flow.js

/* Copyright (c) 2009-2010 King Abdullah University of Science and Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/* This class encapsulates the flow primitive.
 */
function flow(string, options) {
	
	this.gl   = null;
	this.f    = string;
	
	/* This is one way in which the WebGL implementation of OpenGLot
	 * differs greatly from the C++ implementatiln.  WebGL (OpenGL 
	 * ES 2.0) does not support display lists, and instead I've moved
	 * the implementation to use vertex-buffer objects.  These are
	 * those.
	 */
	this.vertexVBO	= null;
	this.textureVBO = null;
	this.indexVBO	= null;
	
	/* A more apt name might be "resolution," as count is the number
	 * of samples along each axis (x and y) samples are taken. Being
	 * set to 100 means that it will produce 2 * 100 * 100 triangles.
	 */
	this.count		= 250;
	this.index_ct   = 0;
	
	this.source = null;
	this.ping   = null;
	this.pong   = null;
	this.fbo    = null;
	
	this.texture = null;

	/* This will likely be depricated, but it currently is hidden from
	 * the end programmer.
	 */
	this.initialize = function(gl, scr, parameters) {
		this.gl = gl;
		this.parameters = parameters;
		this.refresh(scr);
		this.gen_program();
	}
	
	/* Refresh is a way for the grapher instance to notify surface of
	 * changes to the viewing environment.  All the new information is
	 * contained in the screen object passed in, including the minimum
	 * and maximum x and y values for the surface. In the 3D implemen-
	 * tation, it's not commonly-used.
	 */
	this.refresh = function(scr) {
		this.gen_vbo(scr);
		
		if (this.ping) {
			// Delete texture
		}
		
		if (this.pong) {
			// Delete texture
		}
		
		if ((!this.source) || scr.width > (this.source.width * 2 + 100) || scr.height > (this.source.height * 2 + 100)) {
			console.log("Creating texture of size " + scr.width + " x " + scr.height);
			
			this.ping = new emptytexture(this.gl, scr.width, scr.height);
			//this.ping = new texture(this.gl, "textures/kaust.png").texture;
			this.pong = new emptytexture(this.gl, scr.width, scr.height);
			//this.pong = new texture(this.gl, "textures/kaust.png").texture;
			//this.source = new noisetexture(this.gl, scr.width / 2, scr.height / 2);
			//this.source = new texture(this.gl, "textures/kaust.png").texture;
			
			f = function(pixels) {
				var count = scr.width * scr.height * 4;
				for (var i = 0; i < count; i += 4) {
					pixels[i] = Math.random() * 3.0;
				}
				return pixels;
			}
			
			this.source = new ftexture(this.gl, scr.width / 2, scr.height / 2, f, this.gl.RGBA);
			
			this.gl.bindTexture(this.gl.TEXTURE_2D, null);
		}
		
		if (!this.fbo) {
			this.fbo = this.gl.createFramebuffer();
		}
	}

	/* All primitives are responsible for knowing how to construct them-
	 * selves and so this is the function that constructs the VBO for
	 * the objects.
	 */
	this.gen_vbo = function(scr) {
		var vertices = [];
		var texture  = [];
		var indices  = [];
		
		var x = scr.minx;
		var y = scr.miny;
		var tx = 0.0;
		var ty = 0.0;
		
		var dx = (scr.maxx - scr.minx) / this.count;
		var dy = (scr.maxy - scr.miny) / this.count;
		var dt = 1.0 / this.count;
		
		var i = 0;
		var j = 0;
		
		/* This could probably still be optimized, but at least it's now
		 * using a single triangle strip to render the mesh.  Much better
		 * than the alternative.
		 */
		for (i = 0; i <= this.count; ++i) {
			y = scr.miny;
			ty = 0.0;
			for (j = 0; j <= this.count; ++j) {
				vertices.push(x);
				vertices.push(y);
				texture.push(tx);
				texture.push(ty);
				
				y += dy;
				ty += dt;
			}
			x += dx;
			tx += dt;
		}
		
		var c = 0;
		indices.push(c)
		
		var inc = this.count + 1;
		var dec = inc - 1;
		
		for (i = 0; i < this.count; ++i) {
			for (j = 0; j < this.count; ++j) {
				c += inc;
				indices.push(c);
				c -= dec;
				indices.push(c);
			}
			c += inc;
			indices.push(c);
			indices.push(c);
			
			if (dec < inc) {
				dec = inc + 1;
			} else {
				dec = inc - 1;
			}
		}

		/* Again, I'm not an expert in JavaScript, and I'm currently not
		 * sure how exactly garbage collection works.  Either way, when 
		 * generating the VBO, it's a good idea to delete the previously-
		 * declared VBO so that it frees up some space on the GPU.  This
		 * will be added soon, when I can find a tool that helps me track
		 * and make sure that this memory is getting cleaned up.
		 */
		/*
		if (this.vertexVBO) {
			this.gl.console.log("deleting");
			this.gl.deleteBuffer(this.vertexVBO);
		}
		*/
		
		this.vertexVBO = this.gl.createBuffer();
		this.gl.bindBuffer(this.gl.ARRAY_BUFFER, this.vertexVBO);
		this.gl.bufferData(this.gl.ARRAY_BUFFER, new WebGLFloatArray(vertices), this.gl.STATIC_DRAW);

		/* One of the options (currently anticipated from this version) is
		 * to color the surface with a normal map or a regular texture and
		 * lighting information for the perception of depth on the object.
		 */
		this.textureVBO = this.gl.createBuffer();
		this.gl.bindBuffer(this.gl.ARRAY_BUFFER, this.textureVBO);
		this.gl.bufferData(this.gl.ARRAY_BUFFER, new WebGLFloatArray(texture), this.gl.STATIC_DRAW);
		
		this.indexVBO = this.gl.createBuffer();
		this.gl.bindBuffer(this.gl.ELEMENT_ARRAY_BUFFER, this.indexVBO);
		this.gl.bufferData(this.gl.ELEMENT_ARRAY_BUFFER, new WebGLUnsignedShortArray(indices), this.gl.STATIC_DRAW);
		
		this.index_ct = indices.length;
	}
	
	this.calculate = function(scr) {
    this.gl.uniform1i(this.gl.getUniformLocation(this.program, "accumulation"), 0);
		this.gl.uniform1i(this.gl.getUniformLocation(this.program, "source"), 1);
		
		this.gl.enableVertexAttribArray(0);
		this.gl.enableVertexAttribArray(1);
		
		this.gl.bindBuffer(this.gl.ARRAY_BUFFER, this.vertexVBO);
		this.gl.vertexAttribPointer(0, 2, this.gl.FLOAT, this.gl.FALSE, 0, 0);
		
		// More texture support
		this.gl.bindBuffer(this.gl.ARRAY_BUFFER, this.textureVBO);
		this.gl.vertexAttribPointer(1, 2, this.gl.FLOAT, this.gl.FALSE, 0, 0);
		
		this.gl.bindBuffer(this.gl.ELEMENT_ARRAY_BUFFER, this.indexVBO);
		
		var tmp = this.ping;
		this.ping = this.pong;
		this.pong = tmp;
		
		// First, set up Framebuffer we'll render into
		this.gl.bindFramebuffer(this.gl.FRAMEBUFFER, this.fbo);
		this.gl.framebufferTexture2D(this.gl.FRAMEBUFFER, this.gl.COLOR_ATTACHMENT0, this.gl.TEXTURE_2D, this.ping, 0);
		
		this.gl.enable(this.gl.TEXTURE_2D);
		this.gl.activeTexture(this.gl.TEXTURE0);
		this.gl.bindTexture(this.gl.TEXTURE_2D, this.pong);
		this.gl.activeTexture(this.gl.TEXTURE1);
		this.gl.bindTexture(this.gl.TEXTURE_2D, this.source);
		this.checkFramebuffer();
		
		// Then drawing the triangle strip using the calc program
		this.gl.drawElements(this.gl.TRIANGLE_STRIP, this.index_ct, this.gl.UNSIGNED_SHORT, 0);
		
		/*
		scr.set_uniforms(this.gl, this.program);
		// Then, on top of that, draw the current line set
		this.gl.useProgram(this.program);
		this.gl.drawElements(this.gl.LINE_STRIP, this.index_ct, this.gl.UNSIGNED_SHORT, 0);
		//*/
				
		this.gl.disableVertexAttribArray(0);
		this.gl.disableVertexAttribArray(1);
	}
	
	/* Every primitive is also responsible for knowing how to draw itself,
	 * and that behavior is encapsulated in this function. It should be 
	 * completely self-contained, returning the context state to what it
	 * was before it's called.
	 */
	this.draw = function(scr) {
		this.setUniforms(scr);
		
		this.calculate(scr);
		this.calculate(scr);		

		this.gl.uniform1i(this.gl.getUniformLocation(this.program, "accumulation"), 0);
		
		this.gl.enableVertexAttribArray(0);
		this.gl.enableVertexAttribArray(1);
		
		this.gl.bindBuffer(this.gl.ARRAY_BUFFER, this.vertexVBO);
		this.gl.vertexAttribPointer(0, 2, this.gl.FLOAT, this.gl.FALSE, 0, 0);
		
		// More texture support
		this.gl.bindBuffer(this.gl.ARRAY_BUFFER, this.textureVBO);
		this.gl.vertexAttribPointer(1, 2, this.gl.FLOAT, this.gl.FALSE, 0, 0);
		
		this.gl.bindBuffer(this.gl.ELEMENT_ARRAY_BUFFER, this.indexVBO);
		
		// Now, render into the normal render buffer, referencing
		this.gl.bindFramebuffer(this.gl.FRAMEBUFFER, null);
		
		// the recently-drawn texture
		this.gl.enable(this.gl.TEXTURE_2D);
		this.gl.activeTexture(this.gl.TEXTURE0);
		this.gl.bindTexture(this.gl.TEXTURE_2D, this.ping);
		this.gl.drawElements(this.gl.TRIANGLE_STRIP, this.index_ct, this.gl.UNSIGNED_SHORT, 0);
		//*/
		
		this.gl.disableVertexAttribArray(0);
		this.gl.disableVertexAttribArray(1);
		
	}
	
	/* Any class who inherits from the primitive class gets free access
	 * to shader compilation and program linking, but only must provide
	 * the fragment and vertex shader sources.  The primitive class also
	 * provides free access to functionality for reading files.
	 */
	this.gen_program = function() {
		var vertex_source = this.read("shaders/flow.vert").replace("USER_FUNCTION", this.f);
		var frag_source   = this.read("shaders/flow.frag").replace("USER_FUNCTION", this.f);

		this.program = this.compile_program(vertex_source, frag_source);
	}
}

flow.prototype = new primitive();