Android Open Source - FxCameraApp Gl Harris Corner Detection Shader

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From Project

Back to project page FxCameraApp.

License

The source code is released under:

MIT License

Java Source Code

package com.af.experiments.FxCameraApp.shaders;
// w ww. ja  v a  2 s  . co m

import static android.opengl.GLES20.glUniform1f;

public class GlHarrisCornerDetectionShader extends GlShader {

  private static final String FRAGMENT_SHADER =
      "precision mediump float;\n" +   // ?????????????????

      "varying highp vec2 vTextureCoord;" +
      "uniform lowp sampler2D sTexture;" +
      "uniform lowp float sensitivity;" +

      "const mediump float harrisConstant = 0.04;" +

      "void main() {" +
        "mediump vec3 derivativeElements = texture2D(sTexture, vTextureCoord).rgb;" +
        "mediump float derivativeSum = derivativeElements.x + derivativeElements.y;" +

        // R = (Ix^2 * Iy^2 - Ixy * Ixy) / (Ix^2 + Iy^2)
        "mediump float zElement = (derivativeElements.z * 2.0) - 1.0;" +
        "mediump float cornerness = derivativeElements.x * derivativeElements.y - (zElement * zElement) - harrisConstant * derivativeSum * derivativeSum;" +

        "gl_FragColor = vec4(vec3(cornerness * sensitivity), 1.0);" +
      "}";

  private float mSensitivity = 5.0f;

  public GlHarrisCornerDetectionShader() {
    super(DEFAULT_VERTEX_SHADER, FRAGMENT_SHADER);
  }
  protected String mShaderName = "Harris CD";

  public String getName() {
    return mShaderName;
  }


  public float getSensitivity() {
    return mSensitivity;
  }

  public void setSensitivity(final float sensitivity) {
    mSensitivity = sensitivity;
  }


  @Override
  public void onDraw() {
    glUniform1f(getHandle("sensitivity"), mSensitivity);
  }

}

Java Source Code List

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