glTF importer: fix regression for skinned mesh normals not being renormalized

1 files changed, 6 insertions, 0 deletions

diff --git a/io_scene_gltf2/blender/imp/gltf2_blender_mesh.py b/io_scene_gltf2/blender/imp/gltf2_blender_mesh.py
index 175bc920..e393eb86 100755
--- a/io_scene_gltf2/blender/imp/gltf2_blender_mesh.py
+++ b/io_scene_gltf2/blender/imp/gltf2_blender_mesh.py
@@ -540,6 +540,7 @@ def skin_into_bind_pose(gltf, skin_idx, vert_joints, vert_weights, locs, vert_no
     if len(vert_normals) != 0:
         vert_normals[:] = mul_mats_vecs(skinning_mats_3x3, vert_normals)
         # Don't translate normals!
+        normalize_vecs(vert_normals)
 
 
 def mul_mats_vecs(mats, vecs):
@@ -547,6 +548,11 @@ def mul_mats_vecs(mats, vecs):
     return np.matmul(mats, vecs.reshape(len(vecs), 3, 1)).reshape(len(vecs), 3)
 
 
+def normalize_vecs(vectors):
+    norms = np.linalg.norm(vectors, axis=1, keepdims=True)
+    np.divide(vectors, norms, out=vectors, where=norms != 0)
+
+
 def merge_duplicate_verts(vert_locs, vert_normals, vert_joints, vert_weights, sk_vert_locs, loop_vidxs, edge_vidxs):
     # This function attempts to invert the splitting done when exporting to
     # glTF. Welds together verts with the same per-vert data (but possibly