/**
 * @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.aVertexPosition);
    gl.disableVertexAttribArray(PIXI.defaultShader.colorAttribute);
    gl.disableVertexAttribArray(PIXI.defaultShader.aTextureCoord);

    gl.enableVertexAttribArray(PIXI.primitiveShader.aVertexPosition);
    gl.enableVertexAttribArray(PIXI.primitiveShader.colorAttribute);
} 

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

    gl.useProgram(PIXI.defaultShader.program);
    
    gl.disableVertexAttribArray(PIXI.primitiveShader.aVertexPosition);
    gl.disableVertexAttribArray(PIXI.primitiveShader.colorAttribute);

    gl.enableVertexAttribArray(PIXI.defaultShader.aVertexPosition);
    gl.enableVertexAttribArray(PIXI.defaultShader.colorAttribute);
    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;
}