Question by z3nth10n · Sep 12, 2020 at 05:47 AM · c#mesh bones skinned mesh renderer

Some submeshes of my gameobject dissapears when I set the bindposes

Well, I'm trying to animate some Source models imported into Unity3D using this Unity-Source-Tools library:

https://github.com/lewa-j/Unity-Source-Tools

To animate a Mesh generated by this tool I need to create a SkinnedMeshRenderer replacing the MeshRenderer and the MeshFilter components, so I created this method:

     private static void ReplaceRenderer(this GameObject obj, SourceStudioModelv2 model)
     {
         if (obj.GetComponent<SkinnedMeshRenderer>() != null)
             return;

         var mesh = Object.Instantiate(obj.GetComponent<MeshFilter>().sharedMesh);

         const bool debugPoses = true;
         const bool useNativePoses = true;

         var nativeBuilder = debugPoses ? new StringBuilder($"Native Matrix\n{new string('=', 10)}\n") : null;
         var unityBuilder = debugPoses ? new StringBuilder($"Unity Matrix\n{new string('=', 10)}\n") : null;

         var nativeMatrix = model.GetBindPosesFromModel(nativeBuilder).ToArray();
         var unityMatrix = obj.transform.GetBindPoses(model.Bones, unityBuilder).ToArray();

         if (debugPoses)
         {
             Debug.Log(nativeBuilder.ToString());
             Debug.Log(unityBuilder.ToString());
         }

         var matrix = useNativePoses
             ? nativeMatrix
             : unityMatrix;

         mesh.bindposes = matrix;

         Object.Destroy(obj.GetComponent<MeshFilter>());
         Object.Destroy(obj.GetComponent<MeshRenderer>());

         var skinned = obj.AddComponent<SkinnedMeshRenderer>();

         skinned.sharedMesh = mesh;
         skinned.rootBone = obj.transform;
         skinned.bones = model.Bones;
     }

As you can see, I'm creating two bind poses, because one of them is created from this part of the code: https://github.com/lewa-j/Unity-Source-Tools/blob/c5469deb1d630c1582c940ff3cdb0f69fc55eda3/Assets/Code/Read/SourceStudioModel.cs#L724-L728

And this is how I create the bindposes:

Native Poses

     private static IEnumerable<Matrix4x4> GetBindPosesFromModel(this SourceStudioModelv2 model, StringBuilder sb = null)
     {
         for (var i = 0; i < model.MdlBones.Length; i++)
         {
             var mdlBone = model.MdlBones[i];
             // From: https://stackoverflow.com/a/49268287/3286975
             var matrix = (new Matrix4x4(
                 new Vector4(mdlBone.PoseToBone[0], mdlBone.PoseToBone[1], mdlBone.PoseToBone[2],
                     mdlBone.PoseToBone[3]),
                 new Vector4(mdlBone.PoseToBone[4], mdlBone.PoseToBone[5], mdlBone.PoseToBone[6],
                     mdlBone.PoseToBone[7]),
                 new Vector4(mdlBone.PoseToBone[8], mdlBone.PoseToBone[9], mdlBone.PoseToBone[10],
                     mdlBone.PoseToBone[11]),
                 new Vector4(0, 0, 0, 1)
             )).transpose;
             sb?.AppendLine($"{i}: {matrix.ToString("F2")}");
             yield return matrix;
         }
     }

Unity Poses

     private static IEnumerable<Matrix4x4> GetBindPoses(this Transform transform, Transform[] bones, StringBuilder sb = null)
     {
         for (var i = 0; i < bones.Length; i++)
         {
             var bone = bones[i];
             var matrix = bone.worldToLocalMatrix * transform.localToWorldMatrix;
             sb?.AppendLine($"{i}: {matrix.ToString("F2")}");
             yield return matrix;
         }
     }

And these are the values that each of them gives to me: