#import "GPUImageAddBlendFilter.h"
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#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
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NSString *const kGPUImageAddBlendFragmentShaderString = SHADER_STRING
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(
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varying highp vec2 textureCoordinate;
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varying highp vec2 textureCoordinate2;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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void main()
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{
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lowp vec4 base = texture2D(inputImageTexture, textureCoordinate);
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lowp vec4 overlay = texture2D(inputImageTexture2, textureCoordinate2);
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mediump float r;
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if (overlay.r * base.a + base.r * overlay.a >= overlay.a * base.a) {
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r = overlay.a * base.a + overlay.r * (1.0 - base.a) + base.r * (1.0 - overlay.a);
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} else {
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r = overlay.r + base.r;
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}
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mediump float g;
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if (overlay.g * base.a + base.g * overlay.a >= overlay.a * base.a) {
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g = overlay.a * base.a + overlay.g * (1.0 - base.a) + base.g * (1.0 - overlay.a);
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} else {
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g = overlay.g + base.g;
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}
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mediump float b;
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if (overlay.b * base.a + base.b * overlay.a >= overlay.a * base.a) {
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b = overlay.a * base.a + overlay.b * (1.0 - base.a) + base.b * (1.0 - overlay.a);
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} else {
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b = overlay.b + base.b;
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}
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mediump float a = overlay.a + base.a - overlay.a * base.a;
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gl_FragColor = vec4(r, g, b, a);
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}
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);
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#else
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NSString *const kGPUImageAddBlendFragmentShaderString = SHADER_STRING
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(
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varying vec2 textureCoordinate;
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varying vec2 textureCoordinate2;
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uniform sampler2D inputImageTexture;
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uniform sampler2D inputImageTexture2;
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void main()
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{
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vec4 base = texture2D(inputImageTexture, textureCoordinate);
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vec4 overlay = texture2D(inputImageTexture2, textureCoordinate2);
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float r;
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if (overlay.r * base.a + base.r * overlay.a >= overlay.a * base.a) {
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r = overlay.a * base.a + overlay.r * (1.0 - base.a) + base.r * (1.0 - overlay.a);
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} else {
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r = overlay.r + base.r;
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}
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float g;
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if (overlay.g * base.a + base.g * overlay.a >= overlay.a * base.a) {
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g = overlay.a * base.a + overlay.g * (1.0 - base.a) + base.g * (1.0 - overlay.a);
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} else {
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g = overlay.g + base.g;
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}
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float b;
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if (overlay.b * base.a + base.b * overlay.a >= overlay.a * base.a) {
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b = overlay.a * base.a + overlay.b * (1.0 - base.a) + base.b * (1.0 - overlay.a);
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} else {
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b = overlay.b + base.b;
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}
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float a = overlay.a + base.a - overlay.a * base.a;
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gl_FragColor = vec4(r, g, b, a);
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}
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);
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#endif
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@implementation GPUImageAddBlendFilter
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- (id)init;
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{
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if (!(self = [super initWithFragmentShaderFromString:kGPUImageAddBlendFragmentShaderString]))
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{
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return nil;
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}
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return self;
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}
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@end
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