DivideBlendFilter.java

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

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

/**
 * Applies a division blend of two images
 * @author Chris Batt
 */
public class DivideBlendFilter extends MultiInputFilter {
	public DivideBlendFilter() {
		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 == 0.0 || ((color1.r / color2.r) > (color1.a / color2.a))) {\n"
		  		+"     r = color2.a * color1.a + color2.r * (1.0 - color1.a) + color1.r * (1.0 - color2.a);\n"
		  		+"   } else {\n"
		  		+"     r = (color1.r * color2.a * color2.a) / color2.r + color2.r * (1.0 - color1.a) + color1.r * (1.0 - color2.a);\n"
	   			+"   }\n"
		  		+"   float g;\n"
		  		+"   if (color2.g == 0.0 || ((color1.g / color2.g) > (color1.a / color2.a))) {\n"
		  		+"     g = color2.a * color1.a + color2.g * (1.0 - color1.a) + color1.g * (1.0 - color2.a);\n"
		  		+"   } else {\n"
		  		+"     g = (color1.g * color2.a * color2.a) / color2.g + color2.g * (1.0 - color1.a) + color1.g * (1.0 - color2.a);\n"
	   			+"   }\n"
		  		+"   float b;\n"
		  		+"   if (color2.b == 0.0 || ((color1.b / color2.b) > (color1.a / color2.a))) {\n"
		  		+"     b = color2.a * color1.a + color2.b * (1.0 - color1.a) + color1.b * (1.0 - color2.a);\n"
		  		+"   } else {\n"
		  		+"     b = (color1.b * color2.a * color2.a) / color2.b + color2.b * (1.0 - color1.a) + color1.b * (1.0 - color2.a);\n"
	   			+"   }\n"
		  		+"   float a  = color2.a + color1.a - color2.a * color1.a;\n"
	   			+"   gl_FragColor = vec4(r, g, b, a);\n"
		  		+"}\n";	
	}
}