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366 lines
16 KiB
JavaScript
366 lines
16 KiB
JavaScript
/**
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* @module ol/reproj/Triangulation
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*/
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import { boundingExtent, createEmpty, extendCoordinate, getArea, getBottomLeft, getBottomRight, getTopLeft, getTopRight, getWidth, intersects, } from '../extent.js';
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import { getTransform } from '../proj.js';
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import { log2, modulo } from '../math.js';
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/**
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* Single triangle; consists of 3 source points and 3 target points.
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* @typedef {Object} Triangle
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* @property {Array<import("../coordinate.js").Coordinate>} source Source.
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* @property {Array<import("../coordinate.js").Coordinate>} target Target.
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*/
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/**
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* Maximum number of subdivision steps during raster reprojection triangulation.
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* Prevents high memory usage and large number of proj4 calls (for certain
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* transformations and areas). At most `2*(2^this)` triangles are created for
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* each triangulated extent (tile/image).
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* @type {number}
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*/
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var MAX_SUBDIVISION = 10;
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/**
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* Maximum allowed size of triangle relative to world width. When transforming
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* corners of world extent between certain projections, the resulting
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* triangulation seems to have zero error and no subdivision is performed. If
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* the triangle width is more than this (relative to world width; 0-1),
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* subdivison is forced (up to `MAX_SUBDIVISION`). Default is `0.25`.
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* @type {number}
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*/
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var MAX_TRIANGLE_WIDTH = 0.25;
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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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var Triangulation = /** @class */ (function () {
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/**
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* @param {import("../proj/Projection.js").default} sourceProj Source projection.
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* @param {import("../proj/Projection.js").default} targetProj Target projection.
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* @param {import("../extent.js").Extent} targetExtent Target extent to triangulate.
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* @param {import("../extent.js").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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* @param {?number} opt_destinationResolution The (optional) resolution of the destination.
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*/
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function Triangulation(sourceProj, targetProj, targetExtent, maxSourceExtent, errorThreshold, opt_destinationResolution) {
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/**
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* @type {import("../proj/Projection.js").default}
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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 {import("../proj/Projection.js").default}
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* @private
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*/
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this.targetProj_ = targetProj;
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/** @type {!Object<string, import("../coordinate.js").Coordinate>} */
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var transformInvCache = {};
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var transformInv = getTransform(this.targetProj_, this.sourceProj_);
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/**
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* @param {import("../coordinate.js").Coordinate} c A coordinate.
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* @return {import("../coordinate.js").Coordinate} Transformed 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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if (!transformInvCache[key]) {
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transformInvCache[key] = transformInv(c);
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}
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return transformInvCache[key];
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};
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/**
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* @type {import("../extent.js").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<Triangle>}
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* @private
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*/
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this.triangles_ = [];
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/**
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* Indicates that the triangulation crosses edge of the source projection.
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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_ =
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this.sourceProj_.canWrapX() &&
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!!maxSourceExtent &&
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!!this.sourceProj_.getExtent() &&
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getWidth(maxSourceExtent) == 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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? getWidth(this.sourceProj_.getExtent())
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: 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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? getWidth(this.targetProj_.getExtent())
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: null;
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var destinationTopLeft = getTopLeft(targetExtent);
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var destinationTopRight = getTopRight(targetExtent);
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var destinationBottomRight = getBottomRight(targetExtent);
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var destinationBottomLeft = getBottomLeft(targetExtent);
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var sourceTopLeft = this.transformInv_(destinationTopLeft);
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var sourceTopRight = this.transformInv_(destinationTopRight);
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var sourceBottomRight = this.transformInv_(destinationBottomRight);
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var sourceBottomLeft = this.transformInv_(destinationBottomLeft);
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/*
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* The maxSubdivision controls how many splittings of the target area can
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* be done. The idea here is to do a linear mapping of the target areas
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* but the actual overal reprojection (can be) extremely non-linear. The
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* default value of MAX_SUBDIVISION was chosen based on mapping a 256x256
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* tile size. However this function is also called to remap canvas rendered
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* layers which can be much larger. This calculation increases the maxSubdivision
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* value by the right factor so that each 256x256 pixel area has
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* MAX_SUBDIVISION divisions.
