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;
  
  public class GPUImageLaplacianFilter extends GPUImage3x3TextureSamplingFilter {
      public static final String LAPLACIAN_FRAGMENT_SHADER = "" +
              "precision highp float;\n" +
              "\n" +
              "uniform sampler2D inputImageTexture;\n" +
              "\n" +
              "uniform mediump mat3 convolutionMatrix;\n" +
              "\n" +
              "varying vec2 textureCoordinate;\n" +
              "varying vec2 leftTextureCoordinate;\n" +
              "varying vec2 rightTextureCoordinate;\n" +
              "\n" +
              "varying vec2 topTextureCoordinate;\n" +
              "varying vec2 topLeftTextureCoordinate;\n" +
              "varying vec2 topRightTextureCoordinate;\n" +
              "\n" +
              "varying vec2 bottomTextureCoordinate;\n" +
              "varying vec2 bottomLeftTextureCoordinate;\n" +
              "varying vec2 bottomRightTextureCoordinate;\n" +
              "\n" +
              "void main()\n" +
              "{\n" +
              "mediump vec3 bottomColor = texture2D(inputImageTexture, bottomTextureCoordinate).rgb;\n" +
              "mediump vec3 bottomLeftColor = texture2D(inputImageTexture, bottomLeftTextureCoordinate).rgb;\n" +
              "mediump vec3 bottomRightColor = texture2D(inputImageTexture, bottomRightTextureCoordinate).rgb;\n" +
              "mediump vec4 centerColor = texture2D(inputImageTexture, textureCoordinate);\n" +
              "mediump vec3 leftColor = texture2D(inputImageTexture, leftTextureCoordinate).rgb;\n" +
              "mediump vec3 rightColor = texture2D(inputImageTexture, rightTextureCoordinate).rgb;\n" +
              "mediump vec3 topColor = texture2D(inputImageTexture, topTextureCoordinate).rgb;\n" +
              "mediump vec3 topRightColor = texture2D(inputImageTexture, topRightTextureCoordinate).rgb;\n" +
              "mediump vec3 topLeftColor = texture2D(inputImageTexture, topLeftTextureCoordinate).rgb;\n" +
              "\n" +
              "mediump vec3 resultColor = topLeftColor * convolutionMatrix[0][0] + topColor * convolutionMatrix[0][1] + topRightColor * convolutionMatrix[0][2];\n" +
              "resultColor += leftColor * convolutionMatrix[1][0] + centerColor.rgb * convolutionMatrix[1][1] + rightColor * convolutionMatrix[1][2];\n" +
              "resultColor += bottomLeftColor * convolutionMatrix[2][0] + bottomColor * convolutionMatrix[2][1] + bottomRightColor * convolutionMatrix[2][2];\n" +
              "\n" +
              "// Normalize the results to allow for negative gradients in the 0.0-1.0 colorspace\n" +
              "resultColor = resultColor + 0.5;\n" +
              "\n" +
              "gl_FragColor = vec4(resultColor, centerColor.a);\n" +
              "}\n";
  
      private float[] mConvolutionKernel;
      private int mUniformConvolutionMatrix;
  
      public GPUImageLaplacianFilter() {
          this(new float[]{
                  0.5f, 1.0f, 0.5f,
                  1.0f, -6.0f, 1.0f,
                  0.5f, 1.0f, 0.5f
          });
      }
  
      private GPUImageLaplacianFilter(final float[] convolutionKernel) {
          super(LAPLACIAN_FRAGMENT_SHADER);
          mConvolutionKernel = convolutionKernel;
      }
  
      @Override
      public void onInit() {
          super.onInit();
          mUniformConvolutionMatrix = GLES20.glGetUniformLocation(getProgram(), "convolutionMatrix");
          setConvolutionKernel(mConvolutionKernel);
      }
  
      private void setConvolutionKernel(final float[] convolutionKernel) {
          mConvolutionKernel = convolutionKernel;
          setUniformMatrix3f(mUniformConvolutionMatrix, mConvolutionKernel);
      }
  }
  