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comparing Vector(-2, 0, 0) and Vector(2, 0, 0) was returning true, this bug is years old, strange nobody noticed.

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use float comparison from the "Ever Faster Float Comparisons" paper, tested with random values as well as random values converted to ints (where this existing code would fail).
This commit is contained in:
Campbell Barton
2010-02-28 19:27:06 +00:00
parent 9e35777019
commit 5455917274
2 changed files with 18 additions and 24 deletions
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35
source/blender/python/generic/Mathutils.c
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@@ -557,25 +557,24 @@ static PyObject *M_Mathutils_ShearMatrix(PyObject * self, PyObject * args)
/* Utility functions */
/*---------------------- EXPP_FloatsAreEqual -------------------------
Floating point comparisons
floatStep = number of representable floats allowable in between
float A and float B to be considered equal. */
int EXPP_FloatsAreEqual(float A, float B, int floatSteps)
{
int a, b, delta;
assert(floatSteps > 0 && floatSteps < (4 * 1024 * 1024));
a = *(int*)&A;
if (a < 0)
a = 0x80000000 - a;
b = *(int*)&B;
if (b < 0)
b = 0x80000000 - b;
delta = abs(a - b);
if (delta <= floatSteps)
return 1;
return 0;
// LomontRRDCompare4, Ever Faster Float Comparisons by Randy Dillon
#define SIGNMASK(i) (-(int)(((unsigned int)(i))>>31))
int EXPP_FloatsAreEqual(float af, float bf, int maxDiff)
{ // solid, fast routine across all platforms
// with constant time behavior
int ai = *(int *)(&af);
int bi = *(int *)(&bf);
int test = SIGNMASK(ai^bi);
int diff, v1, v2;
assert((0 == test) || (0xFFFFFFFF == test));
diff = (ai ^ (test & 0x7fffffff)) - bi;
v1 = maxDiff + diff;
v2 = maxDiff - diff;
return (v1|v2) >= 0;
}
/*---------------------- EXPP_VectorsAreEqual -------------------------
Builds on EXPP_FloatsAreEqual to test vectors */
int EXPP_VectorsAreEqual(float *vecA, float *vecB, int size, int floatSteps)