IOS – OpenGL ES 设置图像滤镜 GPUImageMissEtikateFilter-猿说编程

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零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES 基础

零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES 转场

零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES 特效

零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES 函数

零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES GPUImage 使用

零基础 OpenGL (ES) 学习路线推荐 : OpenGL (ES) 学习目录 >> OpenGL ES GLSL 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.

GPUImageMissEtikateFilter 属于 GPUImage 颜色处理相关，用来处理图片lookup 滤镜

GPUImageMissEtikateFilter 基于 Photoshop 行动的照片过滤器,类似 GPUImageLookupFilter；

shader 源码如下：

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 设置图像滤镜 GPUImageMissEtikateFilter
//@Time:2022/04/10 07:30
//@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 kGPUImageLookupFragmentShaderString = SHADER_STRING
(
 varying highp vec2 textureCoordinate;
 varying highp vec2 textureCoordinate2; // TODO: This is not used
 
 uniform sampler2D inputImageTexture;
 uniform sampler2D inputImageTexture2; // lookup texture
 
 uniform lowp float intensity;

 void main()
 {
     highp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
     
     highp float blueColor = textureColor.b * 63.0;
     
     highp vec2 quad1;
     quad1.y = floor(floor(blueColor) / 8.0);
     quad1.x = floor(blueColor) - (quad1.y * 8.0);
     
     highp vec2 quad2;
     quad2.y = floor(ceil(blueColor) / 8.0);
     quad2.x = ceil(blueColor) - (quad2.y * 8.0);
     
     highp vec2 texPos1;
     texPos1.x = (quad1.x * 0.125) + 0.5/512.0 + ((0.125 - 1.0/512.0) * textureColor.r);
     texPos1.y = (quad1.y * 0.125) + 0.5/512.0 + ((0.125 - 1.0/512.0) * textureColor.g);
     
     highp vec2 texPos2;
     texPos2.x = (quad2.x * 0.125) + 0.5/512.0 + ((0.125 - 1.0/512.0) * textureColor.r);
     texPos2.y = (quad2.y * 0.125) + 0.5/512.0 + ((0.125 - 1.0/512.0) * textureColor.g);
     
     lowp vec4 newColor1 = texture2D(inputImageTexture2, texPos1);
     lowp vec4 newColor2 = texture2D(inputImageTexture2, texPos2);
     
     lowp vec4 newColor = mix(newColor1, newColor2, fract(blueColor));
     gl_FragColor = mix(textureColor, vec4(newColor.rgb, textureColor.w), intensity);
 }
);
#else
NSString *const kGPUImageLookupFragmentShaderString = SHADER_STRING
(
 varying vec2 textureCoordinate;
 varying vec2 textureCoordinate2; // TODO: This is not used
 
 uniform sampler2D inputImageTexture;
 uniform sampler2D inputImageTexture2; // lookup texture
 
 uniform float intensity;
 
 void main()
 {
     vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
     
     float blueColor = textureColor.b * 63.0;
     
     vec2 quad1;
     quad1.y = floor(floor(blueColor) / 8.0);
     quad1.x = floor(blueColor) - (quad1.y * 8.0);
     
     vec2 quad2;
     quad2.y = floor(ceil(blueColor) / 8.0);
     quad2.x = ceil(blueColor) - (quad2.y * 8.0);
     
     vec2 texPos1;
     texPos1.x = (quad1.x * 0.125) + 0.5/512.0 + ((0.125 - 1.0/512.0) * textureColor.r);
     texPos1.y = (quad1.y * 0.125) + 0.5/512.0 + ((0.125 - 1.0/512.0) * textureColor.g);
     
     vec2 texPos2;
     texPos2.x = (quad2.x * 0.125) + 0.5/512.0 + ((0.125 - 1.0/512.0) * textureColor.r);
     texPos2.y = (quad2.y * 0.125) + 0.5/512.0 + ((0.125 - 1.0/512.0) * textureColor.g);
     
     vec4 newColor1 = texture2D(inputImageTexture2, texPos1);
     vec4 newColor2 = texture2D(inputImageTexture2, texPos2);
     
     vec4 newColor = mix(newColor1, newColor2, fract(blueColor));
     gl_FragColor = mix(textureColor, vec4(newColor.rgb, textureColor.w), intensity);
 }
);
#endif