fix: bindpose optimization may break mesh with bones with scale zero

anatawa12 · Oct 17, 2023 · 82b7648 · 82b7648
1 parent 930aeda
commit 82b7648
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Showing 2 changed files with 29 additions and 2 deletions.
diff --git a/Editor/Math/Matrix3x3.cs b/Editor/Math/Matrix3x3.cs
@@ -13,6 +13,10 @@ struct Matrix3x3 : IEquatable<Matrix3x3>
         public static Matrix3x3 zero = new Matrix3x3(0, 0, 0, 0, 0, 0, 0, 0, 0);
         public static Matrix3x3 identity = new Matrix3x3(1, 0, 0, 0, 1, 0, 0, 0, 1);
 
+        public float determinant =>
+            (m00 * m11 * m22) + (m01 * m12 * m20) + (m02 * m10 * m21)
+            - (m00 * m12 * m21) - (m01 * m10 * m22) - (m02 * m11 * m20);
+
         // @formatter:off
         public float m00;
         public float m10;

diff --git a/Editor/Processors/MergeBoneProcessor.cs b/Editor/Processors/MergeBoneProcessor.cs
@@ -123,7 +123,7 @@ private void DoBoneMap2(MeshInfo2 meshInfo2, Dictionary<Transform, Transform> me
                 else
                 {
                     // we assume fist bone we find is the most natural bone.
-                    if (!primaryBones.ContainsKey(bone.Transform))
+                    if (!primaryBones.ContainsKey(bone.Transform) && ValidBindPose(bone.Bindpose))
                         primaryBones.Add(bone.Transform, bone);
                 }
             }
@@ -161,7 +161,7 @@ private void DoBoneMap2(MeshInfo2 meshInfo2, Dictionary<Transform, Transform> me
                 vertex.Tangent = new Vector4(tangentVec3.x, tangentVec3.y, tangentVec3.z, vertex.Tangent.w);
                 foreach (var frames in vertex.BlendShapes.Values)
                 {
-                for (var i = 0; i < frames.Length; i++)
+                    for (var i = 0; i < frames.Length; i++)
                     {
                         var frame = frames[i];
                         frames[i] = new Vertex.BlendShapeFrame(
@@ -204,6 +204,29 @@ private void DoBoneMap2(MeshInfo2 meshInfo2, Dictionary<Transform, Transform> me
             }
         }
 
+        private bool ValidBindPose(Matrix4x4 matrix)
+        {
+            const float SMALL = 0.001f;
+            const float BIG = 10000;
+
+            // if scaling part of bindpose is too small or too big, it can lead to invalid bind pose optimization
+            var scaling = Mathf.Abs(new Matrix3x3(matrix).determinant);
+
+            if (float.IsInfinity(scaling)) return false;
+            if (float.IsNaN(scaling)) return false;
+            if (scaling < SMALL) return false;
+            if (scaling > BIG) return false;
+
+            // if offset part of bindpose is too big, it may lead to invalid bind pose optimization
+
+            var offset = matrix.offset;
+            if (Mathf.Abs(offset.x) > BIG) return false;
+            if (Mathf.Abs(offset.y) > BIG) return false;
+            if (Mathf.Abs(offset.z) > BIG) return false;
+
+            return true;
+        }
+
         private readonly struct BoneUniqKey : IEquatable<BoneUniqKey>
         {
             private readonly Matrix4x4 _bindPoseInfo;