opengl相机通过shader修改片断着色器来实现换色，改色，肤色检测等特殊效果

1.嘴唇检测并改掉色，不准确时可能和相同有关，关于嘴唇颜色检测参考文章

https://blog.csdn.net/Trent1985/article/details/46330847

 private static final String CAMERA_INPUT_FRAGMENT_SHADER_OES = "" +             "#extension GL_OES_EGL_image_external : require\n" +             "\n" +             "precision mediump float;\n" +             "varying vec2 textureCoordinate;\n" +             "uniform samplerExternalOES inputImageTexture;\n" +             "\n" +             "void main()\n" +             "{\n" +             "    vec4 nColor=texture2D(inputImageTexture, textureCoordinate);\n"+             "    if (log(nColor.g / (pow(nColor.b, 0.391) * pow(nColor.r, 0.609))) < -0.4)\n"+             "    {\n"+             "         gl_FragColor = vec4(1.0, 1.0, 1.0, nColor.a);\n"+             "    }\n"+             "    else\n"+             "    {\n" +             "         gl_FragColor = nColor;\n"+             "    }\n"+             "}";

2.计算高斯模糊 precision mediump float;

//在片元着色器这里添加这个 sampler2D 表示我们要添加2D贴图 uniform sampler2D u_TextureUnit;

varying vec2 v_TextureCoordinates;

void main(){     vec4 color = vec4(0.0);     int coreSize=3;     int halfSize=coreSize/2;     float texelOffset = 0.01;     //创建我们计算好的卷积核     float kernel[9];     kernel[6] = 1.0; kernel[7] = 2.0; kernel[8] = 1.0;     kernel[3] = 2.0; kernel[4] = 4.0; kernel[5] = 2.0;     kernel[0] = 1.0; kernel[1] = 2.0; kernel[2] = 1.0;     int index = 0;     //每一块都进行图像卷积。     for(int y=0;y