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fix btQuaternion::slerp

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See issue 583.
Thanks to macbearchen for the report and joshua downer for the fix
This commit is contained in:
erwin.coumans
2012-02-29 04:50:39 +00:00
parent 018c526edc
commit 8f389d13e7
1 changed files with 18 additions and 16 deletions
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34
src/LinearMath/btQuaternion.h
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@@ -280,23 +280,25 @@ public:
* Slerp interpolates assuming constant velocity. */
btQuaternion slerp(const btQuaternion& q, const btScalar& t) const
{
btScalar theta = angle(q);
if (theta != btScalar(0.0))
btScalar magnitude = btSqrt(length2() * q.length2());
btAssert(magnitude > btScalar(0));
btScalar product = dot(q) / magnitude;
if (btFabs(product) != btScalar(1))
{
btScalar d = btScalar(1.0) / btSin(theta);
btScalar s0 = btSin((btScalar(1.0) - t) * theta);
btScalar s1 = btSin(t * theta);
if (dot(q) < 0) // Take care of long angle case see http://en.wikipedia.org/wiki/Slerp
return btQuaternion((m_floats[0] * s0 + -q.x() * s1) * d,
(m_floats[1] * s0 + -q.y() * s1) * d,
(m_floats[2] * s0 + -q.z() * s1) * d,
(m_floats[3] * s0 + -q.m_floats[3] * s1) * d);
else
return btQuaternion((m_floats[0] * s0 + q.x() * s1) * d,
(m_floats[1] * s0 + q.y() * s1) * d,
(m_floats[2] * s0 + q.z() * s1) * d,
(m_floats[3] * s0 + q.m_floats[3] * s1) * d);
// 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(sign * product);
const btScalar s1 = btSin(sign * t * theta);
const btScalar d = btScalar(1.0) / btSin(theta);
const btScalar s0 = btSin((btScalar(1.0) - t) * theta);
return btQuaternion(
(m_floats[0] * s0 + q.x() * s1) * d,
(m_floats[1] * s0 + q.y() * s1) * d,
(m_floats[2] * s0 + q.z() * s1) * d,
(m_floats[3] * s0 + q.m_floats[3] * s1) * d);
}
else
{