bsnes/pixelshaders/Scale2x/fragment

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//Scale2x GLSL shader
//license: GPL
//original version by Pete Bernert
//ruby port by byuu
uniform sampler2D rubyTexture;
uniform vec2 rubyTextureSize;
void main() {
vec4 colD, colF, colB, colH, col, tmp;
vec2 sel;
col = texture2DProj(rubyTexture, gl_TexCoord[0]); //central (can be E0-E3)
colD = texture2DProj(rubyTexture, gl_TexCoord[1]); //D (left)
colF = texture2DProj(rubyTexture, gl_TexCoord[2]); //F (right)
colB = texture2DProj(rubyTexture, gl_TexCoord[3]); //B (top)
colH = texture2DProj(rubyTexture, gl_TexCoord[4]); //H (bottom)
sel = fract(gl_TexCoord[0].xy * rubyTextureSize.xy); //where are we (E0-E3)?
//E0 is default
if(sel.y >= 0.5) { tmp = colB; colB = colH; colH = tmp; } //E1 (or E3): swap B and H
if(sel.x >= 0.5) { tmp = colF; colF = colD; colD = tmp; } //E2 (or E3): swap D and F
if(colB == colD && colB != colF && colD != colH) { //do the Scale2x rule
col = colD;
}
gl_FragColor = col;
}