// =================================================================================================
//
//  Starling Framework
//  Copyright 2012 Gamua OG. All Rights Reserved.
//
//  This program is free software. You can redistribute and/or modify it
//  in accordance with the terms of the accompanying license agreement.
//
// =================================================================================================

package starling.filters
{
    import flash.display3D.Context3D;
    import flash.display3D.Context3DProgramType;
    import flash.display3D.Program3D;

    import starling.textures.Texture;

    public class PixelateFilter extends FragmentFilter
    {
        private var mQuantifiers:Vector.<Number>;
        private var mShaderProgram:Program3D;

        /**
         *
         * @param   pixelSize       size of pixel effect
         * @param   stagewidth      width of stage
         * @param   stageheight     height of stage
         */
        public function PixelateFilter(pixelSize:int, stagewidth:int, stageheight:int)
        {
            var xr:Number = 1 / stagewidth;
            var yr:Number = 1 / stageheight;
            mQuantifiers = new <Number>[pixelSize * xr, pixelSize * yr, 1.0,1.0];
        }

        public override function dispose():void
        {
            if (mShaderProgram) mShaderProgram.dispose();
            super.dispose();
        }

        protected override function createPrograms():void
        {
            var fragmentProgramCode:String =
                "div ft0, v0, fc0                       \n" +
                "frc ft1, ft0                           \n" +
                "sub ft0, ft0, ft1                      \n" +
                "mul ft0, ft0, fc0                      \n" +
                "tex oc, ft0, fs0<2d, clamp, nearest>"

            mShaderProgram = assembleAgal(fragmentProgramCode);
        }

        protected override function activate(pass:int, context:Context3D, texture:Texture):void
        {
            // already set by super class:
            //
            // vertex constants 0-3: mvpMatrix (3D)
            // vertex attribute 0:   vertex position (FLOAT_2)
            // vertex attribute 1:   texture coordinates (FLOAT_2)
            // texture 0:            input texture

            context.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 0, mQuantifiers, 1);
            context.setProgram(mShaderProgram);
        }
    }
}