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Author: rambetter

Browse Source 
Date: Tue Dec 28 04:02:11 2010
New Revision: 371

Rewriting BaseWindingForPlane() in polylib.c from the ground up.  The behavior is totally unchanged, and I verified this by running extensive tests.  The only difference is that the math precision is much much better now.  Performance should be better as well (but that is not tested).  This is a major milestone because it fixes two regression tests: disappearing_sliver2 and sparkly_seam.
Improvements to math precision is ongoing and more improvements can probably be made even after this patch.
I will update the README.txt files in the regression tests in a separate commit.  This commit only includes the actual fixed code.
This commit is contained in:
Rudolf Polzer
2010-12-28 11:24:25 +01:00
parent bbcc70e072
commit ec64df5697
3 changed files with 93 additions and 0 deletions
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77
tools/quake3/common/polylib.c
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@@ -207,6 +207,83 @@ BaseWindingForPlane
=================
*/
winding_t *BaseWindingForPlane (vec3_t normal, vec_t dist)
{
// The goal in this function is to replicate the exact behavior that was in the original
// BaseWindingForPlane() function (see below). The only thing we're going to change is the
// accuracy of the operation. The original code gave a preference for the vup vector to start
// out as (0, 0, 1), unless the normal had a dominant Z value, in which case vup started out
// as (1, 0, 0). After that, vup was "bent" [along the plane defined by normal and vup] to
// become perpendicular to normal. After that the vright vector was computed as the cross
// product of vup and normal.
// Once these vectors are calculated, I'm constructing the winding points in exactly the same
// way as was done in the original function. Orientation is the same.
// Note that the 4 points in the returned winding_t may actually not be necessary (3 might
// be enough). However, I want to minimize the chance of ANY bugs popping up due to any
// change in behavior of this function. Therefore, behavior stays exactly the same, except
// for precision of math. Performance might be better in the new function as well.
int x, i;
vec_t max, v;
vec3_t vright, vup, org;
winding_t *w;
max = -BOGUS_RANGE;
x = -1;
for (i = 0; i < 3; i++) {
v = fabs(normal[i]);
if (v > max) {
x = i;
max = v;
}
}
if (x == -1) Error("BaseWindingForPlane: no axis found");
switch (x) {
case 0: // Fall through to next case.
case 1:
vright[0] = -normal[1];
vright[1] = normal[0];
vright[2] = 0;
break;
case 2:
vright[0] = 0;
vright[1] = -normal[2];
vright[2] = normal[1];
break;
}
CrossProduct(normal, vright, vup);
// IMPORTANT NOTE: vright and vup are NOT unit vectors at this point.
// However, normal, vup, and vright are pairwise perpendicular.
VectorSetLength(vup, MAX_WORLD_COORD * 2, vup);
VectorSetLength(vright, MAX_WORLD_COORD * 2, vright);
VectorScale(normal, dist, org);
w = AllocWinding(4);
VectorSubtract(org, vright, w->p[0]);
VectorAdd(w->p[0], vup, w->p[0]);
VectorAdd(org, vright, w->p[1]);
VectorAdd(w->p[1], vup, w->p[1]);
VectorAdd(org, vright, w->p[2]);
VectorSubtract(w->p[2], vup, w->p[2]);
VectorSubtract(org, vright, w->p[3]);
VectorSubtract(w->p[3], vup, w->p[3]);
w->numpoints = 4;
return w;
}
// Old function, not used but here for reference. Please do not modify it.
// (You may remove it at some point.)
winding_t *_BaseWindingForPlane_orig_(vec3_t normal, vec_t dist)
{
int i, x;
vec_t max, v;