SameBoy | Accurate GB/GBC emulator |
| download: https://git.y1.nz/archives/sameboy.tar.gz | |
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Shaders/Scale2x.fsh
1 /* Shader implementation of Scale2x is adapted from https://gist.github.com/singron/3161079 */
2
3 STATIC vec4 scale(sampler2D image, vec2 position, vec2 input_resolution, vec2 output_resolution)
4 {
5 // texel arrangement
6 // A B C
7 // D E F
8 // G H I
9
10 vec4 B = texture_relative(image, position, vec2( 0, 1));
11 vec4 D = texture_relative(image, position, vec2( -1, 0));
12 vec4 E = texture_relative(image, position, vec2( 0, 0));
13 vec4 F = texture_relative(image, position, vec2( 1, 0));
14 vec4 H = texture_relative(image, position, vec2( 0, -1));
15 vec2 p = position * input_resolution;
16 // p = the position within a pixel [0...1]
17 p = fract(p);
18 if (p.x > .5) {
19 if (p.y > .5) {
20 // Top Right
21 return equal(B, F) && inequal(B, D) && inequal(F, H) ? F : E;
22 } else {
23 // Bottom Right
24 return equal(H, F) && inequal(D, H) && inequal(B, F) ? F : E;
25 }
26 } else {
27 if (p.y > .5) {
28 // Top Left
29 return equal(D, B) && inequal(B, F) && inequal(D, H) ? D : E;
30 } else {
31 // Bottom Left
32 return equal(D, H) && inequal(D, B) && inequal(H, F) ? D : E;
33 }
34 }
35 }
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