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Check convex quads

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This commit is contained in:
Miloslav Ciz 2025-02-01 19:57:33 +01:00
parent 19d3c1cbe5
commit 4cb558b85c
4 changed files with 31 additions and 5 deletions
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28
renderer.h
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@ -252,6 +252,31 @@ void LCR_rendererDrawText(const char *text, int x, int y, uint16_t color,
}
}
/**
Guesses (not 100% accurately) if a quad is convex or not.
*/
int _LCR_rendererQuadLooksConvex(S3L_Unit quad[8])
{
S3L_Unit cx = (quad[0] + quad[2] + quad[4] + quad[6]) / 4;
S3L_Unit cy = (quad[1] + quad[3] + quad[5] + quad[7]) / 4;
S3L_Unit r = 0;
for (int i = 0; i < 8; i += 2)
{
r += S3L_abs(cx - quad[i]);
r += S3L_abs(cy - quad[i + 1]);
}
r = (3 * r) / 32;
for (int i = 0; i < 8; i += 2)
if (S3L_abs(cx - quad[i]) <= r && S3L_abs(cy - quad[i + 1]) <= r)
return 0;
return 1;
}
uint16_t _LCR_pixelColor = 0; /**< Holds pixel color for _LCR_pixelFunc3D. This
is needed is texture subsampling is on. */
@ -631,7 +656,8 @@ uint8_t _LCR_rendererCheckMapTriCover(const S3L_Index *t1,
points2D[13] = (4 * points2D[7] + 3 * points2D[9] + points2D[11]) / 8;
// first: does the triangle alone cover the other one?
if (_LCR_rendererQuadCoversTri(points2D + 6,points2D))
if (_LCR_rendererQuadLooksConvex(points2D +6) &&
_LCR_rendererQuadCoversTri(points2D + 6,points2D))
result |= 1 << j;
else
{