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[VRMC_springBone_limit] fix clamp #2832

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75ef36b
fix dot fallback
ousttrue Aug 20, 2026
d4a7a92
ConeLimit
ousttrue Aug 20, 2026
1d840a6
HingeLimit
ousttrue Aug 20, 2026
6924fb9
SphericalLimit
ousttrue Aug 20, 2026
af6847c
clamp when import
ousttrue Aug 20, 2026
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91 changes: 50 additions & 41 deletions Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/Anglelimit.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,61 +6,68 @@ namespace UniGLTF.SpringBoneJobs
public static class Anglelimit
{
public static float3 Apply(
in BlittableJointImmutable logic, in BlittableJointMutable joint,
in quaternion parentRotation, in float3 head, in float3 nextTail)
in BlittableJointImmutable logic,
in BlittableJointMutable joint,
in quaternion parentRotation,
in float3 head,
in float3 nextTail
)
{
var angleSpaceToWorld = anglelimitSpaceToWorld(logic, joint, parentRotation);
var tailDir = math.mul(
math.inverse(angleSpaceToWorld),
math.normalizesafe(nextTail - head)
);

switch (joint.anglelimitType)
{
case AnglelimitTypes.None:
// do nothing
return nextTail;

case AnglelimitTypes.Cone:
{
var angleSpaceToWorld = anglelimitSpaceToWorld(logic, joint, parentRotation);
var tailDir = math.mul(math.inverse(angleSpaceToWorld), math.normalizesafe(nextTail - head));
tailDir = AnglelimitCone.Apply(tailDir, joint.anglelimit1);
return head + math.mul(angleSpaceToWorld, tailDir) * logic.length;
}

case AnglelimitTypes.Hinge:
{
var angleSpaceToWorld = anglelimitSpaceToWorld(logic, joint, parentRotation);
var tailDir = math.mul(math.inverse(angleSpaceToWorld), math.normalizesafe(nextTail - head));
tailDir = AnglelimitHinge.Apply(tailDir, joint.anglelimit1);
return head + math.mul(angleSpaceToWorld, tailDir) * logic.length;
}
tailDir = AnglelimitCone.Apply(tailDir, joint.anglelimit1);
break;

case AnglelimitTypes.Hinge:
tailDir = AnglelimitHinge.Apply(tailDir, joint.anglelimit1);
break;

case AnglelimitTypes.Spherical:
{
var angleSpaceToWorld = anglelimitSpaceToWorld(logic, joint, parentRotation);
var tailDir = math.mul(math.inverse(angleSpaceToWorld), math.normalizesafe(nextTail - head));
tailDir = AnglelimitSpherical.Apply(tailDir, joint.anglelimit1, joint.anglelimit2);
return head + math.mul(angleSpaceToWorld, tailDir) * logic.length;
}
tailDir = AnglelimitSpherical.Apply(
tailDir,
joint.anglelimit1,
joint.anglelimit2
);
break;

default:
throw new System.ArgumentException($"unknown joint.anglelimitType: {joint.anglelimitType}");
throw new System.ArgumentException(
$"unknown joint.anglelimitType: {joint.anglelimitType}"
);
}

return head + math.mul(angleSpaceToWorld, tailDir) * logic.length;
}

/// <param name="nextTail">nextTail(position vector in world space)</param>
/// <returns>tailDir(directionay vector in angle space)</returns>
/// <exception cref="System.NotImplementedException"></exception>
public static quaternion anglelimitSpaceToWorld(in BlittableJointImmutable logic, in BlittableJointMutable joint,
in quaternion parentRotation)
public static quaternion anglelimitSpaceToWorld(
in BlittableJointImmutable logic,
in BlittableJointMutable joint,
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 = 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
math.mul(parentRotation,
math.mul(logic.localRotation,
math.mul(axisRotation,
joint.anglelimitOffset)))
;
return math.mul(
parentRotation,
math.mul(logic.localRotation, math.mul(axisRotation, joint.anglelimitOffset))
);
}

/// <summary>
Expand All @@ -71,20 +78,22 @@ public static quaternion anglelimitSpaceToWorld(in BlittableJointImmutable logic
///
/// TODO: Replace with the appropriate link to the specification later
/// </summary>
public static quaternion getAxisRotation(in float3 to)
public static quaternion getAxisRotation(in float3 boneAxis)
{
// dot(from, to) + 1
var dot1 = to.y + 1f;
// headからtailに向かうベクトルとY+方向との内積
var dot = boneAxis.y;

// Handle the case where from and to are parallel and opposite
if (dot1 < 1e-8f) // dot is approximately -1
if (dot == -1.0)
{
return new quaternion(1f, 0f, 0f, 0f);
// headからtailに向かうベクトルがY-方向の場合、X軸周りに180度回転させた回転を設定する
return new quaternion(1, 0, 0, 0);
}
Comment on lines +86 to +90
else
{
// それ以外の場合、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を設定する
// quaternion(cross(from, to); dot(from, to) + 1).normalized
return math.normalizesafe(new quaternion(boneAxis.z, 0, -boneAxis.x, dot + 1));
}

// General case
// quaternion(cross(from, to); dot(from, to) + 1).normalized
return math.normalizesafe(new quaternion(to.z, 0f, -to.x, dot1));
}
}
}
}
43 changes: 27 additions & 16 deletions Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitCone.cs
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Expand Up @@ -4,30 +4,41 @@ namespace UniGLTF.SpringBoneJobs
{
public static class AnglelimitCone
{
/// <param name="src">AngleLimit空間の方向ベクトル</param>
/// <param name="angleLimit">radius</param>
/// <param name="tailDir">AngleLimit空間の方向ベクトル</param>
/// <param name="limitAngle">radius</param>
/// <returns>AngleLimit空間の方向ベクトル</returns>
public static float3 Apply(in float3 src, float angleLimit)
public static float3 Apply(float3 tailDir, float limitAngle)
{
// tailDirのy要素をjointに設定されたangleの余弦と比較する
var cosAngle = math.cos(angleLimit);
if (src.y >= cosAngle)
{
return src;
}
// angleを0以上π以下に制限する
limitAngle = math.clamp(limitAngle, 0.0f, math.PI);

var tailDir = src;
// tailDirのy要素をlimitに設定されたangleの余弦と比較する
var cosLimitAngle = math.cos(limitAngle);
if (tailDir.y < cosLimitAngle)
{
// x・z要素を、tailDirの正弦とjointに設定されたangleの正弦の比を用いてスケールする
var ratio = math.sqrt((1.0f - cosAngle * cosAngle) / (1.0f - tailDir.y * tailDir.y));
tailDir.x *= ratio;
tailDir.z *= ratio;
var horizontalLengthSquared = 1.0f - tailDir.y * tailDir.y;

if (horizontalLengthSquared == 0.0)

@0b5vr 0b5vr Aug 20, 2026

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SHOULD: 誤差を考慮した比較を行ったほうが良さそうです。three-vrm側はこんな感じです:

https://github.com/pixiv/three-vrm/blob/f6a4d0f34360fda4bbba2c509d66a00da6cac557/packages/three-vrm-springbone/src/VRMSpringBoneLimitCone.ts#L41

{
Comment on lines +20 to +23
// tailDirがy軸負方向の場合、z軸正方向側を選択する
tailDir.x = 0.0f;
tailDir.z = math.sqrt(1.0f - cosLimitAngle * cosLimitAngle);
}
else
{
var scale = math.sqrt(
(1.0f - cosLimitAngle * cosLimitAngle) / horizontalLengthSquared
);
tailDir.x *= scale;
tailDir.z *= scale;
}

// y要素を、jointに設定されたangleの余弦とする
tailDir.y = cosAngle;
// y要素をlimitに設定されたangleの余弦とする
tailDir.y = cosLimitAngle;
}

return tailDir;
}
}
}
}
44 changes: 27 additions & 17 deletions Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitHinge.cs
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Expand Up @@ -4,29 +4,39 @@ namespace UniGLTF.SpringBoneJobs
{
public static class AnglelimitHinge
{
/// <param name="src">AngleLimit空間の方向ベクトル</param>
/// <param name="angleLimit">radius</param>
/// <param name="tailDir">AngleLimit空間の方向ベクトル</param>
/// <param name="limitAngle">radius</param>
/// <returns>AngleLimit空間の方向ベクトル</returns>
public static float3 Apply(in float3 src, float limitAngle)
public static float3 Apply(float3 tailDir, float limitAngle)
{
// x要素を0にし、正規化する
float3 tailDir = src;
tailDir.x = 0.0f;
tailDir = math.normalizesafe(tailDir);
// angleを0以上π以下に制限する
limitAngle = math.clamp(limitAngle, 0.0f, math.PI);

// tailDirのy要素をjointに設定されたangleの余弦と比較する
var cosAngle = math.cos(limitAngle);
if (tailDir.y < cosAngle)
var projectedLengthSquared = tailDir.y * tailDir.y + tailDir.z * tailDir.z;
if (projectedLengthSquared == 0.0f)

@0b5vr 0b5vr Aug 20, 2026

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MAY: こちらも、three-vrmでは、誤差を考慮した比較を行っています。

https://github.com/pixiv/three-vrm/blob/f6a4d0f34360fda4bbba2c509d66a00da6cac557/packages/three-vrm-springbone/src/VRMSpringBoneLimitHinge.ts#L31

{
Comment on lines +15 to 17
// z要素を、tailDirの正弦とjointに設定されたangleの正弦の比を用いてスケールする
var ratio = math.sqrt((1.0f - cosAngle * cosAngle) / (1.0f - tailDir.y * tailDir.y));
tailDir.z *= ratio;

// y要素を、jointに設定されたangleの余弦とする
tailDir.y = cosAngle;
// tailDirがx軸正方向または負方向の場合、Y軸正方向を選択する
tailDir = math.float3(0.0f, 1.0f, 0.0f);
}
else
{
// tailDirをヒンジのYZ平面へ射影する
tailDir =
math.float3(0.0f, tailDir.y, tailDir.z) / math.sqrt(projectedLengthSquared);

// tailDirのy要素をlimitに設定されたangleの余弦と比較する
var cosLimitAngle = math.cos(limitAngle);
if (tailDir.y < cosLimitAngle)
{
var sinLimitAngle = math.sqrt(1.0f - cosLimitAngle * cosLimitAngle);

// tailDirがy軸負方向の場合、z軸正方向側を選択する
var zSign = (tailDir.z < 0.0f) ? -1.0f : 1.0f;
tailDir.y = cosLimitAngle;
tailDir.z = sinLimitAngle * zSign;
Comment on lines +33 to +36
}
}
return tailDir;
}
}
}
}
60 changes: 42 additions & 18 deletions Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitSpherical.cs
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Original file line number Diff line number Diff line change
@@ -1,37 +1,61 @@
using System;
using Unity.Mathematics;
using UnityEngine;
Comment on lines +1 to +3

namespace UniGLTF.SpringBoneJobs
{
public static class AnglelimitSpherical
{
/// <param name="tailDir">AngleLimit空間の方向ベクトル</param>
/// <param name="limitAnglePhi">radius</param>
/// <param name="limitAngleTheta">radius</param>
/// <param name="limitPitch">radius</param>
/// <param name="limitYaw">radius</param>
/// <returns>AngleLimit空間の方向ベクトル</returns>
public static float3 Apply(in float3 tailDir, float limitAnglePhi, float limitAngleTheta)
public static float3 Apply(float3 tailDir, float limitPitch, float limitYaw)
{
// tailDirのphi・thetaを計算する
var phi = math.atan2(tailDir.z, tailDir.y);
var theta = math.asin(tailDir.x);
// pitchを0以上π以下、yawを0以上π/2以下に制限する
limitPitch = math.clamp(limitPitch, 0.0f, math.PI);
limitYaw = math.clamp(limitYaw, 0.0f, math.PI / 2.0f);

// phi・thetaをjointに設定されたphi・thetaを用いて制限する
// var isLimited = false;
if (math.abs(phi) > limitAnglePhi)
// tailDirのpitch・yawを計算する
float pitch;
if (tailDir.y == -1.0)

@0b5vr 0b5vr Aug 20, 2026

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three-vrmの実装ではこうなってます:
https://github.com/pixiv/three-vrm/blob/f6a4d0f34360fda4bbba2c509d66a00da6cac557/packages/three-vrm-springbone/src/VRMSpringBoneLimitSpherical.ts#L38

{
// tailDirがy軸負方向の場合、Z軸正方向側の境界を選択するため、pitchをπとする
pitch = math.PI;
}
else if (math.abs(tailDir.x) == 1.0f)

@0b5vr 0b5vr Aug 20, 2026

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[MAY] こちらもthree-vrmではEPSILONを入れた特異点処理としています。こちらは誤差付きで比較しなくてもそこまで問題にならないかも

https://github.com/pixiv/three-vrm/blob/f6a4d0f34360fda4bbba2c509d66a00da6cac557/packages/three-vrm-springbone/src/VRMSpringBoneLimitSpherical.ts#L41

{
// tailDirがx軸正方向または負方向の場合、pitchを0とする
pitch = 0.0f;
}
else
{
pitch = math.atan2(tailDir.z, tailDir.y);
}
var yaw = math.asin(tailDir.x);

@0b5vr 0b5vr Aug 20, 2026

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SHOULD: tailDir.x の範囲が [-1.0, 1.0] の外に行くと、math.asinが NaN を返し得ます。おそらく、-1, 1でclampしたほうが良いです。


// pitchをlimitに設定されたpitchを用いて制限する
if (math.abs(pitch) > limitPitch)
{
// isLimited = true;
phi = limitAnglePhi * math.sign(phi);
pitch = limitPitch * math.sign(pitch);
}

// thetaをjointに設定されたthetaを用いて制限する
if (math.abs(theta) > limitAngleTheta)
// yawをlimitに設定されたyawを用いて制限する
if (math.abs(yaw) > limitYaw)
{
// isLimited = true;
theta = limitAngleTheta * math.sign(theta);
// isLimited = true;
yaw = limitYaw * math.sign(yaw);
}

// tailDirをphi・thetaを用いて再計算する
var cos_theta = math.cos(theta);
return new float3(math.sin(theta), cos_theta * math.cos(phi), cos_theta * math.sin(phi));
// tailDirをpitch・yawを用いて再計算する
tailDir = math.float3(
math.sin(yaw),
math.cos(yaw) * math.cos(pitch),
math.cos(yaw) * math.sin(pitch)
);

return tailDir;
}
}
}
}
11 changes: 5 additions & 6 deletions Packages/VRM10/Runtime/IO/Vrm10Importer.cs
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Original file line number Diff line number Diff line change
@@ -1,11 +1,10 @@
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Threading.Tasks;
using UniGLTF;
using UniGLTF.Extensions.VRMC_springBone_limit;
using UniGLTF.Utils;
using Unity.Mathematics;
using UnityEngine;

namespace UniVRM10
Expand Down Expand Up @@ -655,20 +654,20 @@ async Task LoadSpringBoneAsync(IAwaitCaller awaitCaller, Vrm10Instance controlle
{
joint.m_anglelimitType = UniGLTF.SpringBoneJobs.AnglelimitTypes.Cone;
joint.m_limitSpaceOffset = QuaternionFromFloat4(cone.Rotation);
joint.m_pitch = cone.Angle.GetValueOrDefault();
joint.m_pitch = math.clamp(cone.Angle.GetValueOrDefault(), 0.0f, math.PI);
}
else if (extensionSpringBoneLimit.Limit.Hinge is UniGLTF.Extensions.VRMC_springBone_limit.HingeLimit hinge)
{
joint.m_anglelimitType = UniGLTF.SpringBoneJobs.AnglelimitTypes.Hinge;
joint.m_limitSpaceOffset = QuaternionFromFloat4(hinge.Rotation);
joint.m_pitch = hinge.Angle.GetValueOrDefault();
joint.m_pitch = math.clamp(hinge.Angle.GetValueOrDefault(), 0.0f, math.PI);
}
else if (extensionSpringBoneLimit.Limit.Spherical is UniGLTF.Extensions.VRMC_springBone_limit.SphericalLimit spherical)
{
joint.m_anglelimitType = UniGLTF.SpringBoneJobs.AnglelimitTypes.Spherical;
joint.m_limitSpaceOffset = QuaternionFromFloat4(spherical.Rotation);
joint.m_pitch = spherical.Pitch.GetValueOrDefault();
joint.m_yaw = spherical.Yaw.GetValueOrDefault();
joint.m_pitch = math.clamp(spherical.Pitch.GetValueOrDefault(), 0.0f, math.PI);
joint.m_yaw = math.clamp(spherical.Yaw.GetValueOrDefault(), 0.0f, math.PI / 2);
}
}

Expand Down
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