#import "GPUImageStretchDistortionFilter.h"
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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NSString *const kGPUImageStretchDistortionFragmentShaderString = 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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void main()
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{
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highp vec2 normCoord = 2.0 * textureCoordinate - 1.0;
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highp vec2 normCenter = 2.0 * center - 1.0;
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normCoord -= normCenter;
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mediump vec2 s = sign(normCoord);
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normCoord = abs(normCoord);
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normCoord = 0.5 * normCoord + 0.5 * smoothstep(0.25, 0.5, normCoord) * normCoord;
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normCoord = s * normCoord;
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normCoord += normCenter;
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mediump vec2 textureCoordinateToUse = normCoord / 2.0 + 0.5;
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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 kGPUImageStretchDistortionFragmentShaderString = 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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void main()
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{
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vec2 normCoord = 2.0 * textureCoordinate - 1.0;
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vec2 normCenter = 2.0 * center - 1.0;
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normCoord -= normCenter;
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vec2 s = sign(normCoord);
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normCoord = abs(normCoord);
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normCoord = 0.5 * normCoord + 0.5 * smoothstep(0.25, 0.5, normCoord) * normCoord;
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normCoord = s * normCoord;
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normCoord += normCenter;
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vec2 textureCoordinateToUse = normCoord / 2.0 + 0.5;
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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 GPUImageStretchDistortionFilter
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@synthesize center = _center;
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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:kGPUImageStretchDistortionFragmentShaderString]))
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{
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return nil;
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}
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centerUniform = [filterProgram uniformIndex:@"center"];
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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)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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