IOS – OpenGL ES 图像鱼眼扩散效果 GPUImageBulgeDistortionFilter

原创

猿说编程[Python和C]

发布于 2023-04-01 08:18:10

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发布于 2023-04-01 08:18:10

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.

GPUImageBulgeDistortionFilter 属于 GPUImage 图像视觉效果相关，用来处理图像鱼眼扩散效果。shader 源码如下：

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 图像鱼眼扩散效果 GPUImageBulgeDistortionFilter
//@Time:2022/05/30 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 kGPUImageBulgeDistortionFragmentShaderString = 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 - center.y) * aspectRatio) + center.y);
    highp float dist = distance(center, textureCoordinateToUse);
    textureCoordinateToUse = textureCoordinate;

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

        textureCoordinateToUse = textureCoordinateToUse * percent;
        textureCoordinateToUse += center;
    }

    gl_FragColor = texture2D(inputImageTexture, textureCoordinateToUse );
 }
);
#else
NSString *const kGPUImageBulgeDistortionFragmentShaderString = 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 - center.y) * aspectRatio) + center.y);
    float dist = distance(center, textureCoordinateToUse);
    textureCoordinateToUse = textureCoordinate;

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

        textureCoordinateToUse = textureCoordinateToUse * percent;
        textureCoordinateToUse += center;
    }

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