模仿Flickr 使用GPUImage的实时相机滤镜(iOS源代码)

from: http://code1.okbase.net/codefile/GPUImagePoissonBlendFilter.m_2016011433675_220.htm
#import "GPUImagePoissonBlendFilter.h"

#if
TARGET_IPHONE_SIMULATOR ||
TARGET_OS_IPHONE

NSString
*const kGPUImagePoissonBlendFragmentShaderString
= SHADER_STRING

(

precision mediump
float;

varying vec2 textureCoordinate;

varying vec2 leftTextureCoordinate;

varying vec2 rightTextureCoordinate;

varying vec2 topTextureCoordinate;

varying vec2 bottomTextureCoordinate;

varying vec2 textureCoordinate2;

varying vec2 leftTextureCoordinate2;

varying vec2 rightTextureCoordinate2;

varying vec2 topTextureCoordinate2;

varying vec2 bottomTextureCoordinate2;

uniform sampler2D inputImageTexture;

uniform sampler2D inputImageTexture2;

uniform lowp float mixturePercent;

void
main()

{

vec4 centerColor
= texture2D(inputImageTexture, textureCoordinate);

vec3 bottomColor
= texture2D(inputImageTexture, bottomTextureCoordinate).rgb;

vec3 leftColor
= texture2D(inputImageTexture, leftTextureCoordinate).rgb;

vec3 rightColor
= texture2D(inputImageTexture, rightTextureCoordinate).rgb;

vec3 topColor
= texture2D(inputImageTexture, topTextureCoordinate).rgb;

vec4 centerColor2
= texture2D(inputImageTexture2, textureCoordinate2);

vec3 bottomColor2
= texture2D(inputImageTexture2, bottomTextureCoordinate2).rgb;

vec3 leftColor2
= texture2D(inputImageTexture2, leftTextureCoordinate2).rgb;

vec3 rightColor2
= texture2D(inputImageTexture2, rightTextureCoordinate2).rgb;

vec3 topColor2
= texture2D(inputImageTexture2, topTextureCoordinate2).rgb;

vec3 meanColor
= (bottomColor + leftColor
+ rightColor + topColor)
/ 4.0;

vec3 diffColor
= centerColor.rgb - meanColor;

vec3 meanColor2
= (bottomColor2 + leftColor2
+ rightColor2 + topColor2)
/ 4.0;

vec3 diffColor2
= centerColor2.rgb - meanColor2;

vec3 gradColor
= (meanColor + diffColor2);

gl_FragColor
= vec4(mix(centerColor.rgb, gradColor, centerColor2.a
* mixturePercent), centerColor.a);

}

);

#else

NSString
*const kGPUImagePoissonBlendFragmentShaderString
= SHADER_STRING

(

varying vec2 textureCoordinate;

varying vec2 leftTextureCoordinate;

varying vec2 rightTextureCoordinate;

varying vec2 topTextureCoordinate;

varying vec2 bottomTextureCoordinate;

varying vec2 textureCoordinate2;

varying vec2 leftTextureCoordinate2;

varying vec2 rightTextureCoordinate2;

varying vec2 topTextureCoordinate2;

varying vec2 bottomTextureCoordinate2;

uniform sampler2D inputImageTexture;

uniform sampler2D inputImageTexture2;

uniform float mixturePercent;

void
main()

{

vec4 centerColor
= texture2D(inputImageTexture, textureCoordinate);

vec3 bottomColor
= texture2D(inputImageTexture, bottomTextureCoordinate).rgb;

vec3 leftColor
= texture2D(inputImageTexture, leftTextureCoordinate).rgb;

vec3 rightColor
= texture2D(inputImageTexture, rightTextureCoordinate).rgb;

vec3 topColor
= texture2D(inputImageTexture, topTextureCoordinate).rgb;

vec4 centerColor2
= texture2D(inputImageTexture2, textureCoordinate2);

vec3 bottomColor2
= texture2D(inputImageTexture2, bottomTextureCoordinate2).rgb;

