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/*
* Copyright (C) 2008 Max Maischein
* Copyright (C) 2013 The CyanogenMod Project
*
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//
// Based in the shaders of Max Maischein of App-VideoMixer:
// http://cpansearch.perl.org/src/CORION/App-VideoMixer-0.02/filters/halftone.glsl
//
package org.cyanogenmod.wallpapers.photophase.effects;
import android.media.effect.EffectContext;
import android.media.effect.EffectFactory;
import android.opengl.GLES20;
import android.util.Log;
import org.cyanogenmod.wallpapers.photophase.utils.GLESUtil;
/**
* A halftone effect<br/>
* <table>
* <tr><td>Parameter name</td><td>Meaning</td><td>Valid values</td></tr>
* <tr>
* <td><code>strength</code></td>
* <td>The halftone steps multiplier.</td>
* <td>Positive float (>0). Higher numbers produce smallest points;</td>
* </tr>
* </table>
*/
public class HalftoneEffect extends PhotoPhaseEffect {
private static final String TAG = "HalftoneEffect";
private static final String STRENGTH_PARAMETER = "strength";
private static final String FRAGMENT_SHADER =
"precision mediump float;\n" +
"uniform sampler2D tex_sampler;\n" +
"varying vec2 v_texcoord;\n" +
"uniform float steps\n;" +
"float dotsize = 1.0 / steps ;\n" +
"float half_step = dotsize / 2.0;\n" +
"void main() {\n" +
" vec2 center = v_texcoord - vec2(mod(v_texcoord.x, dotsize),mod(v_texcoord.y, dotsize)) + half_step;\n" +
" vec4 pel = texture2D(tex_sampler, center);\n" +
" float size = length(pel);\n" +
" if (distance(v_texcoord,center) <= dotsize*size/4.0) {\n" +
" gl_FragColor = pel;\n" +
" } else {\n" +
" gl_FragColor = vec4(0.0,0.0,0.0,0.0);\n" +
" };\n" +
"}\n";
private float mStrength = 32.0f;
private int mStepsHandle;
/**
* An abstract constructor of <code>Effect</code> to follow the rules
* defined by {@link EffectFactory}.
*
* @param ctx The effect context
* @param name The effect name
*/
public HalftoneEffect(EffectContext ctx, String name) {
super(ctx, HalftoneEffect.class.getName());
init(VERTEX_SHADER, FRAGMENT_SHADER);
}
/**
* {@inheritDoc}
*/
@Override
void init(String vertexShader, String fragmentShader) {
super.init(vertexShader, fragmentShader);
// Parameters
mStepsHandle = GLES20.glGetUniformLocation(mProgram, "steps");
GLESUtil.glesCheckError("glGetUniformLocation");
}
/**
* {@inheritDoc}
*/
@Override
void applyParameters() {
// Set parameters
GLES20.glUniform1f(mStepsHandle, mStrength);
GLESUtil.glesCheckError("glUniform1f");
}
/**
* {@inheritDoc}
*/
@Override
public void setParameter(String parameterKey, Object value) {
if (parameterKey.compareTo(STRENGTH_PARAMETER) == 0) {
try {
float strength = Float.parseFloat(value.toString());
if (strength <= 0) {
Log.w(TAG, "strength parameter must be >= 0");
return;
}
mStrength = strength;
} catch (NumberFormatException ex) {
// Ignore
}
}
}
}
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