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Fix integer overflow with diagonal node splits

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Fixes random invisible walls and possibly more errors
This commit is contained in:
LJ Sonic 2022-12-27 20:26:08 +01:00
parent 29b9fec85d
commit 58e5473c9e
1 changed files with 10 additions and 10 deletions
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20
src/r_main.c
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@ -266,13 +266,13 @@ INT32 R_PointOnSide(fixed_t x, fixed_t y, node_t *node)
if (!node->dy)
return y <= node->y ? node->dx < 0 : node->dx > 0;
x -= node->x;
y -= node->y;
fixed_t dx = (x >> 1) - (node->x >> 1);
fixed_t dy = (y >> 1) - (node->y >> 1);
// Try to quickly decide by looking at sign bits.
if ((node->dy ^ node->dx ^ x ^ y) < 0)
return (node->dy ^ x) < 0; // (left is negative)
return FixedMul(y, node->dx>>FRACBITS) >= FixedMul(node->dy>>FRACBITS, x);
if ((node->dy ^ node->dx ^ dx ^ dy) < 0)
return (node->dy ^ dx) < 0; // (left is negative)
return FixedMul(dy, node->dx>>FRACBITS) >= FixedMul(node->dy>>FRACBITS, dx);
}
// killough 5/2/98: reformatted
@ -289,13 +289,13 @@ INT32 R_PointOnSegSide(fixed_t x, fixed_t y, seg_t *line)
if (!ldy)
return y <= ly ? ldx < 0 : ldx > 0;
x -= lx;
y -= ly;
fixed_t dx = (x >> 1) - (lx >> 1);
fixed_t dy = (y >> 1) - (ly >> 1);
// Try to quickly decide by looking at sign bits.
if ((ldy ^ ldx ^ x ^ y) < 0)
return (ldy ^ x) < 0; // (left is negative)
return FixedMul(y, ldx>>FRACBITS) >= FixedMul(ldy>>FRACBITS, x);
if ((ldy ^ ldx ^ dx ^ dy) < 0)
return (ldy ^ dx) < 0; // (left is negative)
return FixedMul(dy, ldx>>FRACBITS) >= FixedMul(ldy>>FRACBITS, dx);
}
//