IOS – OpenGL ES 同心圆像素化马赛克效果 GPUImagePolarPixel

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 同心圆像素化马赛克效果 GPUImagePolarPixel
//@Time:2022/05/23 06:30
//@Motto:不积跬步无以至千里，不积小流无以成江海，程序人生的精彩需要坚持不懈地积累！
/******************************************************************************************/

#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
NSString *const kGPUImagePixellationFragmentShaderString = SHADER_STRING
(
 varying highp vec2 textureCoordinate;

 uniform sampler2D inputImageTexture;

 uniform highp float fractionalWidthOfPixel;
 uniform highp float aspectRatio;

 void main()
 {
     highp vec2 sampleDivisor = vec2(fractionalWidthOfPixel, fractionalWidthOfPixel / aspectRatio);

     highp vec2 samplePos = textureCoordinate - mod(textureCoordinate, sampleDivisor) + 0.5 * sampleDivisor;
     gl_FragColor = texture2D(inputImageTexture, samplePos );
 }
);
#else
NSString *const kGPUImagePixellationFragmentShaderString = SHADER_STRING
(
 varying vec2 textureCoordinate;

 uniform sampler2D inputImageTexture;

 uniform float fractionalWidthOfPixel;
 uniform float aspectRatio;

 void main()
 {
     vec2 sampleDivisor = vec2(fractionalWidthOfPixel, fractionalWidthOfPixel / aspectRatio);

     vec2 samplePos = textureCoordinate - mod(textureCoordinate, sampleDivisor) + 0.5 * sampleDivisor;
     gl_FragColor = texture2D(inputImageTexture, samplePos );
 }
);
#endif