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*/
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var maxSubdivision = MAX_SUBDIVISION +
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(opt_destinationResolution
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? Math.max(0, Math.ceil(log2(getArea(targetExtent) /
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(opt_destinationResolution *
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opt_destinationResolution *
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256 *
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256))))
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: 0);
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this.addQuad_(destinationTopLeft, destinationTopRight, destinationBottomRight, destinationBottomLeft, sourceTopLeft, sourceTopRight, sourceBottomRight, sourceBottomLeft, maxSubdivision);
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if (this.wrapsXInSource_) {
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var leftBound_1 = Infinity;
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this.triangles_.forEach(function (triangle, i, arr) {
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leftBound_1 = Math.min(leftBound_1, triangle.source[0][0], triangle.source[1][0], triangle.source[2][0]);
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});
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// Shift triangles to be as close to `leftBound` as possible
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// (if the distance is more than `worldWidth / 2` it can be closer.
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this.triangles_.forEach(function (triangle) {
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if (Math.max(triangle.source[0][0], triangle.source[1][0], triangle.source[2][0]) -
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leftBound_1 >
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this.sourceWorldWidth_ / 2) {
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var newTriangle = [
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[triangle.source[0][0], triangle.source[0][1]],
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[triangle.source[1][0], triangle.source[1][1]],
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[triangle.source[2][0], triangle.source[2][1]],
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];
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if (newTriangle[0][0] - leftBound_1 > this.sourceWorldWidth_ / 2) {
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newTriangle[0][0] -= this.sourceWorldWidth_;
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}
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if (newTriangle[1][0] - leftBound_1 > this.sourceWorldWidth_ / 2) {
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newTriangle[1][0] -= this.sourceWorldWidth_;
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}
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if (newTriangle[2][0] - leftBound_1 > this.sourceWorldWidth_ / 2) {
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newTriangle[2][0] -= this.sourceWorldWidth_;
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}
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// Rarely (if the extent contains both the dateline and prime meridian)
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// the shift can in turn break some triangles.
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// Detect this here and don't shift in such cases.
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var minX = Math.min(newTriangle[0][0], newTriangle[1][0], newTriangle[2][0]);
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var maxX = Math.max(newTriangle[0][0], newTriangle[1][0], newTriangle[2][0]);
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if (maxX - minX < this.sourceWorldWidth_ / 2) {
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triangle.source = newTriangle;
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}
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}
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}.bind(this));
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}
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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 {import("../coordinate.js").Coordinate} a The target a coordinate.
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* @param {import("../coordinate.js").Coordinate} b The target b coordinate.
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* @param {import("../coordinate.js").Coordinate} c The target c coordinate.
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* @param {import("../coordinate.js").Coordinate} aSrc The source a coordinate.
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* @param {import("../coordinate.js").Coordinate} bSrc The source b coordinate.
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* @param {import("../coordinate.js").Coordinate} cSrc The source c coordinate.
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* @private
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*/
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Triangulation.prototype.addTriangle_ = function (a, b, c, 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 {import("../coordinate.js").Coordinate} a The target a coordinate.
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* @param {import("../coordinate.js").Coordinate} b The target b coordinate.
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* @param {import("../coordinate.js").Coordinate} c The target c coordinate.
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* @param {import("../coordinate.js").Coordinate} d The target d coordinate.
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* @param {import("../coordinate.js").Coordinate} aSrc The source a coordinate.
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* @param {import("../coordinate.js").Coordinate} bSrc The source b coordinate.
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* @param {import("../coordinate.js").Coordinate} cSrc The source c coordinate.
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* @param {import("../coordinate.js").Coordinate} dSrc The source d coordinate.
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* @param {number} maxSubdivision Maximal allowed subdivision of the quad.
