IOS – OpenGL ES 设置图像模糊 GPUImageFastBlurFilter-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.

GPUImageFastBlurFilter 属于 GPUImage 图像处理相关，用来图像模糊，shader 源码如下：

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 设置图像模糊 GPUImageFastBlurFilter
//@Time:2022/04/22 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！
/******************************************************************************************/

attribute vec4 position;
attribute vec2 inputTextureCoordinate;
uniform highp float texelWidthOffset;
uniform highp float texelHeightOffset;
uniform highp float blurSize;
varying highp vec2 centerTextureCoordinate;
varying highp vec2 oneStepLeftTextureCoordinate;
varying highp vec2 twoStepsLeftTextureCoordinate;
varying highp vec2 oneStepRightTextureCoordinate;
varying highp vec2 twoStepsRightTextureCoordinate;
// const float offset[3] = float[]( 0.0, 1.3846153846, 3.2307692308 );
void main()
{
    gl_Position = position;
    vec2 firstOffset = vec2(1.3846153846 * texelWidthOffset, 1.3846153846 * texelHeightOffset) * blurSize;
    vec2 secondOffset = vec2(3.2307692308 * texelWidthOffset, 3.2307692308 * texelHeightOffset) * blurSize;
    centerTextureCoordinate = inputTextureCoordinate;
    oneStepLeftTextureCoordinate = inputTextureCoordinate - firstOffset;
    twoStepsLeftTextureCoordinate = inputTextureCoordinate - secondOffset;
    oneStepRightTextureCoordinate = inputTextureCoordinate + firstOffset;
    twoStepsRightTextureCoordinate = inputTextureCoordinate + secondOffset;
}




precision highp float;
uniform sampler2D inputImageTexture;
varying highp vec2 centerTextureCoordinate;
varying highp vec2 oneStepLeftTextureCoordinate;
varying highp vec2 twoStepsLeftTextureCoordinate;
n varying highp vec2 oneStepRightTextureCoordinate;
varying highp vec2 twoStepsRightTextureCoordinate;
// const float weight[3] = float[]( 0.2270270270, 0.3162162162, 0.0702702703 );
void main()
{
    lowp vec4 fragmentColor = texture2D(inputImageTexture, centerTextureCoordinate) * 0.2270270270;
    fragmentColor += texture2D(inputImageTexture, oneStepLeftTextureCoordinate) * 0.3162162162;
    fragmentColor += texture2D(inputImageTexture, oneStepRightTextureCoordinate) * 0.3162162162;
    fragmentColor += texture2D(inputImageTexture, twoStepsLeftTextureCoordinate) * 0.0702702703;
    fragmentColor += texture2D(inputImageTexture, twoStepsRightTextureCoordinate) * 0.0702702703;
    gl_FragColor = fragmentColor;
}