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#import "GPUImageChromaKeyBlendFilter.h"
// Shader code based on Apple's CIChromaKeyFilter example: https://developer.apple.com/library/mac/#samplecode/CIChromaKeyFilter/Introduction/Intro.html
#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
NSString *const kGPUImageChromaKeyBlendFragmentShaderString = SHADER_STRING
(
precision highp float;
varying highp vec2 textureCoordinate;
varying highp vec2 textureCoordinate2;
uniform float thresholdSensitivity;
uniform float smoothing;
uniform vec3 colorToReplace;
uniform sampler2D inputImageTexture;
uniform sampler2D inputImageTexture2;
void main()
{
vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
vec4 textureColor2 = texture2D(inputImageTexture2, textureCoordinate2);
float maskY = 0.2989 * colorToReplace.r + 0.5866 * colorToReplace.g + 0.1145 * colorToReplace.b;
float maskCr = 0.7132 * (colorToReplace.r - maskY);
float maskCb = 0.5647 * (colorToReplace.b - maskY);
float Y = 0.2989 * textureColor.r + 0.5866 * textureColor.g + 0.1145 * textureColor.b;
float Cr = 0.7132 * (textureColor.r - Y);
float Cb = 0.5647 * (textureColor.b - Y);
// float blendValue = 1.0 - smoothstep(thresholdSensitivity - smoothing, thresholdSensitivity , abs(Cr - maskCr) + abs(Cb - maskCb));
float blendValue = 1.0 - smoothstep(thresholdSensitivity, thresholdSensitivity + smoothing, distance(vec2(Cr, Cb), vec2(maskCr, maskCb)));
gl_FragColor = mix(textureColor, textureColor2, blendValue);
}
);
#else
NSString *const kGPUImageChromaKeyBlendFragmentShaderString = SHADER_STRING
(
varying vec2 textureCoordinate;
varying vec2 textureCoordinate2;
uniform float thresholdSensitivity;
uniform float smoothing;
uniform vec3 colorToReplace;
uniform sampler2D inputImageTexture;
uniform sampler2D inputImageTexture2;
void main()
{
vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
vec4 textureColor2 = texture2D(inputImageTexture2, textureCoordinate2);
float maskY = 0.2989 * colorToReplace.r + 0.5866 * colorToReplace.g + 0.1145 * colorToReplace.b;
float maskCr = 0.7132 * (colorToReplace.r - maskY);
float maskCb = 0.5647 * (colorToReplace.b - maskY);
float Y = 0.2989 * textureColor.r + 0.5866 * textureColor.g + 0.1145 * textureColor.b;
float Cr = 0.7132 * (textureColor.r - Y);
float Cb = 0.5647 * (textureColor.b - Y);
// float blendValue = 1.0 - smoothstep(thresholdSensitivity - smoothing, thresholdSensitivity , abs(Cr - maskCr) + abs(Cb - maskCb));
float blendValue = 1.0 - smoothstep(thresholdSensitivity, thresholdSensitivity + smoothing, distance(vec2(Cr, Cb), vec2(maskCr, maskCb)));
gl_FragColor = mix(textureColor, textureColor2, blendValue);
}
);
#endif
@implementation GPUImageChromaKeyBlendFilter
@synthesize thresholdSensitivity = _thresholdSensitivity;
@synthesize smoothing = _smoothing;
- (id)init;
{
if (!(self = [super initWithFragmentShaderFromString:kGPUImageChromaKeyBlendFragmentShaderString]))
{
return nil;
}
thresholdSensitivityUniform = [filterProgram uniformIndex:@"thresholdSensitivity"];
smoothingUniform = [filterProgram uniformIndex:@"smoothing"];
colorToReplaceUniform = [filterProgram uniformIndex:@"colorToReplace"];
self.thresholdSensitivity = 0.4;
self.smoothing = 0.1;
[self setColorToReplaceRed:0.0 green:1.0 blue:0.0];
return self;
}
#pragma mark -
#pragma mark Accessors
- (void)setColorToReplaceRed:(GLfloat)redComponent green:(GLfloat)greenComponent blue:(GLfloat)blueComponent;
{
GPUVector3 colorToReplace = {redComponent, greenComponent, blueComponent};
[self setVec3:colorToReplace forUniform:colorToReplaceUniform program:filterProgram];
}
- (void)setThresholdSensitivity:(CGFloat)newValue;
{
_thresholdSensitivity = newValue;
[self setFloat:(GLfloat)_thresholdSensitivity forUniform:thresholdSensitivityUniform program:filterProgram];
}
- (void)setSmoothing:(CGFloat)newValue;
{
_smoothing = newValue;
[self setFloat:(GLfloat)_smoothing forUniform:smoothingUniform program:filterProgram];
}
@end