SpriteRender.js

/**
	This file contains all the code needed to render a .spr file (Version 2)
	by converting the sprite into a texture.
**/

define(["GameInfo"], function(GameInfo) {
	var fragmentShader = 
	"	precision mediump float;" +
	"	varying vec2 vTexCoord;" +
	"	uniform sampler2D uSampler;" +

	"	void main(void) {" +
	"		gl_FragColor = texture2D(uSampler, vec2(vTexCoord.s, vTexCoord.t));" +
	"	}";
		
	var vertexShader =
	"	attribute vec3 aVertexPosition;" +
	"	attribute vec2 aTexCoord;" +

	"	varying vec2 vTexCoord;" +
		
	"	uniform mat4 uMVMatrix;" +
	"	uniform mat4 uPMatrix;" +

	"	void main(void) {" +
	"		gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);" +
	"		vTexCoord = aTexCoord;" +
	"	}";
		
	return function(gl, sprite) {
		function getShader(gl, shaderCode, shaderType) {
			var shader = gl.createShader(shaderType);

			gl.shaderSource(shader, shaderCode);
			gl.compileShader(shader);

			if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
				alert(gl.getShaderInfoLog(shader));
				return null;
			}

			return shader;
		}
		
		var shaderProgram = (function() {
			var sFragmentShader = getShader(gl, fragmentShader, gl.FRAGMENT_SHADER);
			var sVertexShader = getShader(gl, vertexShader, gl.VERTEX_SHADER);
			
			var program = gl.createProgram();
			gl.attachShader(program, sVertexShader);
			gl.attachShader(program, sFragmentShader);
			gl.linkProgram(program);
			
			if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
				alert("Could not initialise shaders");
			}
			
			gl.useProgram(program);
			program.vertexPositionAttribute = gl.getAttribLocation(program, "aVertexPosition");
			program.texCoordAttribute = gl.getAttribLocation(program, "aTexCoord");

			program.pMatrixUniform = gl.getUniformLocation(program, "uPMatrix");
			program.mvMatrixUniform = gl.getUniformLocation(program, "uMVMatrix");
			program.samplerUniform = gl.getUniformLocation(program, "uSampler");
			
			return program;
		})();
		
		var buffer = gl.createBuffer();

		var texture = gl.createTexture();
		gl.bindTexture(gl.TEXTURE_2D, texture);
		gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, sprite.frames[0].width, sprite.frames[0].height, 0, gl.RGBA, gl.UNSIGNED_BYTE, sprite.frames[0].imageData);
		gl.texParameterf(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
		gl.texParameterf(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
		//Subsprites are not guaranteed to be of size 2^n for some n,
		//so we disable this restriction
		gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
		gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
		
		this.render = function() {
			gl.useProgram(shaderProgram);
			gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);
			gl.enableVertexAttribArray(shaderProgram.texCoordAttribute);
			gl.enable(gl.BLEND);
			gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA);
			gl.disable(gl.DEPTH_TEST);
			
			gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
			var vertices = [
				1.0,  1.0,  0.0,	1.0, 0.0,
				-1.0,  1.0,  0.0,	0.0, 0.0,
				1.0, -1.0,  0.0,	1.0, 1.0,
				-1.0, -1.0,  0.0,	0.0, 1.0
			];
			gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
			
			gl.bindTexture(gl.TEXTURE_2D, texture);
			gl.uniform1i(shaderProgram.samplerUniform, 0);
			
			gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
			gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, 3, gl.FLOAT, false, 20, 0);
			gl.vertexAttribPointer(shaderProgram.texCoordAttribute, 2, gl.FLOAT, false, 20, 12);
			
			//mat4.scale(cs.mvMatrix, cs.mvMatrix, [1/sprite.header.maxWidth, 1/sprite.header.maxHeight, 1]);
			
			gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, GameInfo.pMatrix);
			gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, GameInfo.mvMatrix);
			gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
			
			gl.enable(gl.DEPTH_TEST);
			gl.disable(gl.BLEND);
		};
	};
});