/**
 * @author Mat Groves http://matgroves.com/ @Doormat23
 */


PIXI.initDefaultShaders = function() 
{
	PIXI.primitiveShader = new PIXI.PrimitiveShader();
  PIXI.primitiveShader.init();

  PIXI.stripShader = new PIXI.StripShader();
  PIXI.stripShader.init();

	PIXI.defaultShader = new PIXI.PixiShader();
	PIXI.defaultShader.init();

  var gl = PIXI.gl; 
  var shaderProgram = PIXI.defaultShader.program;
 

  gl.useProgram(shaderProgram);
  
  gl.enableVertexAttribArray(PIXI.defaultShader.aVertexPosition);
  gl.enableVertexAttribArray(PIXI.defaultShader.colorAttribute);
  gl.enableVertexAttribArray(PIXI.defaultShader.aTextureCoord);
}

PIXI.activatePrimitiveShader = function()
{
  var gl = PIXI.gl;
  
  gl.useProgram(PIXI.primitiveShader.program);
  gl.disableVertexAttribArray(PIXI.defaultShader.aTextureCoord);
} 

PIXI.deactivatePrimitiveShader = function()
{
  var gl = PIXI.gl;

  gl.useProgram(PIXI.defaultShader.program);
  gl.enableVertexAttribArray(PIXI.defaultShader.aTextureCoord);
}

PIXI.activateStripShader = function()
{
  var gl = PIXI.gl;
  
  gl.useProgram(PIXI.stripShader.program);
 // gl.disableVertexAttribArray(PIXI.defaultShader.aTextureCoord);
} 

PIXI.deactivateStripShader = function()
{
  var gl = PIXI.gl;

  gl.useProgram(PIXI.defaultShader.program);
  //gl.enableVertexAttribArray(PIXI.defaultShader.aTextureCoord);
}

/*

SHADER COMPILER HELPERS
*/

PIXI.CompileVertexShader = function(gl, shaderSrc)
{
  return PIXI._CompileShader(gl, shaderSrc, gl.VERTEX_SHADER);
}

PIXI.CompileFragmentShader = function(gl, shaderSrc)
{
  return PIXI._CompileShader(gl, shaderSrc, gl.FRAGMENT_SHADER);
}

PIXI._CompileShader = function(gl, shaderSrc, shaderType)
{
  var src = shaderSrc.join("\n");
  var shader = gl.createShader(shaderType);
  gl.shaderSource(shader, src);
  gl.compileShader(shader);

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

  return shader;
}


PIXI.compileProgram = function(vertexSrc, fragmentSrc)
{
	var gl = PIXI.gl;
	var fragmentShader = PIXI.CompileFragmentShader(gl, fragmentSrc);
	var vertexShader = PIXI.CompileVertexShader(gl, vertexSrc);
	
	var shaderProgram = gl.createProgram();
	
    gl.attachShader(shaderProgram, vertexShader);
    gl.attachShader(shaderProgram, fragmentShader);
    gl.linkProgram(shaderProgram);

    if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
        console.log("Could not initialise shaders");
    }

	return shaderProgram;
}