Add atlas manager
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tsauerwein
@@ -0,0 +1,306 @@
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goog.provide('ol.renderer.webgl.Atlas');
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goog.provide('ol.renderer.webgl.AtlasManager');
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goog.require('goog.asserts');
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goog.require('goog.dom');
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goog.require('goog.dom.TagName');
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goog.require('goog.object');
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/**
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* @constructor
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* @struct
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* @param {number} offsetX
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* @param {number} offsetY
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* @param {HTMLCanvasElement} image
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*/
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ol.renderer.webgl.AtlasInfo = function(offsetX, offsetY, image) {
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/**
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* @type {number}
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*/
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this.offsetX = offsetX;
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/**
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* @type {number}
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*/
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this.offsetY = offsetY;
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/**
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* @type {HTMLCanvasElement}
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*/
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this.image = image;
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};
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/**
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* @constructor
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* @struct
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* @param {number=} opt_size The size in pixels of the sprite images
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* (default: 256).
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* @param {number=} opt_space The space in pixels between images
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* (default: 1).
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*/
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ol.renderer.webgl.AtlasManager = function(opt_size, opt_space) {
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/**
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* The size in pixels of the sprite images.
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* @private
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* @type {number}
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*/
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this.size_ = goog.isDef(opt_size) ? opt_size : 256;
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/**
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* The size in pixels between images.
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* @private
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* @type {number}
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*/
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this.space_ = goog.isDef(opt_space) ? opt_space : 1;
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/**
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* @private
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* @type {Array.<ol.renderer.webgl.Atlas>}
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*/
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this.atlases_ = [new ol.renderer.webgl.Atlas(this.size_, this.space_)];
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};
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/**
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* @param {number} hash The hash of the entry to check.
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* @return {ol.renderer.webgl.AtlasInfo}
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*/
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ol.renderer.webgl.AtlasManager.prototype.getInfo = function(hash) {
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var atlas, info;
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for (var i = 0, l = this.atlases_.length; i < l; i++) {
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atlas = this.atlases_[i];
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info = atlas.get(hash);
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if (info !== null) {
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return info;
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}
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}
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return null;
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};
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/**
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* Add an image to the atlas manager.
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*
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* If an entry for the given hash already exists, the entry will
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* be overridden (but the space on the atlas graphic will not be freed).
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*
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* @param {number} hash The hash of the entry to add.
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* @param {number} width The width.
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* @param {number} height The height.
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* @param {function(*)} renderCallback Called to render the new sprite entry
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* onto the sprite image.
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* @param {object=} opt_this Value to use as `this` when executing
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* `renderCallback`.
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* @return {ol.renderer.webgl.AtlasInfo}
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*/
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ol.renderer.webgl.AtlasManager.prototype.add =
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function(hash, width, height, renderCallback, opt_this) {
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goog.asserts.assert(width <= this.size_ && height <= this.size_,
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'the entry is too big for the current atlas size');
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var atlas, info;
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for (var i = 0, l = this.atlases_.length; i < l; i++) {
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atlas = this.atlases_[i];
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info = atlas.add(hash, width, height, renderCallback, opt_this);
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if (info !== null) {
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return info;
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}
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}
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// the entry could not be added to one of the existing atlases,
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// create a new atlas and add to this one.
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// TODO double the size and check for max. size?
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atlas = new ol.renderer.webgl.Atlas(this.size_, this.space_);
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this.atlases_.push(atlas);
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return atlas.add(hash, width, height, renderCallback, opt_this);
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};
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/**
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* This class facilitates the creation of texture atlases.
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*
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* Images added to an atlas will be rendered onto a single
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* atlas canvas. The distribution of images on the canvas are
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* managed with the bin packing algorithm described in:
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* http://www.blackpawn.com/texts/lightmaps/
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*
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* @constructor
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* @struct
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* @param {number} size The size in pixels of the sprite images.
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* @param {number} space The space in pixels between images.
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*/
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ol.renderer.webgl.Atlas = function(size, space) {
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/**
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* @private
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* @type {number} The space in pixels between images.
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* Because texture coordinates are float values, the edges of
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* texture might not be completely correct (in a way that the
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* edges overlap when being rendered). To avoid this we add a
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* padding around each image.
