlDst = ol.extent.getTopLeft(targetExtent);
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var trDst = ol.extent.getTopRight(targetExtent);
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var brDst = ol.extent.getBottomRight(targetExtent);
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var blDst = ol.extent.getBottomLeft(targetExtent);
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var tlDstSrc = this.transformInv_(tlDst);
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var trDstSrc = this.transformInv_(trDst);
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var brDstSrc = this.transformInv_(brDst);
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var blDstSrc = this.transformInv_(blDst);
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this.addQuad_(tlDst, trDst, brDst, blDst,
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tlDstSrc, trDstSrc, brDstSrc, blDstSrc,
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ol.RASTER_REPROJECTION_MAX_SUBDIVISION);
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transformInvCache = {};
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};
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/**
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* Adds triangle to the triangulation.
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* @param {ol.Coordinate} a
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* @param {ol.Coordinate} b
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* @param {ol.Coordinate} c
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* @param {ol.Coordinate} aSrc
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* @param {ol.Coordinate} bSrc
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* @param {ol.Coordinate} cSrc
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* @private
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*/
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ol.reproj.Triangulation.prototype.addTriangle_ = function(a, b, c,
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aSrc, bSrc, cSrc) {
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this.triangles_.push({
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source: [aSrc, bSrc, cSrc],
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target: [a, b, c]
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});
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};
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/**
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* Adds quad (points in clock-wise order) to the triangulation
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* (and reprojects the vertices) if valid.
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* Performs quad subdivision if needed to increase precision.
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*
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* @param {ol.Coordinate} a
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* @param {ol.Coordinate} b
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* @param {ol.Coordinate} c
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* @param {ol.Coordinate} d
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* @param {ol.Coordinate} aSrc
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* @param {ol.Coordinate} bSrc
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* @param {ol.Coordinate} cSrc
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* @param {ol.Coordinate} dSrc
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* @param {number} maxSubdiv Maximal allowed subdivision of the quad.
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* @private
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*/
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ol.reproj.Triangulation.prototype.addQuad_ = function(a, b, c, d,
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aSrc, bSrc, cSrc, dSrc, maxSubdiv) {
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var srcQuadExtent = ol.extent.boundingExtent([aSrc, bSrc, cSrc, dSrc]);
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var srcCoverageX = this.sourceWorldWidth_ ?
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ol.extent.getWidth(srcQuadExtent) / this.sourceWorldWidth_ : null;
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// when the quad is wrapped in the source projection
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// it covers most of the projection extent, but not fully
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var wrapsX = this.sourceProj_.canWrapX() &&
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srcCoverageX > 0.5 && srcCoverageX < 1;
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var needsSubdivision = false;
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if (maxSubdiv > 0) {
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if (this.targetProj_.isGlobal() && this.targetWorldWidth_) {
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var tgtQuadExtent = ol.extent.boundingExtent([a, b, c, d]);
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var tgtCoverageX =
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ol.extent.getWidth(tgtQuadExtent) / this.targetWorldWidth_;
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needsSubdivision |=
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tgtCoverageX > ol.RASTER_REPROJECTION_MAX_TRIANGLE_WIDTH;
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}
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if (!wrapsX && this.sourceProj_.isGlobal() && srcCoverageX) {
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needsSubdivision |=
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srcCoverageX > ol.RASTER_REPROJECTION_MAX_TRIANGLE_WIDTH;
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}
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}
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if (!needsSubdivision && this.maxSourceExtent_) {
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if (!ol.extent.intersects(srcQuadExtent, this.maxSourceExtent_)) {
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// whole quad outside source projection extent -> ignore
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return;
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}
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}
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if (!needsSubdivision) {
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if (!isFinite(aSrc[0]) || !isFinite(aSrc[1]) ||
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!isFinite(bSrc[0]) || !isFinite(bSrc[1]) ||
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!isFinite(cSrc[0]) || !isFinite(cSrc[1]) ||
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!isFinite(dSrc[0]) || !isFinite(dSrc[1])) {
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if (maxSubdiv > 0) {
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needsSubdivision = true;
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} else {
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return;
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}
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}
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}
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if (maxSubdiv > 0) {
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if (!needsSubdivision) {
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var center = [(a[0] + c[0]) / 2, (a[1] + c[1]) / 2];
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var centerSrc = this.transformInv_(center);
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var dx;
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if (wrapsX) {
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goog.asserts.assert(this.sourceWorldWidth_);
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var centerSrcEstimX =
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(goog.math.modulo(aSrc[0], this.sourceWorldWidth_) +
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goog.math.modulo(cSrc[0], this.sourceWorldWidth_)) / 2;
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dx = centerSrcEstimX -
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goog.math.modulo(centerSrc[0], this.sourceWorldWidth_);
