#import "GPUImageBoxBlurFilter.h"
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@implementation GPUImageBoxBlurFilter
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+ (NSString *)vertexShaderForOptimizedBlurOfRadius:(NSUInteger)blurRadius sigma:(CGFloat)sigma;
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{
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if (blurRadius < 1)
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{
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return kGPUImageVertexShaderString;
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}
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// From these weights we calculate the offsets to read interpolated values from
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NSUInteger numberOfOptimizedOffsets = MIN(blurRadius / 2 + (blurRadius % 2), 7);
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NSMutableString *shaderString = [[NSMutableString alloc] init];
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// Header
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[shaderString appendFormat:@"\
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attribute vec4 position;\n\
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attribute vec4 inputTextureCoordinate;\n\
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\n\
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uniform float texelWidthOffset;\n\
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uniform float texelHeightOffset;\n\
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\n\
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varying vec2 blurCoordinates[%lu];\n\
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\n\
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void main()\n\
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{\n\
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gl_Position = position;\n\
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\n\
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vec2 singleStepOffset = vec2(texelWidthOffset, texelHeightOffset);\n", (unsigned long)(1 + (numberOfOptimizedOffsets * 2))];
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// Inner offset loop
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[shaderString appendString:@"blurCoordinates[0] = inputTextureCoordinate.xy;\n"];
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for (NSUInteger currentOptimizedOffset = 0; currentOptimizedOffset < numberOfOptimizedOffsets; currentOptimizedOffset++)
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{
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GLfloat optimizedOffset = (GLfloat)(currentOptimizedOffset * 2) + 1.5;
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[shaderString appendFormat:@"\
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blurCoordinates[%lu] = inputTextureCoordinate.xy + singleStepOffset * %f;\n\
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blurCoordinates[%lu] = inputTextureCoordinate.xy - singleStepOffset * %f;\n", (unsigned long)((currentOptimizedOffset * 2) + 1), optimizedOffset, (unsigned long)((currentOptimizedOffset * 2) + 2), optimizedOffset];
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}
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// Footer
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[shaderString appendString:@"}\n"];
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return shaderString;
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}
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+ (NSString *)fragmentShaderForOptimizedBlurOfRadius:(NSUInteger)blurRadius sigma:(CGFloat)sigma;
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{
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if (blurRadius < 1)
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{
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return kGPUImagePassthroughFragmentShaderString;
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}
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NSUInteger numberOfOptimizedOffsets = MIN(blurRadius / 2 + (blurRadius % 2), 7);
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NSUInteger trueNumberOfOptimizedOffsets = blurRadius / 2 + (blurRadius % 2);
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NSMutableString *shaderString = [[NSMutableString alloc] init];
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// Header
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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[shaderString appendFormat:@"\
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uniform sampler2D inputImageTexture;\n\
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uniform highp float texelWidthOffset;\n\
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uniform highp float texelHeightOffset;\n\
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\n\
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varying highp vec2 blurCoordinates[%lu];\n\
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\n\
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void main()\n\
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{\n\
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lowp vec4 sum = vec4(0.0);\n", (unsigned long)(1 + (numberOfOptimizedOffsets * 2)) ];
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#else
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[shaderString appendFormat:@"\
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uniform sampler2D inputImageTexture;\n\
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uniform float texelWidthOffset;\n\
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uniform float texelHeightOffset;\n\
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\n\
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varying vec2 blurCoordinates[%lu];\n\
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\n\
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void main()\n\
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{\n\
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vec4 sum = vec4(0.0);\n", 1 + (numberOfOptimizedOffsets * 2) ];
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#endif
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GLfloat boxWeight = 1.0 / (GLfloat)((blurRadius * 2) + 1);
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// Inner texture loop
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[shaderString appendFormat:@"sum += texture2D(inputImageTexture, blurCoordinates[0]) * %f;\n", boxWeight];
