From dc9de498d681b235eac7418d3467d9b5ace69e4a Mon Sep 17 00:00:00 2001
From: ousttrue <ousttrue@gmail.com>
Date: Thu, 3 Sep 2026 10:20:48 +0900
Subject: [PATCH] =?UTF-8?q?SINGULARITY=5FEPSILON=20=E7=89=B9=E7=95=B0?=
 =?UTF-8?q?=E7=82=B9=5F=E9=96=BE=E5=80=A4?=
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---
 .../Runtime/SpringBoneJobs/Anglelimit/Anglelimit.cs       | 5 ++++-
 .../Runtime/SpringBoneJobs/Anglelimit/AnglelimitCone.cs   | 2 +-
 .../Runtime/SpringBoneJobs/Anglelimit/AnglelimitHinge.cs  | 4 ++--
 .../SpringBoneJobs/Anglelimit/AnglelimitSpherical.cs      | 8 +++-----
 4 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/Anglelimit.cs b/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/Anglelimit.cs
index fd58c3d23..7a39c62ca 100644
--- a/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/Anglelimit.cs
+++ b/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/Anglelimit.cs
@@ -1,3 +1,4 @@
+using System;
 using UniGLTF.SpringBoneJobs.Blittables;
 using Unity.Mathematics;
 
@@ -5,6 +6,8 @@ namespace UniGLTF.SpringBoneJobs
 {
     public static class Anglelimit
     {
+        public static readonly float SINGULARITY_EPSILON = MathF.Sqrt(float.Epsilon);
+
         public static float3 Apply(
             in BlittableJointImmutable logic,
             in BlittableJointMutable joint,
@@ -83,7 +86,7 @@ namespace UniGLTF.SpringBoneJobs
             // headからtailに向かうベクトルとY+方向との内積
             var dot = boneAxis.y;
 
-            if (dot == -1.0)
+            if (dot <= -1f + SINGULARITY_EPSILON)
             {
                 // 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);
diff --git a/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitCone.cs b/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitCone.cs
index 6fe2a8557..bd530af4e 100644
--- a/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitCone.cs
+++ b/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitCone.cs
@@ -19,7 +19,7 @@ namespace UniGLTF.SpringBoneJobs
                 // 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 horizontalLengthSquared = 1.0f - tailDir.y * tailDir.y;
 
-                if (horizontalLengthSquared <= 1e-8f)
+                if (horizontalLengthSquared <= Anglelimit.SINGULARITY_EPSILON)
                 {
                     // 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;
diff --git a/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitHinge.cs b/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitHinge.cs
index 6010d94be..9e4fcf387 100644
--- a/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitHinge.cs
+++ b/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitHinge.cs
@@ -13,7 +13,7 @@ namespace UniGLTF.SpringBoneJobs
             limitAngle = math.clamp(limitAngle, 0.0f, math.PI);
 
             var projectedLengthSquared = tailDir.y * tailDir.y + tailDir.z * tailDir.z;
-            if (projectedLengthSquared == 0.0f)
+            if (projectedLengthSquared <= Anglelimit.SINGULARITY_EPSILON)
             {
                 // 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);
@@ -30,7 +30,7 @@ namespace UniGLTF.SpringBoneJobs
                 {
                     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
+                    // zの符号を維持し、z==0 の場合は 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;
diff --git a/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitSpherical.cs b/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitSpherical.cs
index 06090da62..61cdfc2b3 100644
--- a/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitSpherical.cs
+++ b/Packages/UniGLTF/Runtime/SpringBoneJobs/Anglelimit/AnglelimitSpherical.cs
@@ -1,6 +1,4 @@
-using System;
 using Unity.Mathematics;
-using UnityEngine;
 
 namespace UniGLTF.SpringBoneJobs
 {
@@ -18,12 +16,12 @@ namespace UniGLTF.SpringBoneJobs
 
             // tailDirのpitch・yawを計算する
             float pitch;
-            if (tailDir.y == -1.0)
+            if (tailDir.y <= -1.0 + Anglelimit.SINGULARITY_EPSILON)
             {
                 // 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)
+            else if (math.abs(tailDir.x) <= 1.0f - Anglelimit.SINGULARITY_EPSILON)
             {
                 // 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;
@@ -32,7 +30,7 @@ namespace UniGLTF.SpringBoneJobs
             {
                 pitch = math.atan2(tailDir.z, tailDir.y);
             }
-            var yaw = math.asin(tailDir.x);
+            var yaw = math.asin(math.clamp(tailDir.x, -1f, 1f));
 
             // pitchをlimitに設定されたpitchを用いて制限する
             if (math.abs(pitch) > limitPitch)