PinchDistortionFilter.java

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

import android.graphics.PointF;

/**
 * Creates a pinch distortion of the image
 * radius: The radius from the center to apply the distortion
 * center: The center of the image (in normalized coordinates from 0 - 1.0) about which to distort)
 * scale: The amount of distortion to apply, from -2.0 to 2.0
 * @author Chris Batt
 */
public class PinchDistortionFilter extends BulgeDistortionFilter {
	public PinchDistortionFilter(PointF center, float radius, float distortionAmount, float aspectRatio) {
		super(center, radius, distortionAmount, aspectRatio);
	}

	@Override
	protected String getFragmentShader() {
		return 
				 "precision mediump float;\n" 
				+"uniform sampler2D "+UNIFORM_TEXTURE0+";\n"  
				+"varying vec2 "+VARYING_TEXCOORD+";\n"	
				+"uniform vec2 "+UNIFORM_CENTER+";\n"
				+"uniform float "+UNIFORM_RADIUS+";\n"
				+"uniform float "+UNIFORM_DISTORTION_AMOUNT+";\n"
				+"uniform float "+UNIFORM_ASPECT_RATIO+";\n"
				
		  		+"void main(){\n"
			    +"   highp vec2 textureCoordinateToUse = vec2("+VARYING_TEXCOORD+".x, ("+VARYING_TEXCOORD+".y * "+UNIFORM_ASPECT_RATIO+" + 0.5 - 0.5 * "+UNIFORM_ASPECT_RATIO+"));\n"
			    +"   highp float dist = distance("+UNIFORM_CENTER+", textureCoordinateToUse);\n" 
			    +"   textureCoordinateToUse = "+VARYING_TEXCOORD+";\n"
			    +"   if (dist < "+UNIFORM_RADIUS+") {\n"
			    +"     textureCoordinateToUse -= "+UNIFORM_CENTER+";\n"
			    +"     highp float percent = 1.0 + ("+UNIFORM_RADIUS+" - dist) / "+UNIFORM_RADIUS+" * "+UNIFORM_DISTORTION_AMOUNT+";\n"
			    +"     textureCoordinateToUse = textureCoordinateToUse * percent;\n"
			    +"     textureCoordinateToUse += "+UNIFORM_CENTER+";\n"
	     		+"   }\n"
			    +"   gl_FragColor = texture2D("+UNIFORM_TEXTURE0+", textureCoordinateToUse);\n"
		  		+"}\n";
	}
}