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Lua palette quantization #802

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Lua palette quantization #802

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c2bba93
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warmCabin Aug 10, 2025
9ca2036
comment out index_lookup (for now)
warmCabin Aug 10, 2025
adb1c9c
change scoring to basic distance squared
warmCabin Aug 10, 2025
d4c0ece
reenable index_lookup, for science
warmCabin Aug 11, 2025
2152c04
do a 5-bit lookup table
warmCabin Aug 11, 2025
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20 changes: 10 additions & 10 deletions src/lua-engine.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3745,31 +3745,31 @@ enum
* ourselves.
*/
static uint8 gui_colour_rgb(uint8 r, uint8 g, uint8 b) {
static uint8 index_lookup[1 << (3+3+3)];
int k;
static uint8 index_lookup[1 << (5+5+5)];

if (!gui_saw_current_palette)
{
memset(index_lookup, GUI_COLOUR_CLEAR, sizeof(index_lookup));
gui_saw_current_palette = TRUE;
}

k = ((r & 0xE0) << 1) | ((g & 0xE0) >> 2) | ((b & 0xE0) >> 5);
// Cache based on upper 5 bits of r, g, and b
int k = ((r & 0xF8) << 7) | ((g & 0xF8) << 2) | ((b & 0xF8) >> 3);
if (index_lookup[k] != GUI_COLOUR_CLEAR) return index_lookup[k];
uint16 test, best = GUI_COLOUR_CLEAR;
uint32 best_score = 0xffffffffu, test_score;
if (index_lookup[k] != GUI_COLOUR_CLEAR) return index_lookup[k];
uint32 test_score, best_score = 0xffffffffu;
for (test = 0; test < 0xff; test++)
{
uint8 tr, tg, tb;
if (test == GUI_COLOUR_CLEAR) continue;
FCEUD_GetPalette(test, &tr, &tg, &tb);
test_score = abs(r - tr) * 66 +
abs(g - tg) * 129 +
abs(b - tb) * 25;
// Basic distance squared
test_score = (r - tr) * (r - tr) +
(g - tg) * (g - tg) +
(b - tb) * (b - tb);
if (test_score < best_score) best_score = test_score, best = test;
}
index_lookup[k] = best;
return best;
return index_lookup[k] = best;
}

void FCEU_LuaUpdatePalette()
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