#import "GPUImageWhiteBalanceFilter.h"
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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NSString *const kGPUImageWhiteBalanceFragmentShaderString = SHADER_STRING
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(
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uniform sampler2D inputImageTexture;
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varying highp vec2 textureCoordinate;
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uniform lowp float temperature;
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uniform lowp float tint;
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const lowp vec3 warmFilter = vec3(0.93, 0.54, 0.0);
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const mediump mat3 RGBtoYIQ = mat3(0.299, 0.587, 0.114, 0.596, -0.274, -0.322, 0.212, -0.523, 0.311);
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const mediump mat3 YIQtoRGB = mat3(1.0, 0.956, 0.621, 1.0, -0.272, -0.647, 1.0, -1.105, 1.702);
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void main()
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{
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lowp vec4 source = texture2D(inputImageTexture, textureCoordinate);
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mediump vec3 yiq = RGBtoYIQ * source.rgb; //adjusting tint
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yiq.b = clamp(yiq.b + tint*0.5226*0.1, -0.5226, 0.5226);
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lowp vec3 rgb = YIQtoRGB * yiq;
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lowp vec3 processed = vec3(
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(rgb.r < 0.5 ? (2.0 * rgb.r * warmFilter.r) : (1.0 - 2.0 * (1.0 - rgb.r) * (1.0 - warmFilter.r))), //adjusting temperature
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(rgb.g < 0.5 ? (2.0 * rgb.g * warmFilter.g) : (1.0 - 2.0 * (1.0 - rgb.g) * (1.0 - warmFilter.g))),
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(rgb.b < 0.5 ? (2.0 * rgb.b * warmFilter.b) : (1.0 - 2.0 * (1.0 - rgb.b) * (1.0 - warmFilter.b))));
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gl_FragColor = vec4(mix(rgb, processed, temperature), source.a);
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}
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);
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#else
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NSString *const kGPUImageWhiteBalanceFragmentShaderString = SHADER_STRING
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(
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uniform sampler2D inputImageTexture;
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varying vec2 textureCoordinate;
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uniform float temperature;
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uniform float tint;
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const vec3 warmFilter = vec3(0.93, 0.54, 0.0);
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const mat3 RGBtoYIQ = mat3(0.299, 0.587, 0.114, 0.596, -0.274, -0.322, 0.212, -0.523, 0.311);
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const mat3 YIQtoRGB = mat3(1.0, 0.956, 0.621, 1.0, -0.272, -0.647, 1.0, -1.105, 1.702);
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void main()
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{
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vec4 source = texture2D(inputImageTexture, textureCoordinate);
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vec3 yiq = RGBtoYIQ * source.rgb; //adjusting tint
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yiq.b = clamp(yiq.b + tint*0.5226*0.1, -0.5226, 0.5226);
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vec3 rgb = YIQtoRGB * yiq;
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vec3 processed = vec3(
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(rgb.r < 0.5 ? (2.0 * rgb.r * warmFilter.r) : (1.0 - 2.0 * (1.0 - rgb.r) * (1.0 - warmFilter.r))), //adjusting temperature
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(rgb.g < 0.5 ? (2.0 * rgb.g * warmFilter.g) : (1.0 - 2.0 * (1.0 - rgb.g) * (1.0 - warmFilter.g))),
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(rgb.b < 0.5 ? (2.0 * rgb.b * warmFilter.b) : (1.0 - 2.0 * (1.0 - rgb.b) * (1.0 - warmFilter.b))));
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gl_FragColor = vec4(mix(rgb, processed, temperature), source.a);
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}
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);
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#endif
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@implementation GPUImageWhiteBalanceFilter
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@synthesize temperature = _temperature;
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@synthesize tint = _tint;
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#pragma mark -
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#pragma mark Initialization and teardown
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- (id)init;
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{
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if (!(self = [super initWithFragmentShaderFromString:kGPUImageWhiteBalanceFragmentShaderString]))
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{
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return nil;
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}
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temperatureUniform = [filterProgram uniformIndex:@"temperature"];
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tintUniform = [filterProgram uniformIndex:@"tint"];
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self.temperature = 5000.0;
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self.tint = 0.0;
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return self;
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}
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#pragma mark -
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#pragma mark Accessors
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- (void)setTemperature:(CGFloat)newValue;
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{
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_temperature = newValue;
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[self setFloat:_temperature < 5000 ? 0.0004 * (_temperature-5000.0) : 0.00006 * (_temperature-5000.0) forUniform:temperatureUniform program:filterProgram];
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}
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- (void)setTint:(CGFloat)newValue;
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{
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_tint = newValue;
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[self setFloat:_tint / 100.0 forUniform:tintUniform program:filterProgram];
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}
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@end
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