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;
  
  public class GPUImageNonMaximumSuppressionFilter extends GPUImage3x3TextureSamplingFilter {
      public static final String NMS_FRAGMENT_SHADER = "" +
              "uniform sampler2D inputImageTexture;\n" +
              "\n" +
              "varying highp vec2 textureCoordinate;\n" +
              "varying highp vec2 leftTextureCoordinate;\n" +
              "varying highp vec2 rightTextureCoordinate;\n" +
              "\n" +
              "varying highp vec2 topTextureCoordinate;\n" +
              "varying highp vec2 topLeftTextureCoordinate;\n" +
              "varying highp vec2 topRightTextureCoordinate;\n" +
              "\n" +
              "varying highp vec2 bottomTextureCoordinate;\n" +
              "varying highp vec2 bottomLeftTextureCoordinate;\n" +
              "varying highp vec2 bottomRightTextureCoordinate;\n" +
              "\n" +
              "void main()\n" +
              "{\n" +
              "lowp float bottomColor = texture2D(inputImageTexture, bottomTextureCoordinate).r;\n" +
              "lowp float bottomLeftColor = texture2D(inputImageTexture, bottomLeftTextureCoordinate).r;\n" +
              "lowp float bottomRightColor = texture2D(inputImageTexture, bottomRightTextureCoordinate).r;\n" +
              "lowp vec4 centerColor = texture2D(inputImageTexture, textureCoordinate);\n" +
              "lowp float leftColor = texture2D(inputImageTexture, leftTextureCoordinate).r;\n" +
              "lowp float rightColor = texture2D(inputImageTexture, rightTextureCoordinate).r;\n" +
              "lowp float topColor = texture2D(inputImageTexture, topTextureCoordinate).r;\n" +
              "lowp float topRightColor = texture2D(inputImageTexture, topRightTextureCoordinate).r;\n" +
              "lowp float topLeftColor = texture2D(inputImageTexture, topLeftTextureCoordinate).r;\n" +
              "\n" +
              "// Use a tiebreaker for pixels to the left and immediately above this one\n" +
              "lowp float multiplier = 1.0 - step(centerColor.r, topColor);\n" +
              "multiplier = multiplier * 1.0 - step(centerColor.r, topLeftColor);\n" +
              "multiplier = multiplier * 1.0 - step(centerColor.r, leftColor);\n" +
              "multiplier = multiplier * 1.0 - step(centerColor.r, bottomLeftColor);\n" +
              "\n" +
              "lowp float maxValue = max(centerColor.r, bottomColor);\n" +
              "maxValue = max(maxValue, bottomRightColor);\n" +
              "maxValue = max(maxValue, rightColor);\n" +
              "maxValue = max(maxValue, topRightColor);\n" +
              "\n" +
              "gl_FragColor = vec4((centerColor.rgb * step(maxValue, centerColor.r) * multiplier), 1.0);\n" +
              "}\n";
  
      public GPUImageNonMaximumSuppressionFilter() {
          super(NMS_FRAGMENT_SHADER);
      }
  }
  