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*/
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this.space_ = space;
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/**
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* @private
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* @type {Array.<ol.renderer.webgl.Atlas.Block>}
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*/
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this.emptyBlocks_ = [{x: 0, y: 0, width: size, height: size}];
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/**
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* @private
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* @type {Object.<number, ol.renderer.webgl.AtlasInfo>}
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*/
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this.entries_ = {};
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/**
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* @private
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* @type {HTMLCanvasElement}
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*/
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this.canvas_ = /** @type {HTMLCanvasElement} */
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(goog.dom.createElement(goog.dom.TagName.CANVAS));
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this.canvas_.width = size;
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this.canvas_.height = size;
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/**
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* @private
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* @type {CanvasRenderingContext2D}
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*/
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this.context_ = /** @type {CanvasRenderingContext2D} */
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(this.canvas_.getContext('2d'));
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};
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/**
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* @param {number} hash The hash of the entry to check.
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* @return {ol.renderer.webgl.AtlasInfo}
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*/
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ol.renderer.webgl.Atlas.prototype.get = function(hash) {
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return goog.object.get(this.entries_, hash, null);
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};
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/**
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* @param {number} hash The hash of the entry to add.
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* @param {number} width The width.
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* @param {number} height The height.
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* @param {function(*)} renderCallback Called to render the new sprite entry
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* onto the sprite image.
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* @param {object=} opt_this Value to use as `this` when executing
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* `renderCallback`.
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* @return {ol.renderer.webgl.AtlasInfo}
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*/
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ol.renderer.webgl.Atlas.prototype.add =
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function(hash, width, height, renderCallback, opt_this) {
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var block;
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for (var i = 0, l = this.emptyBlocks_.length; i < l; i++) {
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block = this.emptyBlocks_[i];
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if (block.width >= width + this.space_ &&
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block.height >= height + this.space_) {
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// we found a block that is big enough for our entry
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var entry = new ol.renderer.webgl.AtlasInfo(
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block.x + this.space_, block.y + this.space_, this.canvas_);
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this.entries_[hash] = entry;
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// render the image on the atlas image
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renderCallback.call(opt_this, this.context_,
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block.x + this.space_, block.y + this.space_);
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// split the block after the insertion, either horizontally or vertically
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this.split_(i, block, width + this.space_, height + this.space_);
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return entry;
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}
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}
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// there is no space for the new entry in this atlas
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return null;
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};
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/**
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* @private
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* @param {number} index The index of the block.
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* @param {ol.renderer.webgl.Atlas.Block} block The block to split.
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* @param {number} width The width of the entry to insert.
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* @param {number} height The height of the entry to insert.
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*/
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ol.renderer.webgl.Atlas.prototype.split_ =
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function(index, block, width, height) {
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var deltaWidth = block.width - width;
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var deltaHeight = block.height - height;
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var newBlock1, newBlock2;
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if (deltaWidth > deltaHeight) {
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// split vertically
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// block right of the inserted entry
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newBlock1 = {
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x: block.x + width,
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y: block.y,
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width: block.width - width,
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height: block.height
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};
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// block below the inserted entry
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newBlock2 = {
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x: block.x,
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y: block.y + height,
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width: width,
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height: block.height - height
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};
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this.updateBlocks_(index, newBlock1, newBlock2);
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} else {
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// split horizontally
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// block right of the inserted entry
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newBlock1 = {
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x: block.x + width,
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y: block.y,
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width: block.width - width,
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height: height
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};
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// block below the inserted entry
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newBlock2 = {
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x: block.x,
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y: block.y + height,
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width: block.width,
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height: block.height - height
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};
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this.updateBlocks_(index, newBlock1, newBlock2);
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}
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};
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/**
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* Remove the old block and insert new blocks at the same array position.
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* The new blocks are inserted at the same position, so that splitted
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* blocks (that are potentially smaller) are filled first.
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* @private
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* @param {number} index The index of the block to remove.
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* @param {ol.renderer.webgl.Atlas.Block} newBlock1 The 1st block to add.
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* @param {ol.renderer.webgl.Atlas.Block} newBlock2 The 2nd block to add.
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*/
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ol.renderer.webgl.Atlas.prototype.updateBlocks_ =
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function(index, newBlock1, newBlock2) {
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var args = [index, 1];
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if (newBlock1.width > 0 && newBlock1.height > 0) {
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args.push(newBlock1);
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}
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if (newBlock2.width > 0 && newBlock2.height > 0) {
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args.push(newBlock2);
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}
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this.emptyBlocks_.splice.apply(this.emptyBlocks_, args);
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};
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/**
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* @typedef{{x: number, y: number, width: number, height: number}}
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*/
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ol.renderer.webgl.Atlas.Block;
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