WebGL shader utilities

glShaderUtils.js

/*
 * Copyright (c) 2011 Michael Nischt
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of the project's author nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

function getProgramAttributes(gl, program, attributes) {
    attributes = attributes || {};

    var info, i, count = gl.getProgramParameter(program, gl.ACTIVE_ATTRIBUTES);
    for (i = 0; i < count; i += 1) {
        info = gl.getActiveAttrib(program, i);
        attributes[info.name] = gl.getAttribLocation(program, info.name);
    }
    return attributes;
}
function getProgramUniforms(gl, program, uniforms) {
    uniforms = uniforms || {};

    var info, i, count = gl.getProgramParameter(program, gl.ACTIVE_UNIFORMS);
    for (i = 0; i < count; i += 1) {
        info = gl.getActiveUniform(program, i);
        uniforms[info.name] = gl.getUniformLocation(program, info.name);
    }
    return uniforms;
}
function getProgramParameters(gl, program, parameters) {
    parameters = parameters || {};
    parameters.uniforms = getProgramUniforms(gl, program);
    parameters.attributes = getProgramAttributes(gl, program);
    return parameters;
}

function createShader(gl, str, shaderType) {
    var shader = gl.createShader(shaderType);

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

    if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
        throw ("GLSL compile error:\n" + gl.getShaderInfoLog(shader));
    }
    return shader;
}
function createVertexShader(gl, str) {
    return createShader(gl, str, gl.VERTEX_SHADER);
}
function createFragmentShader(gl, str) {
    return createShader(gl, str, gl.FRAGMENT_SHADER);
}

function createProgram(gl, vertexShader, fragmentShader) {
    var program = gl.createProgram();

    gl.attachShader(program, vertexShader);
    gl.attachShader(program, fragmentShader);
    gl.linkProgram(program);

    if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
        throw ("GLSL link error:\n" + gl.getProgramInfoLog(program));
    }
    return program;
}
function createProgramFromSource(gl, vs, fs) {
    vs = GL.createVertexShader(gl, vs);
    fs = GL.createFragmentShader(gl, fs);
    return GL.createProgram(gl, vs, fs);
}