IOS – OpenGL ES 图像素描 GPUImageSketchFilter

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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.

GPUImageSketchFilter 属于 GPUImage 图像视觉效果相关，用来处理图片素描。shader 源码如下：

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 图像素描 GPUImageSketchFilter
//@Time:2022/04/14 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 kGPUImageSketchFragmentShaderString = SHADER_STRING
(
 precision mediump float;
 
 varying vec2 textureCoordinate;
 varying vec2 leftTextureCoordinate;
 varying vec2 rightTextureCoordinate;
 
 varying vec2 topTextureCoordinate;
 varying vec2 topLeftTextureCoordinate;
 varying vec2 topRightTextureCoordinate;
 
 varying vec2 bottomTextureCoordinate;
 varying vec2 bottomLeftTextureCoordinate;
 varying vec2 bottomRightTextureCoordinate;
 
 uniform float edgeStrength;

 uniform sampler2D inputImageTexture;
 
 void main()
 {
     float bottomLeftIntensity = texture2D(inputImageTexture, bottomLeftTextureCoordinate).r;
     float topRightIntensity = texture2D(inputImageTexture, topRightTextureCoordinate).r;
     float topLeftIntensity = texture2D(inputImageTexture, topLeftTextureCoordinate).r;
     float bottomRightIntensity = texture2D(inputImageTexture, bottomRightTextureCoordinate).r;
     float leftIntensity = texture2D(inputImageTexture, leftTextureCoordinate).r;
     float rightIntensity = texture2D(inputImageTexture, rightTextureCoordinate).r;
     float bottomIntensity = texture2D(inputImageTexture, bottomTextureCoordinate).r;
     float topIntensity = texture2D(inputImageTexture, topTextureCoordinate).r;
     float h = -topLeftIntensity - 2.0 * topIntensity - topRightIntensity + bottomLeftIntensity + 2.0 * bottomIntensity + bottomRightIntensity;
     float v = -bottomLeftIntensity - 2.0 * leftIntensity - topLeftIntensity + bottomRightIntensity + 2.0 * rightIntensity + topRightIntensity;
     
     float mag = 1.0 - (length(vec2(h, v)) * edgeStrength);
     
     gl_FragColor = vec4(vec3(mag), 1.0);
 }
);
#else
NSString *const kGPUImageSketchFragmentShaderString = SHADER_STRING
(
 varying vec2 textureCoordinate;
 varying vec2 leftTextureCoordinate;
 varying vec2 rightTextureCoordinate;
 
 varying vec2 topTextureCoordinate;
 varying vec2 topLeftTextureCoordinate;
 varying vec2 topRightTextureCoordinate;
 
 varying vec2 bottomTextureCoordinate;
 varying vec2 bottomLeftTextureCoordinate;
 varying vec2 bottomRightTextureCoordinate;
 
 uniform float edgeStrength;

 uniform sampler2D inputImageTexture;
 
 void main()
 {
     float bottomLeftIntensity = texture2D(inputImageTexture, bottomLeftTextureCoordinate).r;
     float topRightIntensity = texture2D(inputImageTexture, topRightTextureCoordinate).r;
     float topLeftIntensity = texture2D(inputImageTexture, topLeftTextureCoordinate).r;
     float bottomRightIntensity = texture2D(inputImageTexture, bottomRightTextureCoordinate).r;
     float leftIntensity = texture2D(inputImageTexture, leftTextureCoordinate).r;
     float rightIntensity = texture2D(inputImageTexture, rightTextureCoordinate).r;
     float bottomIntensity = texture2D(inputImageTexture, bottomTextureCoordinate).r;
     float topIntensity = texture2D(inputImageTexture, topTextureCoordinate).r;
     float h = -topLeftIntensity - 2.0 * topIntensity - topRightIntensity + bottomLeftIntensity + 2.0 * bottomIntensity + bottomRightIntensity;
     float v = -bottomLeftIntensity - 2.0 * leftIntensity - topLeftIntensity + bottomRightIntensity + 2.0 * rightIntensity + topRightIntensity;
     
     float mag = 1.0 - (length(vec2(h, v)) * edgeStrength);
     
     gl_FragColor = vec4(vec3(mag), 1.0);
 }
);
#endif

二.效果演示

使用GPUImageSketchFilter 裁剪来完成图片素描效果，原图：

GPUImageSketchFilter 效果图：

三.源码下载

OpenGL ES Demo 下载地址 : IOS – OpenGL ES 设置图像滤镜 GPUImageSketchFilter

四.猜你喜欢

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13. GPUImage – 色彩直方图 GPUImageHistogramFilter
14. GPUImage – 色彩直方图 GPUImageHistogramGenerator
15. GPUImage – 像素平均色值 GPUImageAverageColor
16. GPUImage – 亮度平均 GPUImageLuminosity
17. IOS – OpenGL ES 调节图像色度 GPUImageHueFilter
18. IOS – OpenGL ES 指定颜色抠图 GPUImageChromaKeyFilter
19. IOS – OpenGL ES 调节图像白平衡/色温 GPUImageWhiteBalanceFilter
20. IOS – OpenGL ES 设置图像 lookup 滤镜 GPUImageLookupFilter
21. IOS – OpenGL ES 设置图像滤镜 GPUImageAmatorkaFilter
22. IOS – OpenGL ES 设置图像滤镜 GPUImageSoftEleganceFilter
23. IOS – OpenGL ES 设置图像滤镜 GPUImageLineGenerator
24. IOS – OpenGL ES 设置图像滤镜 GPUImageTransformFilter
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26. IOS – OpenGL ES 图像素描 GPUImageSketchFilter