AddBlendFilter.java

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


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

/**
 * Applies an additive blend of two images
 * @author Chris Batt
 */
public class AddBlendFilter extends MultiInputFilter {
	public AddBlendFilter() {
		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 color1 = texture2D("+UNIFORM_TEXTURE0+","+VARYING_TEXCOORD+");\n"
		  		+"   vec4 color2 = texture2D("+UNIFORM_TEXTUREBASE+1+","+VARYING_TEXCOORD+");\n"
		  		+"   float r;\n"
		  		+"   if (color2.r * color1.a + color1.r * color2.a >= color2.a * color1.a) {\n"
		  		+"     r = color2.a * color1.a + color2.r * (1.0 - color1.a) + color1.r * (1.0 - color2.a);\n"
		  		+"   } else {\n"
		  		+"     r = color2.r + color1.r;\n"
	   			+"   }\n"
		  		+"   float g;\n"
		  		+"   if (color2.g * color1.a + color1.g * color2.a >= color2.a * color1.a) {\n"
		  		+"     g = color2.a * color1.a + color2.g * (1.0 - color1.a) + color1.g * (1.0 - color2.a);\n"
		  		+"   } else {\n"
		  		+"     g = color2.g + color1.g;\n"
	   			+"   }\n"
		  		+"   float b;\n"
		  		+"   if (color2.b * color1.a + color1.b * color2.a >= color2.a * color1.a) {\n"
		  		+"     r = color2.a * color1.a + color2.b * (1.0 - color1.a) + color1.b * (1.0 - color2.a);\n"
		  		+"   } else {\n"
		  		+"     r = color2.b + color1.b;\n"
	   			+"   }\n"
		  		+"   float a  = color2.a + color1.a - color2.a * color1.a;\n"
	   			+"   gl_FragColor = vec4(r, g, b, a);\n"
		  		+"}\n";	
	}
}