#import "GPUImageSwirlFilter.h"
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// Adapted from the shader example here: http://www.geeks3d.com/20110428/shader-library-swirl-post-processing-filter-in-glsl/
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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NSString *const kGPUImageSwirlFragmentShaderString = 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 vec2 center;
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uniform highp float radius;
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uniform highp float angle;
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void main()
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{
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highp vec2 textureCoordinateToUse = textureCoordinate;
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highp float dist = distance(center, textureCoordinate);
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if (dist < radius)
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{
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textureCoordinateToUse -= center;
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highp float percent = (radius - dist) / radius;
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highp float theta = percent * percent * angle * 8.0;
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highp float s = sin(theta);
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highp float c = cos(theta);
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textureCoordinateToUse = vec2(dot(textureCoordinateToUse, vec2(c, -s)), dot(textureCoordinateToUse, vec2(s, c)));
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textureCoordinateToUse += center;
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}
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gl_FragColor = texture2D(inputImageTexture, textureCoordinateToUse );
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}
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);
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#else
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NSString *const kGPUImageSwirlFragmentShaderString = 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 vec2 center;
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uniform float radius;
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uniform float angle;
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void main()
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{
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vec2 textureCoordinateToUse = textureCoordinate;
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float dist = distance(center, textureCoordinate);
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if (dist < radius)
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{
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textureCoordinateToUse -= center;
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float percent = (radius - dist) / radius;
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float theta = percent * percent * angle * 8.0;
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float s = sin(theta);
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float c = cos(theta);
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textureCoordinateToUse = vec2(dot(textureCoordinateToUse, vec2(c, -s)), dot(textureCoordinateToUse, vec2(s, c)));
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textureCoordinateToUse += center;
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}
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gl_FragColor = texture2D(inputImageTexture, textureCoordinateToUse );
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}
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);
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#endif
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@implementation GPUImageSwirlFilter
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@synthesize center = _center;
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@synthesize radius = _radius;
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@synthesize angle = _angle;
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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:kGPUImageSwirlFragmentShaderString]))
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{
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return nil;
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}
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radiusUniform = [filterProgram uniformIndex:@"radius"];
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angleUniform = [filterProgram uniformIndex:@"angle"];
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centerUniform = [filterProgram uniformIndex:@"center"];
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self.radius = 0.5;
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self.angle = 1.0;
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self.center = CGPointMake(0.5, 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)setInputRotation:(GPUImageRotationMode)newInputRotation atIndex:(NSInteger)textureIndex;
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{
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[super setInputRotation:newInputRotation atIndex:textureIndex];
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[self setCenter:self.center];
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}
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- (void)setRadius:(CGFloat)newValue;
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{
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_radius = newValue;
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[self setFloat:_radius forUniform:radiusUniform program:filterProgram];
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}
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- (void)setAngle:(CGFloat)newValue;
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{
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_angle = newValue;
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[self setFloat:_angle forUniform:angleUniform program:filterProgram];
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}
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- (void)setCenter:(CGPoint)newValue;
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{
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_center = newValue;
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CGPoint rotatedPoint = [self rotatedPoint:_center forRotation:inputRotation];
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[self setPoint:rotatedPoint forUniform:centerUniform program:filterProgram];
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}
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@end
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