vec3 leftColor2
= texture2D(inputImageTexture2, leftTextureCoordinate2).rgb;

vec3 rightColor2
= texture2D(inputImageTexture2, rightTextureCoordinate2).rgb;

vec3 topColor2
= texture2D(inputImageTexture2, topTextureCoordinate2).rgb;

vec3 meanColor
= (bottomColor + leftColor
+ rightColor + topColor)
/ 4.0;

vec3 diffColor
= centerColor.rgb - meanColor;

vec3 meanColor2
= (bottomColor2 + leftColor2
+ rightColor2 + topColor2)
/ 4.0;

vec3 diffColor2
= centerColor2.rgb - meanColor2;

vec3 gradColor
= (meanColor + diffColor2);

gl_FragColor
= vec4(mix(centerColor.rgb, gradColor, centerColor2.a
* mixturePercent), centerColor.a);

}

);

#endif

@implementation
GPUImagePoissonBlendFilter

@synthesize mix
= _mix;

@synthesize numIterations
= _numIterations;

- (id)init;

{

if (!(self
= [super initWithFragmentShaderFromString:kGPUImagePoissonBlendFragmentShaderString]))

{

return nil;

}

mixUniform
= [filterProgram uniformIndex:@"mixturePercent"];

self.mix
= 0.5;

self.numIterations
= 10;

return self;

}

- (void)setMix:(CGFloat)newValue;

{

_mix = newValue;

[self setFloat:_mix forUniform:mixUniform program:filterProgram];

}

//- (void)setOutputFBO;

//{

// if (self.numIterations % 2 == 1) {

// [self setSecondFilterFBO];

// } else {

// [self setFilterFBO];

// }

//}

- (void)renderToTextureWithVertices:(const
GLfloat *)vertices textureCoordinates:(const
GLfloat *)textureCoordinates;

{

// Run the first stage of the two-pass filter

[GPUImageContext setActiveShaderProgram:filterProgram];

[super renderToTextureWithVertices:vertices textureCoordinates:textureCoordinates];

for (int pass
= 1; pass
< self.numIterations; pass++) {

if (pass
% 2
== 0) {

[GPUImageContext setActiveShaderProgram:filterProgram];

// TODO: This will over-unlock the incoming framebuffer

[super renderToTextureWithVertices:vertices textureCoordinates:[[self
class] textureCoordinatesForRotation:kGPUImageNoRotation]];

} else {

// Run the second stage of the two-pass filter

secondOutputFramebuffer
= [[GPUImageContext sharedFramebufferCache] fetchFramebufferForSize:[self sizeOfFBO] textureOptions:self.outputTextureOptions onlyTexture:NO];

[secondOutputFramebuffer activateFramebuffer];

[GPUImageContext setActiveShaderProgram:filterProgram];

glClearColor(backgroundColorRed, backgroundColorGreen, backgroundColorBlue, backgroundColorAlpha);

glClear(GL_COLOR_BUFFER_BIT);

glActiveTexture(GL_TEXTURE2);

glBindTexture(GL_TEXTURE_2D, [outputFramebuffer texture]);

glUniform1i(filterInputTextureUniform,
2);

glActiveTexture(GL_TEXTURE3);

glBindTexture(GL_TEXTURE_2D, [secondInputFramebuffer texture]);

glUniform1i(filterInputTextureUniform2,
3);

glVertexAttribPointer(filterPositionAttribute,
2, GL_FLOAT,
0, 0, vertices);

glVertexAttribPointer(filterTextureCoordinateAttribute,
2, GL_FLOAT,
0, 0, [[self class] textureCoordinatesForRotation:kGPUImageNoRotation]);

glVertexAttribPointer(filterSecondTextureCoordinateAttribute,
2, GL_FLOAT,
0, 0, [[self class] textureCoordinatesForRotation:inputRotation2]);

glDrawArrays(GL_TRIANGLE_STRIP,
0, 4);

}

}

}

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