glInit.js

var gl;
var shaderProgram;

var mvMatrix = mat4.create();
var pMatrix = mat4.create();

function initGL(canvas) {
  try {
    gl = canvas.getContext("experimental-webgl");
    gl.viewportWidth = canvas.width;
    gl.viewportHeight = canvas.height;
  } catch (e) { }
  if (!gl) {
    alert("Could not initialise WebGL, sorry :-(");
  }
}

function initShaders() {
  var fragmentShader = gl.createShader(gl.FRAGMENT_SHADER);
  gl.shaderSource(fragmentShader, fragment_shader_source);
  gl.compileShader(fragmentShader);
  
  if (!gl.getShaderParameter(fragmentShader, gl.COMPILE_STATUS)) {
    alert(gl.getShaderInfoLog(fragmentShader));
    return null;
  }
  
  var vertexShader = gl.createShader(gl.VERTEX_SHADER);
  gl.shaderSource(vertexShader, vertex_shader_source);
  gl.compileShader(vertexShader);
  
  if (!gl.getShaderParameter(vertexShader, gl.COMPILE_STATUS)) {
    alert(gl.getShaderInfoLog(vertexShader));
    return null;
  }
  
  shaderProgram = gl.createProgram();
  gl.attachShader(shaderProgram, vertexShader);
  gl.attachShader(shaderProgram, fragmentShader);
  gl.linkProgram(shaderProgram);
  
  if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
      alert("Could not initialise shaders");
  }
  
  gl.useProgram(shaderProgram);
  
  //shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
  //gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);
  
  //shaderProgram.vertexColorAttribute = gl.getAttribLocation(shaderProgram, "aVertexColor");
  //gl.enableVertexAttribArray(shaderProgram.vertexColorAttribute);
  
  shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
  shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
}

function setMatrixUniforms() {
  gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix);
  gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix);
}