attribute vec4 position; //输入顶点位置属性attribute vec4 inputTextureCoordinate;//输入纹理位置属性varying vec2 textureCoordinate;//输出给片段着色器的纹理位置void main(){gl_Position = position;//输出给片段着色器的顶点位置textureCoordinate = inputTextureCoordinate.xy;//告诉片段着色器，顶点着色器正在处理的像素点。}

 varying highp vec2 textureCoordinate;uniform sampler2D inputImageTexture;//输入的纹理图片。也就是我们要处理的图片uniform lowp float brightness;//亮度值，我们在程序中可以调整的。void main(){lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);//输入图片的纹理颜色gl_FragColor = vec4((textureColor.rgb + vec3(brightness)), textureColor.w);//像素着色颜色。将每个像素的RGB分量与亮度值相加，得到心的像素颜色。即算法实现}

GPUImageBrightnessFilter *filter = [[GPUImageBrightnessFilter alloc] init];

filter.brightness = value;

[filter forceProcessingAtSize:image.size];

GPUImagePicture *pic = [[GPUImagePicture alloc] initWithImage:image];
[pic addTarget:filter];

[pic processImage];[filter useNextFrameForImageCapture];

return [filter imageFromCurrentFramebuffer];

+ (UIImage *)changeValueForBrightnessFilter:(float)value image:(UIImage *)image;
{GPUImageBrightnessFilter *filter = [[GPUImageBrightnessFilter alloc] init];filter.brightness = value;[filter forceProcessingAtSize:image.size];GPUImagePicture *pic = [[GPUImagePicture alloc] initWithImage:image];[pic addTarget:filter];[pic processImage];[filter useNextFrameForImageCapture];return [filter imageFromCurrentFramebuffer];
}

- (id)init;
{if (!(self = [super initWithFragmentShaderFromString:kGPUImageBrightnessFragmentShaderString])){return nil;}brightnessUniform = [filterProgram uniformIndex:@"brightness"];self.brightness = 0.0;return self;
}

- (void)setBrightness:(CGFloat)newValue;
{_brightness = newValue;[self setFloat:_brightness forUniform:brightnessUniform program:filterProgram];
}