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* @private
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*/
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Triangulation.prototype.addQuad_ = function (a, b, c, d, aSrc, bSrc, cSrc, dSrc, maxSubdivision) {
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var sourceQuadExtent = boundingExtent([aSrc, bSrc, cSrc, dSrc]);
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var sourceCoverageX = this.sourceWorldWidth_
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? getWidth(sourceQuadExtent) / this.sourceWorldWidth_
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: null;
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var sourceWorldWidth = /** @type {number} */ (this.sourceWorldWidth_);
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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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sourceCoverageX > 0.5 &&
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sourceCoverageX < 1;
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var needsSubdivision = false;
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if (maxSubdivision > 0) {
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if (this.targetProj_.isGlobal() && this.targetWorldWidth_) {
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var targetQuadExtent = boundingExtent([a, b, c, d]);
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var targetCoverageX = getWidth(targetQuadExtent) / this.targetWorldWidth_;
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needsSubdivision =
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targetCoverageX > MAX_TRIANGLE_WIDTH || needsSubdivision;
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}
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if (!wrapsX && this.sourceProj_.isGlobal() && sourceCoverageX) {
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needsSubdivision =
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sourceCoverageX > MAX_TRIANGLE_WIDTH || needsSubdivision;
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}
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}
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if (!needsSubdivision && this.maxSourceExtent_) {
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if (isFinite(sourceQuadExtent[0]) &&
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isFinite(sourceQuadExtent[1]) &&
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isFinite(sourceQuadExtent[2]) &&
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isFinite(sourceQuadExtent[3])) {
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if (!intersects(sourceQuadExtent, 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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}
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var isNotFinite = 0;
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if (!needsSubdivision) {
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if (!isFinite(aSrc[0]) ||
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!isFinite(aSrc[1]) ||
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!isFinite(bSrc[0]) ||
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!isFinite(bSrc[1]) ||
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!isFinite(cSrc[0]) ||
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!isFinite(cSrc[1]) ||
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!isFinite(dSrc[0]) ||
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!isFinite(dSrc[1])) {
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if (maxSubdivision > 0) {
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needsSubdivision = true;
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}
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else {
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// It might be the case that only 1 of the points is infinite. In this case
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// we can draw a single triangle with the other three points
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isNotFinite =
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(!isFinite(aSrc[0]) || !isFinite(aSrc[1]) ? 8 : 0) +
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(!isFinite(bSrc[0]) || !isFinite(bSrc[1]) ? 4 : 0) +
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(!isFinite(cSrc[0]) || !isFinite(cSrc[1]) ? 2 : 0) +
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(!isFinite(dSrc[0]) || !isFinite(dSrc[1]) ? 1 : 0);
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if (isNotFinite != 1 &&
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isNotFinite != 2 &&
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isNotFinite != 4 &&
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isNotFinite != 8) {
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return;
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}
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}
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}
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}
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if (maxSubdivision > 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 = void 0;
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if (wrapsX) {
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var centerSrcEstimX = (modulo(aSrc[0], sourceWorldWidth) +
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modulo(cSrc[0], sourceWorldWidth)) /
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2;
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dx = centerSrcEstimX - modulo(centerSrc[0], sourceWorldWidth);
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}
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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, maxSubdivision - 1);
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this.addQuad_(da, bc, c, d, daSrc, bcSrc, cSrc, dSrc, maxSubdivision - 1);
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}
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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, maxSubdivision - 1);
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this.addQuad_(ab, b, c, cd, abSrc, bSrc, cSrc, cdSrc, maxSubdivision - 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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// Exactly zero or one of *Src is not finite
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// The triangles must have the diagonal line as the first side
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// This is to allow easy code in reproj.s to make it straight for broken
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// browsers that can't handle diagonal clipping
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if ((isNotFinite & 0xb) == 0) {
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this.addTriangle_(a, c, d, aSrc, cSrc, dSrc);
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}
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if ((isNotFinite & 0xe) == 0) {
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this.addTriangle_(a, c, b, aSrc, cSrc, bSrc);
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}
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if (isNotFinite) {
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// Try the other two triangles
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if ((isNotFinite & 0xd) == 0) {
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this.addTriangle_(b, d, a, bSrc, dSrc, aSrc);
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}
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if ((isNotFinite & 0x7) == 0) {
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this.addTriangle_(b, d, c, bSrc, dSrc, cSrc);
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}
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}
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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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*
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* @return {import("../extent.js").Extent} Calculated extent.
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*/
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Triangulation.prototype.calculateSourceExtent = function () {
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var extent = createEmpty();
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this.triangles_.forEach(function (triangle, i, arr) {
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var src = triangle.source;
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extendCoordinate(extent, src[0]);
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extendCoordinate(extent, src[1]);
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extendCoordinate(extent, src[2]);
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});
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return extent;
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};
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/**
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* @return {Array<Triangle>} Array of the calculated triangles.
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*/
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Triangulation.prototype.getTriangles = function () {
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return this.triangles_;
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};
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return Triangulation;
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}());
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export default Triangulation;
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//# sourceMappingURL=Triangulation.js.map
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