Attempt to fix FBX scaling issues in a different way.

Now we offer choices to apply everything in transform, store everyting
in FBX scale, or mix both solutions (taking custom export scale and unit
scale into account here).

This change a bit default behavior, and hopefully will allow to find at
least one options working correctly with a given 'other tool' importer.

This may address T51704 and T50159.

1 files changed, 26 insertions, 12 deletions

diff --git a/io_scene_fbx/export_fbx_bin.py b/io_scene_fbx/export_fbx_bin.py
index 70d149bf..9797b117 100644
--- a/io_scene_fbx/export_fbx_bin.py
+++ b/io_scene_fbx/export_fbx_bin.py
@@ -2673,15 +2673,16 @@ def fbx_header_elements(root, scene_data, time=None):
 
     props = elem_properties(global_settings)
     up_axis, front_axis, coord_axis = RIGHT_HAND_AXES[scene_data.settings.to_axes]
-    # DO NOT take into account global scale here! That setting is applied to object transformations during export
-    # (in other words, this is pure blender-exporter feature, and has nothing to do with FBX data).
-    if scene_data.settings.apply_unit_scale:
-        # Unit scaling is applied to objects' scale, so our unit is effectively FBX one (centimeter).
-        scale_factor_org = 1.0
-        scale_factor = 1.0 / units_blender_to_fbx_factor(scene)
-    else:
-        scale_factor_org = units_blender_to_fbx_factor(scene)
-        scale_factor = scale_factor_org
+    #~ # DO NOT take into account global scale here! That setting is applied to object transformations during export
+    #~ # (in other words, this is pure blender-exporter feature, and has nothing to do with FBX data).
+    #~ if scene_data.settings.apply_unit_scale:
+        #~ # Unit scaling is applied to objects' scale, so our unit is effectively FBX one (centimeter).
+        #~ scale_factor_org = 1.0
+        #~ scale_factor = 1.0 / units_blender_to_fbx_factor(scene)
+    #~ else:
+        #~ scale_factor_org = units_blender_to_fbx_factor(scene)
+        #~ scale_factor = scale_factor_org
+    scale_factor = scale_factor_org = scene_data.settings.unit_scale
     elem_props_set(props, "p_integer", b"UpAxis", up_axis[0])
     elem_props_set(props, "p_integer", b"UpAxisSign", up_axis[1])
     elem_props_set(props, "p_integer", b"FrontAxis", front_axis[0])
@@ -2867,6 +2868,8 @@ def fbx_takes_elements(root, scene_data):
 def save_single(operator, scene, filepath="",
                 global_matrix=Matrix(),
                 apply_unit_scale=False,
+                global_scale=1.0,
+                apply_scale_options='FBX_SCALE_NONE',
                 axis_up="Z",
                 axis_forward="Y",
                 context_objects=None,
@@ -2905,8 +2908,19 @@ def save_single(operator, scene, filepath="",
     if 'OTHER' in object_types:
         object_types |= BLENDER_OTHER_OBJECT_TYPES
 
-    if apply_unit_scale:
-        global_matrix = global_matrix * Matrix.Scale(units_blender_to_fbx_factor(scene), 4)
+    # Default Blender unit is equivalent to meter, while FBX one is centimeter...
+    unit_scale = units_blender_to_fbx_factor(scene) if apply_unit_scale else 100.0
+    if apply_scale_options == 'FBX_SCALE_NONE':
+        global_matrix = Matrix.Scale(unit_scale * global_scale, 4) * global_matrix
+        unit_scale = 1.0
+    elif apply_scale_options == 'FBX_SCALE_UNITS':
+        global_matrix = Matrix.Scale(global_scale, 4) * global_matrix
+    elif apply_scale_options == 'FBX_SCALE_CUSTOM':
+        global_matrix = Matrix.Scale(unit_scale, 4) * global_matrix
+        unit_scale = global_scale
+    else: # if apply_scale_options == 'FBX_SCALE_ALL':
+        unit_scale = global_scale * unit_scale
+
     global_scale = global_matrix.median_scale
     global_matrix_inv = global_matrix.inverted()
     # For transforming mesh normals.
@@ -2941,7 +2955,7 @@ def save_single(operator, scene, filepath="",
     )
 
     settings = FBXExportSettings(
-        operator.report, (axis_up, axis_forward), global_matrix, global_scale, apply_unit_scale,
+        operator.report, (axis_up, axis_forward), global_matrix, global_scale, apply_unit_scale, unit_scale,
         bake_space_transform, global_matrix_inv, global_matrix_inv_transposed,
         context_objects, object_types, use_mesh_modifiers, use_mesh_modifiers_render,
         mesh_smooth_type, use_mesh_edges, use_tspace,