#import "GPUImageExclusionBlendFilter.h"

#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
NSString *const kGPUImageExclusionBlendFragmentShaderString = SHADER_STRING
(
 varying highp vec2 textureCoordinate;
 varying highp vec2 textureCoordinate2;

 uniform sampler2D inputImageTexture;
 uniform sampler2D inputImageTexture2;
 
 void main()
 {
     mediump vec4 base = texture2D(inputImageTexture, textureCoordinate);
     mediump vec4 overlay = texture2D(inputImageTexture2, textureCoordinate2);
     
     //     Dca = (Sca.Da + Dca.Sa - 2.Sca.Dca) + Sca.(1 - Da) + Dca.(1 - Sa)
     
     gl_FragColor = vec4((overlay.rgb * base.a + base.rgb * overlay.a - 2.0 * overlay.rgb * base.rgb) + overlay.rgb * (1.0 - base.a) + base.rgb * (1.0 - overlay.a), base.a);
 }
);
#else
NSString *const kGPUImageExclusionBlendFragmentShaderString = SHADER_STRING
(
 varying vec2 textureCoordinate;
 varying vec2 textureCoordinate2;
 
 uniform sampler2D inputImageTexture;
 uniform sampler2D inputImageTexture2;
 
 void main()
 {
     vec4 base = texture2D(inputImageTexture, textureCoordinate);
     vec4 overlay = texture2D(inputImageTexture2, textureCoordinate2);
     
     //     Dca = (Sca.Da + Dca.Sa - 2.Sca.Dca) + Sca.(1 - Da) + Dca.(1 - Sa)
     
     gl_FragColor = vec4((overlay.rgb * base.a + base.rgb * overlay.a - 2.0 * overlay.rgb * base.rgb) + overlay.rgb * (1.0 - base.a) + base.rgb * (1.0 - overlay.a), base.a);
 }
 );
#endif

@implementation GPUImageExclusionBlendFilter

- (id)init;
{
    if (!(self = [super initWithFragmentShaderFromString:kGPUImageExclusionBlendFragmentShaderString]))
    {
		return nil;
    }
    
    return self;
}

@end