IOS – OpenGL ES 图像漩涡 GPUImageSwirlFilter

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猿说编程[Python和C]

发布于 2023-04-01 08:17:29

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发布于 2023-04-01 08:17:29

文章被收录于专栏：猿说编程猿说编程

一.简介

GPUImage 共 125 个滤镜, 分为四类

1、Color adjustments : 31 filters , 颜色处理相关 2、Image processing : 40 filters , 图像处理相关. 3、Blending modes : 29 filters , 混合模式相关. 4、Visual effects : 25 filters , 视觉效果相关.

GPUImageSwirlFilter 属于 GPUImage 图像视觉效果相关，用来处理图片漩涡。shader 源码如下：

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 图像漩涡 GPUImageSwirlFilter
//@Time:2022/05/28 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 kGPUImageSwirlFragmentShaderString = SHADER_STRING
(
 varying highp vec2 textureCoordinate;

 uniform sampler2D inputImageTexture;

 uniform highp vec2 center;
 uniform highp float radius;
 uniform highp float angle;

 void main()
 {
     highp vec2 textureCoordinateToUse = textureCoordinate;
     highp float dist = distance(center, textureCoordinate);
     if (dist < radius)
     {
         textureCoordinateToUse -= center;
         highp float percent = (radius - dist) / radius;
         highp float theta = percent * percent * angle * 8.0;
         highp float s = sin(theta);
         highp float c = cos(theta);
         textureCoordinateToUse = vec2(dot(textureCoordinateToUse, vec2(c, -s)), dot(textureCoordinateToUse, vec2(s, c)));
         textureCoordinateToUse += center;
     }

     gl_FragColor = texture2D(inputImageTexture, textureCoordinateToUse );

 }
);
#else
NSString *const kGPUImageSwirlFragmentShaderString = SHADER_STRING
(
 varying vec2 textureCoordinate;

 uniform sampler2D inputImageTexture;

 uniform vec2 center;
 uniform float radius;
 uniform float angle;

 void main()
 {
     vec2 textureCoordinateToUse = textureCoordinate;
     float dist = distance(center, textureCoordinate);
     if (dist < radius)
     {
         textureCoordinateToUse -= center;
         float percent = (radius - dist) / radius;
         float theta = percent * percent * angle * 8.0;
         float s = sin(theta);
         float c = cos(theta);
         textureCoordinateToUse = vec2(dot(textureCoordinateToUse, vec2(c, -s)), dot(textureCoordinateToUse, vec2(s, c)));
         textureCoordinateToUse += center;
     }

     gl_FragColor = texture2D(inputImageTexture, textureCoordinateToUse );
 }
);
#endif