mgba/res/shaders/scale2x.shader/scale2x.fs

40 lines
1.1 KiB
Forth
Raw Normal View History

2021-06-25 00:35:16 +00:00
/* Shader implementation of Scale2x is adapted from https://gist.github.com/singron/3161079 */
varying vec2 texCoord;
uniform sampler2D tex;
uniform vec2 texSize;
void main() {
// o = offset, the width of a pixel
vec2 o = 1.0 / texSize;
// texel arrangement
// A B C
// D E F
// G H I
vec4 B = texture2D(tex, texCoord + vec2( 0.0, o.y));
vec4 D = texture2D(tex, texCoord + vec2( -o.x, 0.0));
vec4 E = texture2D(tex, texCoord + vec2( 0.0, 0.0));
vec4 F = texture2D(tex, texCoord + vec2( o.x, 0.0));
vec4 H = texture2D(tex, texCoord + vec2( 0.0, -o.y));
vec2 p = texCoord * texSize;
// p = the texCoord within a pixel [0...1]
p = fract(p);
if (p.x > .5) {
if (p.y > .5) {
// Top Right
gl_FragColor = B == F && B != D && F != H ? F : E;
} else {
// Bottom Right
gl_FragColor = H == F && D != H && B != F ? F : E;
}
} else {
if (p.y > .5) {
// Top Left
gl_FragColor = D == B && B != F && D != H ? D : E;
} else {
// Bottom Left
gl_FragColor = D == H && D != B && H != F ? D : E;
}
}
}