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;
  
  /**
   * Applies a grayscale effect to the image.
   */
  public class GPUImageGrayscaleFilter extends GPUImageFilter {
      public static final String GRAYSCALE_FRAGMENT_SHADER = "" +
              "precision highp float;\n" +
              "\n" +
              "varying vec2 textureCoordinate;\n" +
              "\n" +
              "uniform sampler2D inputImageTexture;\n" +
              "\n" +
              "const highp vec3 W = vec3(0.2125, 0.7154, 0.0721);\n" +
              "\n" +
              "void main()\n" +
              "{\n" +
              "  lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);\n" +
              "  float luminance = dot(textureColor.rgb, W);\n" +
              "\n" +
              "  gl_FragColor = vec4(vec3(luminance), textureColor.a);\n" +
              "}";
  
      public GPUImageGrayscaleFilter() {
          super(NO_FILTER_VERTEX_SHADER, GRAYSCALE_FRAGMENT_SHADER);
      }
  }
  