IOS – OpenGL ES 图像凹面镜放大效果 GPUImagePinchDistortionFilter

原创

猿说编程[Python和C]

发布于 2023-04-01 00:22:21

43200

代码可运行

文章被收录于专栏：猿说编程猿说编程

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代码可运行

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.

GPUImagePinchDistortionFilter 属于 GPUImage 图像视觉效果相关，用来处理图像凹面镜放大。shader 源码如下：

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 图像凹面镜效果 GPUImagePinchDistortionFilter
//@Time:2022/06/01 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！
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
NSString *const kGPUImagePinchDistortionFragmentShaderString = SHADER_STRING
(
 varying highp vec2 textureCoordinate;

 uniform sampler2D inputImageTexture;

 uniform highp float aspectRatio;
 uniform highp vec2 center;
 uniform highp float radius;
 uniform highp float scale;

 void main()
 {
     highp vec2 textureCoordinateToUse = vec2(textureCoordinate.x, (textureCoordinate.y * aspectRatio + 0.5 - 0.5 * aspectRatio));
     highp float dist = distance(center, textureCoordinateToUse);
     textureCoordinateToUse = textureCoordinate;

     if (dist < radius)
     {
         textureCoordinateToUse -= center;
         highp float percent = 1.0 + ((0.5 - dist) / 0.5) * scale;
         textureCoordinateToUse = textureCoordinateToUse * percent;
         textureCoordinateToUse += center;

         gl_FragColor = texture2D(inputImageTexture, textureCoordinateToUse );
     }
     else
     {
         gl_FragColor = texture2D(inputImageTexture, textureCoordinate );
     }
 }
);
#else
NSString *const kGPUImagePinchDistortionFragmentShaderString = SHADER_STRING
(
 varying vec2 textureCoordinate;

 uniform sampler2D inputImageTexture;

 uniform float aspectRatio;
 uniform vec2 center;
 uniform float radius;
 uniform float scale;

 void main()
 {
     vec2 textureCoordinateToUse = vec2(textureCoordinate.x, (textureCoordinate.y * aspectRatio + 0.5 - 0.5 * aspectRatio));
     float dist = distance(center, textureCoordinateToUse);
     textureCoordinateToUse = textureCoordinate;

     if (dist < radius)
     {
         textureCoordinateToUse -= center;
         float percent = 1.0 + ((0.5 - dist) / 0.5) * scale;
         textureCoordinateToUse = textureCoordinateToUse * percent;
         textureCoordinateToUse += center;

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