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Merge pull request #446 from T4Larson/slerpfix

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fix: btQuaternion.slerp() may result in NaN-quaternions
This commit is contained in:
erwincoumans
2016-09-23 22:03:01 -07:00
committed by GitHub
parent 80ea081189 6c71f37da1
commit d3bf740c50
1 changed files with 21 additions and 17 deletions
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38
src/LinearMath/btQuaternion.h
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@@ -532,25 +532,29 @@ public:
* Slerp interpolates assuming constant velocity. */ * Slerp interpolates assuming constant velocity. */
btQuaternion slerp(const btQuaternion& q, const btScalar& t) const btQuaternion slerp(const btQuaternion& q, const btScalar& t) const
{ {
btScalar magnitude = btSqrt(length2() * q.length2());
btAssert(magnitude > btScalar(0));
btScalar product = dot(q) / magnitude; const btScalar magnitude = btSqrt(length2() * q.length2());
if (btFabs(product) < btScalar(1)) btAssert(magnitude > btScalar(0));
const btScalar product = dot(q) / magnitude;
const btScalar absproduct = btFabs(product);
if(absproduct < btScalar(1.0 - SIMD_EPSILON))
{ {
// Take care of long angle case see http://en.wikipedia.org/wiki/Slerp // Take care of long angle case see http://en.wikipedia.org/wiki/Slerp
const btScalar sign = (product < 0) ? btScalar(-1) : btScalar(1); const btScalar theta = btAcos(absproduct);
const btScalar d = btSin(theta);
const btScalar theta = btAcos(sign * product); btAssert(d > btScalar(0))
const btScalar s1 = btSin(sign * t * theta);
const btScalar d = btScalar(1.0) / btSin(theta); const btScalar sign = (product < 0) ? btScalar(-1) : btScalar(1);
const btScalar s0 = btSin((btScalar(1.0) - t) * theta); const btScalar s0 = btSin((btScalar(1.0) - t) * theta) / d;
const btScalar s1 = btSin(sign * t * theta) / d;
return btQuaternion(
(m_floats[0] * s0 + q.x() * s1) * d, return btQuaternion(
(m_floats[1] * s0 + q.y() * s1) * d, (m_floats[0] * s0 + q.x() * s1),
(m_floats[2] * s0 + q.z() * s1) * d, (m_floats[1] * s0 + q.y() * s1),
(m_floats[3] * s0 + q.m_floats[3] * s1) * d); (m_floats[2] * s0 + q.z() * s1),
(m_floats[3] * s0 + q.w() * s1));
} }
else else
{ {