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Merge branch 'master' into Custom-Normals-Import

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ousttrue 2026-01-16 14:54:52 +09:00 committed by GitHub
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35
Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/Anglelimit.cs
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@ -52,7 +52,7 @@ namespace UniGLTF.SpringBoneJobs
in quaternion parentRotation)
{
// Y+方向からjointのheadからtailに向かうベクトルへの最小回転
var axisRotation = fromToQuaternion(new float3(0, 1, 0), logic.boneAxis);
var axisRotation = getAxisRotation(logic.boneAxis);
// limitのローカル空間をワールド空間に写像する回転
return
@ -63,29 +63,28 @@ namespace UniGLTF.SpringBoneJobs
;
}
// https://discussions.unity.com/t/unity-mathematics-equivalent-to-quaternion-fromtorotation/237459
public static quaternion fromToQuaternion(in float3 from, in float3 to)
/// <summary>
/// Y軸正方向から `to` への回転を表すクォータニオンを計算して返す。
/// `to` は正規化されていると仮定する。
///
/// See: https://github.com/0b5vr/vrm-specification/blob/75fbd48a7cb1d7250fa955838af6140e9c84844c/specification/VRMC_springBone_limit-1.0/README.ja.md#rotation-1
///
/// TODO: Replace with the appropriate link to the specification later
/// </summary>
public static quaternion getAxisRotation(in float3 to)
{
var fromNorm = math.normalize(from);
var toNorm = math.normalize(to);
var dot = math.dot(fromNorm, toNorm);
// dot(from, to) + 1
var dot1 = to.y + 1f;
// Handle the case where from and to are parallel but opposite
if (math.abs(dot + 1f) < 1e-6f) // dot is approximately -1
// Handle the case where from and to are parallel and opposite
if (dot1 < 1e-8f) // dot is approximately -1
{
// Find a perpendicular axis
var perpAxis = math.abs(fromNorm.x) > math.abs(fromNorm.z)
? new float3(-fromNorm.y, fromNorm.x, 0f)
: new float3(0f, -fromNorm.z, fromNorm.y);
return quaternion.AxisAngle(math.normalize(perpAxis), math.PI);
return new quaternion(1f, 0f, 0f, 0f);
}
// General case
return quaternion.AxisAngle(
angle: math.acos(math.clamp(dot, -1f, 1f)),
axis: math.normalize(math.cross(fromNorm, toNorm))
);
// quaternion(cross(from, to); dot(from, to) + 1).normalized
return math.normalize(new quaternion(to.z, 0f, -to.x, dot1));
}
}
}