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for (NSUInteger currentBlurCoordinateIndex = 0; currentBlurCoordinateIndex < numberOfOptimizedOffsets; currentBlurCoordinateIndex++)
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{
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[shaderString appendFormat:@"sum += texture2D(inputImageTexture, blurCoordinates[%lu]) * %f;\n", (unsigned long)((currentBlurCoordinateIndex * 2) + 1), boxWeight * 2.0];
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[shaderString appendFormat:@"sum += texture2D(inputImageTexture, blurCoordinates[%lu]) * %f;\n", (unsigned long)((currentBlurCoordinateIndex * 2) + 2), boxWeight * 2.0];
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}
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// If the number of required samples exceeds the amount we can pass in via varyings, we have to do dependent texture reads in the fragment shader
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if (trueNumberOfOptimizedOffsets > numberOfOptimizedOffsets)
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{
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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[shaderString appendString:@"highp vec2 singleStepOffset = vec2(texelWidthOffset, texelHeightOffset);\n"];
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#else
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[shaderString appendString:@"vec2 singleStepOffset = vec2(texelWidthOffset, texelHeightOffset);\n"];
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#endif
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for (NSUInteger currentOverlowTextureRead = numberOfOptimizedOffsets; currentOverlowTextureRead < trueNumberOfOptimizedOffsets; currentOverlowTextureRead++)
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{
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GLfloat optimizedOffset = (GLfloat)(currentOverlowTextureRead * 2) + 1.5;
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[shaderString appendFormat:@"sum += texture2D(inputImageTexture, blurCoordinates[0] + singleStepOffset * %f) * %f;\n", optimizedOffset, boxWeight * 2.0];
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[shaderString appendFormat:@"sum += texture2D(inputImageTexture, blurCoordinates[0] - singleStepOffset * %f) * %f;\n", optimizedOffset, boxWeight * 2.0];
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}
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}
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// Footer
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[shaderString appendString:@"\
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gl_FragColor = sum;\n\
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}\n"];
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return shaderString;
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}
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- (void)setupFilterForSize:(CGSize)filterFrameSize;
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{
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[super setupFilterForSize:filterFrameSize];
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if (shouldResizeBlurRadiusWithImageSize == YES)
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{
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}
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}
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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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// NSString *currentGaussianBlurVertexShader = [GPUImageGaussianBlurFilter vertexShaderForStandardGaussianOfRadius:4 sigma:2.0];
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// NSString *currentGaussianBlurFragmentShader = [GPUImageGaussianBlurFilter fragmentShaderForStandardGaussianOfRadius:4 sigma:2.0];
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NSString *currentBoxBlurVertexShader = [[self class] vertexShaderForOptimizedBlurOfRadius:4 sigma:0.0];
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NSString *currentBoxBlurFragmentShader = [[self class] fragmentShaderForOptimizedBlurOfRadius:4 sigma:0.0];
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if (!(self = [super initWithFirstStageVertexShaderFromString:currentBoxBlurVertexShader firstStageFragmentShaderFromString:currentBoxBlurFragmentShader secondStageVertexShaderFromString:currentBoxBlurVertexShader secondStageFragmentShaderFromString:currentBoxBlurFragmentShader]))
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{
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return nil;
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}
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_blurRadiusInPixels = 4.0;
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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)setBlurRadiusInPixels:(CGFloat)newValue;
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{
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CGFloat newBlurRadius = round(round(newValue / 2.0) * 2.0); // For now, only do even radii
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if (newBlurRadius != _blurRadiusInPixels)
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{
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_blurRadiusInPixels = newBlurRadius;
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NSString *newGaussianBlurVertexShader = [[self class] vertexShaderForOptimizedBlurOfRadius:_blurRadiusInPixels sigma:0.0];
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NSString *newGaussianBlurFragmentShader = [[self class] fragmentShaderForOptimizedBlurOfRadius:_blurRadiusInPixels sigma:0.0];
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// NSLog(@"Optimized vertex shader: \n%@", newGaussianBlurVertexShader);
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// NSLog(@"Optimized fragment shader: \n%@", newGaussianBlurFragmentShader);
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//
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[self switchToVertexShader:newGaussianBlurVertexShader fragmentShader:newGaussianBlurFragmentShader];
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}
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shouldResizeBlurRadiusWithImageSize = NO;
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}
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@end
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