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} else {
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dx = (aSrc[0] + cSrc[0]) / 2 - centerSrc[0];
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}
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var dy = (aSrc[1] + cSrc[1]) / 2 - centerSrc[1];
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var centerSrcErrorSquared = dx * dx + dy * dy;
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needsSubdivision = centerSrcErrorSquared > this.errorThresholdSquared_;
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}
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if (needsSubdivision) {
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if (Math.abs(a[0] - c[0]) <= Math.abs(a[1] - c[1])) {
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// split horizontally (top & bottom)
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var bc = [(b[0] + c[0]) / 2, (b[1] + c[1]) / 2];
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var bcSrc = this.transformInv_(bc);
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var da = [(d[0] + a[0]) / 2, (d[1] + a[1]) / 2];
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var daSrc = this.transformInv_(da);
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this.addQuad_(a, b, bc, da, aSrc, bSrc, bcSrc, daSrc, maxSubdiv - 1);
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this.addQuad_(da, bc, c, d, daSrc, bcSrc, cSrc, dSrc, maxSubdiv - 1);
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} else {
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// split vertically (left & right)
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var ab = [(a[0] + b[0]) / 2, (a[1] + b[1]) / 2];
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var abSrc = this.transformInv_(ab);
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var cd = [(c[0] + d[0]) / 2, (c[1] + d[1]) / 2];
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var cdSrc = this.transformInv_(cd);
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this.addQuad_(a, ab, cd, d, aSrc, abSrc, cdSrc, dSrc, maxSubdiv - 1);
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this.addQuad_(ab, b, c, cd, abSrc, bSrc, cSrc, cdSrc, maxSubdiv - 1);
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}
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return;
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}
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}
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if (wrapsX) {
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if (!this.canWrapXInSource_) {
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return;
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}
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this.wrapsXInSource_ = true;
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}
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this.addTriangle_(a, c, d, aSrc, cSrc, dSrc);
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this.addTriangle_(a, b, c, aSrc, bSrc, cSrc);
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};
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/**
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* Calculates extent of the 'source' coordinates from all the triangles.
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* The left bound of the returned extent can be higher than the right bound,
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* if the triangulation wraps X in source (see
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* {@link ol.reproj.Triangulation#getWrapsXInSource}).
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*
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* @return {ol.Extent} Calculated extent.
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*/
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ol.reproj.Triangulation.prototype.calculateSourceExtent = function() {
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if (this.trianglesSourceExtent_) {
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return this.trianglesSourceExtent_;
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}
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var extent = ol.extent.createEmpty();
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if (this.wrapsXInSource_) {
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// although only some of the triangles are crossing the dateline,
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// all coordinates need to be "shifted" to be positive
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// to properly calculate the extent (and then possibly shifted back)
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this.triangles_.forEach(function(triangle, i, arr) {
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goog.asserts.assert(this.sourceWorldWidth_);
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var src = triangle.source;
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ol.extent.extendCoordinate(extent,
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[goog.math.modulo(src[0][0], this.sourceWorldWidth_), src[0][1]]);
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ol.extent.extendCoordinate(extent,
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[goog.math.modulo(src[1][0], this.sourceWorldWidth_), src[1][1]]);
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ol.extent.extendCoordinate(extent,
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[goog.math.modulo(src[2][0], this.sourceWorldWidth_), src[2][1]]);
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}, this);
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var sourceProjExtent = this.sourceProj_.getExtent();
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var right = sourceProjExtent[2];
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if (extent[0] > right) {
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extent[0] -= this.sourceWorldWidth_;
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}
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if (extent[2] > right) {
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extent[2] -= this.sourceWorldWidth_;
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}
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} else {
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this.triangles_.forEach(function(triangle, i, arr) {
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var src = triangle.source;
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ol.extent.extendCoordinate(extent, src[0]);
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ol.extent.extendCoordinate(extent, src[1]);
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ol.extent.extendCoordinate(extent, src[2]);
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});
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}
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this.trianglesSourceExtent_ = extent;
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return extent;
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};
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/**
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* @return {boolean} Whether the source coordinates are wrapped in X
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* (the triangulation "crosses the dateline").
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*/
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ol.reproj.Triangulation.prototype.getWrapsXInSource = function() {
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return this.wrapsXInSource_;
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};
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/**
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* @return {Array.<ol.reproj.Triangle>} Array of the calculated triangles.
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*/
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ol.reproj.Triangulation.prototype.getTriangles = function() {
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return this.triangles_;
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};
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