NormalBlendFilter.java

package com.marshalchen.common.uimodule.imageprocessing.filter.blend;

import com.marshalchen.common.uimodule.imageprocessing.filter.MultiInputFilter;

/**
 * Applies a normal blend of two images
 * @author Chris Batt
 */
public class NormalBlendFilter extends MultiInputFilter {
	public NormalBlendFilter() {
		super(2);
	}
	
	@Override
	protected String getFragmentShader() {
		return 
				 "precision mediump float;\n" 
				+"uniform sampler2D "+UNIFORM_TEXTURE0+";\n"  
				+"uniform sampler2D "+UNIFORM_TEXTUREBASE+1+";\n" 
				+"varying vec2 "+VARYING_TEXCOORD+";\n"	
				
		  		+"void main(){\n"
		  		+"   vec4 color2 = texture2D("+UNIFORM_TEXTURE0+","+VARYING_TEXCOORD+");\n"
		  		+"   vec4 color1 = texture2D("+UNIFORM_TEXTUREBASE+1+","+VARYING_TEXCOORD+");\n"
		  		+"   vec4 outputColor;\n"
		  		+"   float a = color1.a + color2.a * (1.0 - color1.a);\n"
		  		+"   outputColor.r = (color1.r * color1.a + color2.r * color2.a * (1.0 - color1.a))/a;\n"
		  		+"   outputColor.g = (color1.g * color1.a + color2.g * color2.a * (1.0 - color1.a))/a;\n"
		  		+"   outputColor.b = (color1.b * color1.a + color2.b * color2.a * (1.0 - color1.a))/a;\n"
		  		+"   outputColor.a = a;\n"
		  		+"   gl_FragColor = outputColor;\n"
		  		+"}\n";	
	}
}