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Resolved quaternion slerp interpolation, implemented by mix function

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This commit is contained in:
Christophe Riccio 2012-12-21 02:21:21 +01:00
parent b5274bfa52
commit 6f22430bbc
1 changed files with 18 additions and 4 deletions
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22
glm/gtc/quaternion.inl
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@ -451,19 +451,33 @@ namespace detail
T const & a T const & a
) )
{ {
detail::tquat<T> z = y;
T cosTheta = dot(x, y); T cosTheta = dot(x, y);
if(glm::abs(cosTheta - T(1)) <= epsilon<T>())
// If cosTheta < 0, the interpolation will take the long way around the sphere.
// To fix this, one quat must be negated.
if (cosTheta < T(0))
{ {
z = -y;
cosTheta = -cosTheta;
}
// Perform a linear interpolation when cosTheta is close to 1 to avoid side effect of sin(angle) becoming a zero denominator
if(cosTheta > T(1) - epsilon<T>())
{
// Linear interpolation
return detail::tquat<T>( return detail::tquat<T>(
mix(x.w, y.w, a),
mix(x.x, y.x, a), mix(x.x, y.x, a),
mix(x.y, y.y, a), mix(x.y, y.y, a),
mix(x.z, y.z, a), mix(x.z, y.z, a));
mix(x.w, y.w, a));
} }
else else
{ {
// Essential Mathematics, page 467
T angle = acos(cosTheta); T angle = acos(cosTheta);
return (glm::sin((T(1) - a) * angle) * x + glm::sin(a * angle) * y) / glm::sin(angle); return (sin((T(1) - a) * angle) * x + sin(a * angle) * z) / sin(angle);
} }
} }