#import "GPUImageLuminanceThresholdFilter.h"
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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NSString *const kGPUImageLuminanceThresholdFragmentShaderString = SHADER_STRING
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(
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varying highp vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform highp float threshold;
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const highp vec3 W = vec3(0.2125, 0.7154, 0.0721);
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void main()
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{
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highp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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highp float luminance = dot(textureColor.rgb, W);
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highp float thresholdResult = step(threshold, luminance);
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gl_FragColor = vec4(vec3(thresholdResult), textureColor.w);
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}
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);
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#else
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NSString *const kGPUImageLuminanceThresholdFragmentShaderString = SHADER_STRING
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(
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varying vec2 textureCoordinate;
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uniform sampler2D inputImageTexture;
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uniform float threshold;
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const vec3 W = vec3(0.2125, 0.7154, 0.0721);
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void main()
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{
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vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);
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float luminance = dot(textureColor.rgb, W);
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float thresholdResult = step(threshold, luminance);
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gl_FragColor = vec4(vec3(thresholdResult), textureColor.w);
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}
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);
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#endif
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@implementation GPUImageLuminanceThresholdFilter
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@synthesize threshold = _threshold;
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#pragma mark -
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#pragma mark Initialization
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- (id)init;
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{
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if (!(self = [super initWithFragmentShaderFromString:kGPUImageLuminanceThresholdFragmentShaderString]))
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{
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return nil;
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}
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thresholdUniform = [filterProgram uniformIndex:@"threshold"];
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self.threshold = 0.5;
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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)setThreshold:(CGFloat)newValue;
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{
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_threshold = newValue;
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[self setFloat:_threshold forUniform:thresholdUniform program:filterProgram];
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}
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@end
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