patch from Doug Perkowski

from Doug:

Most applications aren't very strict with the bind pose because they support different bind poses for different meshes.  Ogre requires a single bind pose for all meshes, which makes things a lot more difficult. 

The changes are where the BindPose is defined (which is pretty much ignored by most applications, but you seemed to have added it for XNA), and the skin deformer.  In both cases, global transforms for bones were not correctly being exported.  I set global transforms for the bones equal to (my_bone.fbxArm.matrixWorld * my_bone.restMatrix) * mtx4_z90.  That  appears to do the trick for me, though I can't say I fully understand how the terms are derived.

I've tested kngcalvn_fbx_test_new.fbx and our sample file in Maya & our FBX importer, and both work with the changes.

1 files changed, 21 insertions, 13 deletions

diff --git a/io_scene_fbx/export_fbx.py b/io_scene_fbx/export_fbx.py
index a33cf78f..73e1b195 100644
--- a/io_scene_fbx/export_fbx.py
+++ b/io_scene_fbx/export_fbx.py
@@ -686,7 +686,11 @@ def save_single(operator, scene, filepath="",
 
         #~ poseMatrix = write_object_props(my_bone.blenBone, None, None, my_bone.fbxArm.parRelMatrix())[3]
         poseMatrix = write_object_props(my_bone.blenBone, pose_bone=my_bone.getPoseBone())[3]  # dont apply bone matrices anymore
-        pose_items.append((my_bone.fbxName, poseMatrix))
+
+        # Use the same calculation as in write_sub_deformer_skin to compute the global
+        # transform of the bone for the bind pose.
+        global_matrix_bone = (my_bone.fbxArm.matrixWorld * my_bone.restMatrix) * mtx4_z90
+        pose_items.append((my_bone.fbxName, global_matrix_bone))
 
         # fw('\n\t\t\tProperty: "Size", "double", "",%.6f' % ((my_bone.blenData.head['ARMATURESPACE'] - my_bone.blenData.tail['ARMATURESPACE']) * my_bone.fbxArm.parRelMatrix()).length)
         fw('\n\t\t\tProperty: "Size", "double", "",1')
@@ -1331,19 +1335,19 @@ def save_single(operator, scene, filepath="",
                 fw(',%.8f' % vg[1])
             i += 1
 
-        if my_mesh.fbxParent:
-            # TODO FIXME, this case is broken in some cases. skinned meshes just shouldnt have parents where possible!
-            m = (my_mesh.matrixWorld.inverted() * my_bone.fbxArm.matrixWorld.copy() * my_bone.restMatrix) * mtx4_z90
-        else:
-            # Yes! this is it...  - but dosnt work when the mesh is a.
-            m = (my_mesh.matrixWorld.inverted() * my_bone.fbxArm.matrixWorld.copy() * my_bone.restMatrix) * mtx4_z90
+        # Set TransformLink to the global transform of the bone and Transform
+        # equal to the mesh's transform in bone space.
+        # http://area.autodesk.com/forum/autodesk-fbx/fbx-sdk/why-the-values-return-by-fbxcluster-gettransformmatrix-x-not-same-with-the-value-in-ascii-fbx-file/
 
-        #m = mtx4_z90 * my_bone.restMatrix
-        matstr = mat4x4str(m)
-        matstr_i = mat4x4str(m.inverted())
+        global_bone_matrix = (my_bone.fbxArm.matrixWorld * my_bone.restMatrix) * mtx4_z90
+        global_mesh_matrix = my_mesh.matrixWorld
+        transform_matrix = (global_bone_matrix.inverted() * global_mesh_matrix)
 
-        fw('\n\t\tTransform: %s' % matstr_i)  # THIS IS __NOT__ THE GLOBAL MATRIX AS DOCUMENTED :/
-        fw('\n\t\tTransformLink: %s' % matstr)
+        global_bone_matrix_string = mat4x4str(global_bone_matrix )
+        transform_matrix_string = mat4x4str(transform_matrix )
+
+        fw('\n\t\tTransform: %s' % transform_matrix_string)
+        fw('\n\t\tTransformLink: %s' % global_bone_matrix_string)
         fw('\n\t}')
 
     def write_mesh(my_mesh):
@@ -1367,7 +1371,11 @@ def save_single(operator, scene, filepath="",
         me_faces = me.tessfaces[:]
 
         poseMatrix = write_object_props(my_mesh.blenObject, None, my_mesh.parRelMatrix())[3]
-        pose_items.append((my_mesh.fbxName, poseMatrix))
+
+        # Calculate the global transform for the mesh in the bind pose the same way we do
+        # in write_sub_deformer_skin
+        globalMeshBindPose = my_mesh.matrixWorld * mtx4_z90
+        pose_items.append((my_mesh.fbxName, globalMeshBindPose))
 
         if do_shapekeys:
             for kb in my_mesh.blenObject.data.shape_keys.key_blocks[1:]: