IOS – OpenGL ES 图像晕影扩散 GPUImageVignetteFilter

原创

猿说编程[Python和C]

发布于 2023-04-01 08:16:31

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发布于 2023-04-01 08:16:31

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.

GPUImageVignetteFilter 属于 GPUImage 图像视觉效果相关，用来处理图片晕影扩散。shader 源码如下：

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 图像晕影扩散 GPUImageVignetteFilter
//@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 kGPUImageVignetteFragmentShaderString = SHADER_STRING
(
 uniform sampler2D inputImageTexture;
 varying highp vec2 textureCoordinate;

 uniform lowp vec2 vignetteCenter;
 uniform lowp vec3 vignetteColor;
 uniform highp float vignetteStart;
 uniform highp float vignetteEnd;

 void main()
 {
     lowp vec4 sourceImageColor = texture2D(inputImageTexture, textureCoordinate);
     lowp float d = distance(textureCoordinate, vec2(vignetteCenter.x, vignetteCenter.y));
     lowp float percent = smoothstep(vignetteStart, vignetteEnd, d);
     gl_FragColor = vec4(mix(sourceImageColor.rgb, vignetteColor, percent), sourceImageColor.a);
 }
);
#else
NSString *const kGPUImageVignetteFragmentShaderString = SHADER_STRING
(
 uniform sampler2D inputImageTexture;
 varying vec2 textureCoordinate;

 uniform vec2 vignetteCenter;
 uniform vec3 vignetteColor;
 uniform float vignetteStart;
 uniform float vignetteEnd;

 void main()
 {
     vec4 sourceImageColor = texture2D(inputImageTexture, textureCoordinate);
     float d = distance(textureCoordinate, vec2(vignetteCenter.x, vignetteCenter.y));
     float percent = smoothstep(vignetteStart, vignetteEnd, d);
     gl_FragColor = vec4(mix(sourceImageColor.rgb, vignetteColor, percent), sourceImageColor.a);
 }
);
#endif