IOS – OpenGL ES 图像哈哈镜效果 GPUImageStretchDistortionFilter

原创

猿说编程[Python和C]

发布于 2023-04-01 08:23:07

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发布于 2023-04-01 08:23:07

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.

GPUImageStretchDistortionFilter 属于 GPUImage 图像视觉效果相关，用来处理图像哈哈镜。shader 源码如下：

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 图像哈哈镜效果 GPUImageStretchDistortionFilter
//@Time:2022/06/02 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 kGPUImageStretchDistortionFragmentShaderString = SHADER_STRING
(
 varying highp vec2 textureCoordinate;

 uniform sampler2D inputImageTexture;

 uniform highp vec2 center;

 void main()
 {
     highp vec2 normCoord = 2.0 * textureCoordinate - 1.0;
     highp vec2 normCenter = 2.0 * center - 1.0;

     normCoord -= normCenter;
     mediump vec2 s = sign(normCoord);
     normCoord = abs(normCoord);
     normCoord = 0.5 * normCoord + 0.5 * smoothstep(0.25, 0.5, normCoord) * normCoord;
     normCoord = s * normCoord;

     normCoord += normCenter;

     mediump vec2 textureCoordinateToUse = normCoord / 2.0 + 0.5;


     gl_FragColor = texture2D(inputImageTexture, textureCoordinateToUse );

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

 uniform sampler2D inputImageTexture;

 uniform vec2 center;

 void main()
 {
     vec2 normCoord = 2.0 * textureCoordinate - 1.0;
     vec2 normCenter = 2.0 * center - 1.0;

     normCoord -= normCenter;
     vec2 s = sign(normCoord);
     normCoord = abs(normCoord);
     normCoord = 0.5 * normCoord + 0.5 * smoothstep(0.25, 0.5, normCoord) * normCoord;
     normCoord = s * normCoord;

     normCoord += normCenter;

     vec2 textureCoordinateToUse = normCoord / 2.0 + 0.5;

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