content: /*
   * Copyright (C) 2012 CyberAgent
   *
   * 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.
   */
  
  package jp.co.cyberagent.android.gpuimage;
  
  import android.opengl.GLES20;
  
  /**
   * gamma value ranges from 0.0 to 3.0, with 1.0 as the normal level
   */
  public class GPUImageGammaFilter extends GPUImageFilter {
      public static final String GAMMA_FRAGMENT_SHADER = "" +
              "varying highp vec2 textureCoordinate;\n" +
              " \n" +
              " uniform sampler2D inputImageTexture;\n" +
              " uniform lowp float gamma;\n" +
              " \n" +
              " void main()\n" +
              " {\n" +
              "     lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);\n" +
              "     \n" +
              "     gl_FragColor = vec4(pow(textureColor.rgb, vec3(gamma)), textureColor.w);\n" +
              " }";
  
      private int mGammaLocation;
      private float mGamma;
  
      public GPUImageGammaFilter() {
          this(1.2f);
      }
  
      public GPUImageGammaFilter(final float gamma) {
          super(NO_FILTER_VERTEX_SHADER, GAMMA_FRAGMENT_SHADER);
          mGamma = gamma;
      }
  
      @Override
      public void onInit() {
          super.onInit();
          mGammaLocation = GLES20.glGetUniformLocation(getProgram(), "gamma");
      }
  
      @Override
      public void onInitialized() {
          super.onInitialized();
          setGamma(mGamma);
      }
  
      public void setGamma(final float gamma) {
          mGamma = gamma;
          setFloat(mGammaLocation, mGamma);
      }
  }
  