FastBlurFilter.java

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

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

/**
 * A hardware-accelerated 9-hit Gaussian blur of an image
 * @author Chris Batt
 */
public class FastBlurFilter extends TwoPassMultiPixelFilter {		
	@Override
	protected String getFragmentShader() {
		return 
				 "precision mediump float;\n" 
				+"uniform sampler2D "+UNIFORM_TEXTURE0+";\n"  
				+"varying vec2 "+VARYING_TEXCOORD+";\n"	
				+"uniform float "+UNIFORM_TEXELWIDTH+";\n"
				+"uniform float "+UNIFORM_TEXELHEIGHT+";\n"
						
				
		  		+"void main(){\n"
		  		+"   vec2 firstOffset = vec2(1.3846153846 * "+UNIFORM_TEXELWIDTH+", 1.3846153846 * "+UNIFORM_TEXELHEIGHT+");\n"
		  		+"   vec2 secondOffset = vec2(3.2307692308 * "+UNIFORM_TEXELWIDTH+", 3.2307692308 * "+UNIFORM_TEXELHEIGHT+");\n"
				+"   vec3 sum = vec3(0,0,0);\n"
		  		+"   vec4 color = texture2D("+UNIFORM_TEXTURE0+", "+VARYING_TEXCOORD+");\n"
				+"   sum += color.rgb * 0.2270270270;\n"
				+"   sum += texture2D("+UNIFORM_TEXTURE0+", "+VARYING_TEXCOORD+" - firstOffset).rgb * 0.3162162162;\n"
				+"   sum += texture2D("+UNIFORM_TEXTURE0+", "+VARYING_TEXCOORD+" + firstOffset).rgb * 0.3162162162;\n"
				+"   sum += texture2D("+UNIFORM_TEXTURE0+", "+VARYING_TEXCOORD+" - secondOffset).rgb * 0.0702702703;\n"
				+"   sum += texture2D("+UNIFORM_TEXTURE0+", "+VARYING_TEXCOORD+" + secondOffset).rgb * 0.0702702703;\n"
		  		+"   gl_FragColor = vec4(sum, color.a);\n"
		  		+"}\n";
	}
}