Skip to content

Instantly share code, notes, and snippets.

@BreadFish64
Created December 14, 2020 23:48
Show Gist options
  • Save BreadFish64/8fd2829fc0243a41583b248f9c203f20 to your computer and use it in GitHub Desktop.
Save BreadFish64/8fd2829fc0243a41583b248f9c203f20 to your computer and use it in GitHub Desktop.
#version 330
in vec2 TexCoord;
out vec4 FragColor;
uniform sampler2D Texture;
vec3 dtt = vec3(65536.0,255.0,1.0);
float reduce(vec3 color)
{
return dot(color, dtt);
}
/* GET_RESULT function */
/* Copyright (c) 1999-2001 by Derek Liauw Kie Fa */
/* License: GNU-GPL */
int GET_RESULT(float A, float B, float C, float D)
{
int x = 0; int y = 0; int r = 0;
if (A == C) x+=1; else if (B == C) y+=1;
if (A == D) x+=1; else if (B == D) y+=1;
if (x <= 1) r+=1;
if (y <= 1) r-=1;
return r;
}
void main()
{
vec2 fp = fract(TexCoord * textureSize(Texture, 0).xy);
// Reading the texels
vec3 C0 = textureOffset(Texture, TexCoord, ivec2(-1, -1)).xyz;
vec3 C1 = textureOffset(Texture, TexCoord, ivec2(-1, 0)).xyz;
vec3 C2 = textureOffset(Texture, TexCoord, ivec2(1, -1)).xyz;
vec3 D3 = textureOffset(Texture, TexCoord, ivec2(2, -1)).xyz;
vec3 C3 = textureOffset(Texture, TexCoord, ivec2(-1, 0)).xyz;
vec3 C4 = texture(Texture, TexCoord).xyz;
vec3 C5 = textureOffset(Texture, TexCoord, ivec2(1, 0)).xyz;
vec3 D4 = textureOffset(Texture, TexCoord, ivec2(2, 0)).xyz;
vec3 C6 = textureOffset(Texture, TexCoord, ivec2(-1, 1)).xyz;
vec3 C7 = textureOffset(Texture, TexCoord, ivec2(0, 1)).xyz;
vec3 C8 = textureOffset(Texture, TexCoord, ivec2(1, 1)).xyz;
vec3 D5 = textureOffset(Texture, TexCoord, ivec2(2, 1)).xyz;
vec3 D0 = textureOffset(Texture, TexCoord, ivec2(-1, 2)).xyz;
vec3 D1 = textureOffset(Texture, TexCoord, ivec2(0, 2)).xyz;
vec3 D2 = textureOffset(Texture, TexCoord, ivec2(1, 2)).xyz;
vec3 D6 = textureOffset(Texture, TexCoord, ivec2(2, 2)).xyz;
vec3 p00,p10,p01,p11;
// reducing vec3 to float
float c0 = reduce(C0);float c1 = reduce(C1);
float c2 = reduce(C2);float c3 = reduce(C3);
float c4 = reduce(C4);float c5 = reduce(C5);
float c6 = reduce(C6);float c7 = reduce(C7);
float c8 = reduce(C8);float d0 = reduce(D0);
float d1 = reduce(D1);float d2 = reduce(D2);
float d3 = reduce(D3);float d4 = reduce(D4);
float d5 = reduce(D5);float d6 = reduce(D6);
/* SuperEagle code */
/* Copied from the Dosbox source code */
/* Copyright (C) 2002-2007 The DOSBox Team */
/* License: GNU-GPL */
/* Adapted by guest(r) on 16.4.2007 */
if (c4 != c8) {
if (c7 == c5) {
p01 = p10 = C7;
if ((c6 == c7) || (c5 == c2)) {
p00 = 0.25*(3.0*C7+C4);
} else {
p00 = 0.5*(C4+C5);
}
if ((c5 == d4) || (c7 == d1)) {
p11 = 0.25*(3.0*C7+C8);
} else {
p11 = 0.5*(C7+C8);
}
} else {
p11 = 0.125*(6.0*C8+C7+C5);
p00 = 0.125*(6.0*C4+C7+C5);
p10 = 0.125*(6.0*C7+C4+C8);
p01 = 0.125*(6.0*C5+C4+C8);
}
} else {
if (c7 != c5) {
p11 = p00 = C4;
if ((c1 == c4) || (c8 == d5)) {
p01 = 0.25*(3.0*C4+C5);
} else {
p01 = 0.5*(C4+C5);
}
if ((c8 == d2) || (c3 == c4)) {
p10 = 0.25*(3.0*C4+C7);
} else {
p10 = 0.5*(C7+C8);
}
} else {
int r = 0;
r += GET_RESULT(c5,c4,c6,d1);
r += GET_RESULT(c5,c4,c3,c1);
r += GET_RESULT(c5,c4,d2,d5);
r += GET_RESULT(c5,c4,c2,d4);
if (r > 0) {
p01 = p10 = C7;
p00 = p11 = 0.5*(C4+C5);
} else if (r < 0) {
p11 = p00 = C4;
p01 = p10 = 0.5*(C4+C5);
} else {
p11 = p00 = C4;
p01 = p10 = C7;
}
}
}
// Distributing the four products
p10 = (fp.x < 0.50) ? (fp.y < 0.50 ? p00 : p10) : (fp.y < 0.50 ? p01: p11);
FragColor = vec4(p10, 1.0);
}
#version 330
out vec2 TexCoord;
const vec2 VertexCoords[4] =
vec2[4](vec2(-1.0, -1.0), vec2(1.0, -1.0), vec2(-1.0, 1.0), vec2(1.0, 1.0));
void main()
{
vec2 VertexCoord = VertexCoords[gl_VertexID];
gl_Position = vec4(VertexCoord, 0, 1);
TexCoord = (VertexCoord + 1) / 2;
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment