gistfile1.as

/**
 *	Copyright (c) 2012 Simon Eyraud
 *
 *	Permission is hereby granted, free of charge, to any person obtaining a copy
 *	of this software and associated documentation files (the "Software"), to deal
 *	in the Software without restriction, including without limitation the rights
 *	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *	copies of the Software, and to permit persons to whom the Software is
 *	furnished to do so, subject to the following conditions:
 *
 *	The above copyright notice and this permission notice shall be included in
 *	all copies or substantial portions of the Software.
 *
 *	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *	THE SOFTWARE.
 */

package
{
	import flash.display3D.Context3D;
	import flash.display3D.Context3DBlendFactor;
	import flash.display3D.Context3DProgramType;
	import flash.display3D.Program3D;
	
	import starling.filters.FragmentFilter;
	import starling.textures.Texture;
	
	public class Shader extends FragmentFilter
	{
		
		private var mShaderProgram:Program3D;
		private var mVars:Vector.<Number> = new <Number>[1,1,1,1];
		
		private var mAlpha:Number;
		
		public function Shader(alpha : Number = 1.0)
		{
			mAlpha = alpha;
		}
		
		public override function dispose():void
		{
			if (mShaderProgram) mShaderProgram.dispose();
			super.dispose();
		}
		
		protected override function createPrograms():void
		{
			var fragmentProgramCode:String =
				"tex ft1, v0, fs0 <2d,linear,nomip>" + "\n" +
				"sub ft1.w, fc0.x, ft1.w" + "\n" +
				"mov oc, ft1"
			
			
			mShaderProgram = assembleAgal(fragmentProgramCode);
		}
		
		protected override function activate(pass:int, context:Context3D, texture:Texture):void
		{		
			mVars[0] = mAlpha;
			
			context.setBlendFactors(Context3DBlendFactor.SOURCE_ALPHA, Context3DBlendFactor.ONE_MINUS_SOURCE_ALPHA);
			context.setProgramConstantsFromVector(Context3DProgramType.FRAGMENT, 0, mVars, 1);
			context.setProgram(mShaderProgram);
		}
		
		override protected function deactivate(pass:int, context:Context3D, texture:Texture):void 
		{
			context.setBlendFactors(Context3DBlendFactor.ONE, Context3DBlendFactor.ZERO);
		}
		
		public function set alpha(value:Number):void { mAlpha = value; }
		public function get alpha():Number { return mAlpha; }
	}
}