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;
  
  /**
   * Adjusts the alpha channel of the incoming image
   * opacity: The value to multiply the incoming alpha channel for each pixel by (0.0 - 1.0, with 1.0 as the default)
  */
  public class GPUImageOpacityFilter extends GPUImageFilter {
      public static final String OPACITY_FRAGMENT_SHADER = "" +
              "  varying highp vec2 textureCoordinate;\n" +
              "  \n" +
              "  uniform sampler2D inputImageTexture;\n" +
              "  uniform lowp float opacity;\n" +
              "  \n" +
              "  void main()\n" +
              "  {\n" +
              "      lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);\n" +
              "      \n" +
              "      gl_FragColor = vec4(textureColor.rgb, textureColor.a * opacity);\n" +
              "  }\n";
  
      private int mOpacityLocation;
      private float mOpacity;
  
      public GPUImageOpacityFilter() {
          this(1.0f);
      }
  
      public GPUImageOpacityFilter(final float opacity) {
          super(NO_FILTER_VERTEX_SHADER, OPACITY_FRAGMENT_SHADER);
          mOpacity = opacity;
      }
  
      @Override
      public void onInit() {
          super.onInit();
          mOpacityLocation = GLES20.glGetUniformLocation(getProgram(), "opacity");
      }
  
      @Override
      public void onInitialized() {
          super.onInitialized();
          setOpacity(mOpacity);
      }
  
      public void setOpacity(final float opacity) {
          mOpacity = opacity;
          setFloat(mOpacityLocation, mOpacity);
      }
  }
  