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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
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.
GPUImagePrewittEdgeDetectionFilter 属于 GPUImage 图像视觉效果相关,用于图像普瑞维特(Prewitt)边缘检测。shader 源码如下:
/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES GPUImage GPUImagePrewittEdgeDetectionFilter
//@Time:2022/07/02 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 kGPUImagePrewittFragmentShaderString = SHADER_STRING
(
precision highp 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 sampler2D inputImageTexture;
uniform float edgeStrength;
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 - topIntensity - topRightIntensity + bottomLeftIntensity + bottomIntensity + bottomRightIntensity;
float v = -bottomLeftIntensity - leftIntensity - topLeftIntensity + bottomRightIntensity + rightIntensity + topRightIntensity;
float mag = length(vec2(h, v)) * edgeStrength;
gl_FragColor = vec4(vec3(mag), 1.0);
}
);
#else
NSString *const kGPUImagePrewittFragmentShaderString = 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 sampler2D inputImageTexture;
uniform float edgeStrength;
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 - topIntensity - topRightIntensity + bottomLeftIntensity + bottomIntensity + bottomRightIntensity;
float v = -bottomLeftIntensity - leftIntensity - topLeftIntensity + bottomRightIntensity + rightIntensity + topRightIntensity;
float mag = length(vec2(h, v)) * edgeStrength;
gl_FragColor = vec4(vec3(mag), 1.0);
}
);
#endif
使用GPUImagePrewittEdgeDetectionFilter **,**原图如下:
使用GPUImagePrewittEdgeDetectionFilter 效果如下:
OpenGL ES Demo 下载地址 : IOS OpenGL ES GPUImage 图像普瑞维特(Prewitt)边缘检测 GPUImagePrewittEdgeDetectionFilter
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