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quaternion: revert elimination of linear case of slerp

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We were generating non-finite results for some cases.
This commit is contained in:
Danny Robson 2019-10-04 17:09:20 +10:00
parent 33dd89e465
commit 9cd6a60134
1 changed files with 12 additions and 10 deletions
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22
quaternion.cpp
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@ -118,17 +118,19 @@ cruft::slerp (quaternion<T> a, quaternion<T> b, T t)
b = -b;
}
// Calculate coefficients.
//
// We previously used a linear interpolation when cosine was almost 1, but
// it tended to trigger assertions for normalised quaternions; feel free to
// change this back, but at this point performance isn't the most prominent
// concern.
T const omega = std::acos (cosine); // extract theta from dot product's cos theta
T const sine = std::sin (omega);
// Calculate coefficients
T p, q;
if (T(0.999999999f) > cosine) {
T omega = std::acos (cosine); // extract theta from dot product's cos theta
T sine = std::sin (omega);
T const p = std::sin ((1 - t) * omega) / sine;
T const q = std::sin ( t * omega) / sine;
p = std::sin ((1 - t) * omega) / sine;
q = std::sin ( t * omega) / sine;
} else {
// Very close, do linear interp (because it's faster)
p = 1 - t;
q = t;
}
return a * p + b * q;
}