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Use signed integers for interpolation in marching squares algorithm #7814

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Merged
StephenCWills merged 1 commit into from
Mar 7, 2025
Merged

Use signed integers for interpolation in marching squares algorithm #7814

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8 changes: 5 additions & 3 deletions Source/engine/render/light_render.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -85,11 +85,13 @@ void RenderTriangle(Point p1, Point p2, Point p3, uint8_t lightLevel, uint8_t *l
}
}

uint8_t Interpolate(uint8_t q1, uint8_t q2, uint8_t lightLevel)
uint8_t Interpolate(int q1, int q2, int lightLevel)
{
// Result will be 28.4 fixed-point
uint8_t numerator = (lightLevel - q1) << 4;
return (numerator + 0x8) / (q2 - q1);
int numerator = (lightLevel - q1) << 4;
int result = (numerator + 0x8) / (q2 - q1);
assert(result >= 0);
return static_cast<uint8_t>(result);
}

void RenderCell(uint8_t quad[4], Point position, uint8_t lightLevel, uint8_t *lightmap, uint16_t pitch, uint16_t scanLines)
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