FBX import: add a setting to define a custom animation offset value, in frames.

In theory, Blender's animations start at frame 1, while FBX ones start at t0,
but looks like users need tweaking ability here too! ;)

io_scene_fbx/__init__.py

@@ -21,7 +21,7 @@
 bl_info = {
     "name": "FBX format",
     "author": "Campbell Barton, Bastien Montagne, Jens Restemeier",
-    "version": (3, 3, 5),
+    "version": (3, 3, 6),
     "blender": (2, 74, 0),
     "location": "File > Import-Export",
     "description": "FBX IO meshes, UV's, vertex colors, materials, textures, cameras, lamps and actions",
@@ -108,6 +108,12 @@ class ImportFBX(bpy.types.Operator, ImportHelper, IOFBXOrientationHelper):
             default=0.0,
             )
 
+    anim_offset = FloatProperty(
+            name="Animation Offset",
+            description="Offset to apply to animation during import, in frames",
+            default=1.0,
+            )
+
     use_custom_props = BoolProperty(
             name="Import User Properties",
             description="Import user properties as custom properties",
@@ -179,6 +185,8 @@ class ImportFBX(bpy.types.Operator, ImportHelper, IOFBXOrientationHelper):
         # layout.prop(self, "use_alpha_decals")
         layout.prop(self, "decal_offset")
 
+        layout.prop(self, "anim_offset")
+
         layout.prop(self, "use_custom_props")
         sub = layout.row()
         sub.enabled = self.use_custom_props

io_scene_fbx/fbx_utils.py

@@ -1225,6 +1225,7 @@ FBXImportSettings = namedtuple("FBXImportSettings", (
     "bake_space_transform", "global_matrix_inv", "global_matrix_inv_transposed",
     "use_cycles", "use_image_search",
     "use_alpha_decals", "decal_offset",
+    "anim_offset",
     "use_custom_props", "use_custom_props_enum_as_string",
     "cycles_material_wrap_map", "image_cache",
     "ignore_leaf_bones", "force_connect_children", "automatic_bone_orientation", "bone_correction_matrix",

io_scene_fbx/import_fbx.py

@@ -539,7 +539,7 @@ def blen_read_animations_curves_iter(fbx_curves, blen_start_offset, fbx_start_of
         yield (curr_blenkframe, curr_values)
 
 
-def blen_read_animations_action_item(action, item, cnodes, fps):
+def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset):
     """
     'Bake' loc/rot/scale into the action,
     taking any pre_ and post_ matrix into account to transform from fbx into blender space.
@@ -587,8 +587,7 @@ def blen_read_animations_action_item(action, item, cnodes, fps):
                    for prop, nbr_channels, grpname in props for channel in range(nbr_channels)]
 
     if isinstance(item, ShapeKey):
-        # We assume for now blen init point is frame 1.0, while FBX ktime init point is 0.
-        for frame, values in blen_read_animations_curves_iter(fbx_curves, 1.0, 0, fps):
+        for frame, values in blen_read_animations_curves_iter(fbx_curves, anim_offset, 0, fps):
             value = 0.0
             for v, (fbxprop, channel, _fbx_acdata) in values:
                 assert(fbxprop == b'DeformPercent')
@@ -610,8 +609,7 @@ def blen_read_animations_action_item(action, item, cnodes, fps):
         # Pre-compute inverted local rest matrix of the bone, if relevant.
         restmat_inv = item.get_bind_matrix().inverted_safe() if item.is_bone else None
 
-        # We assume for now blen init point is frame 1.0, while FBX ktime init point is 0.
-        for frame, values in blen_read_animations_curves_iter(fbx_curves, 1.0, 0, fps):
+        for frame, values in blen_read_animations_curves_iter(fbx_curves, anim_offset, 0, fps):
             for v, (fbxprop, channel, _fbx_acdata) in values:
                 if fbxprop == b'Lcl Translation':
                     transform_data.loc[channel] = v
@@ -655,7 +653,7 @@ def blen_read_animations_action_item(action, item, cnodes, fps):
         fc.update()
 
 
-def blen_read_animations(fbx_tmpl_astack, fbx_tmpl_alayer, stacks, scene):
+def blen_read_animations(fbx_tmpl_astack, fbx_tmpl_alayer, stacks, scene, anim_offset):
     """
     Recreate an action per stack/layer/object combinations.
     Only the first found action is linked to objects, more complex setups are not handled,
@@ -688,7 +686,7 @@ def blen_read_animations(fbx_tmpl_astack, fbx_tmpl_alayer, stacks, scene):
                 if not id_data.animation_data.action:
                     id_data.animation_data.action = action
                 # And actually populate the action!
-                blen_read_animations_action_item(action, item, cnodes, scene.render.fps)
+                blen_read_animations_action_item(action, item, cnodes, scene.render.fps, anim_offset)
 
 
 # ----
@@ -2076,6 +2074,7 @@ def load(operator, context, filepath="",
          use_image_search=False,
          use_alpha_decals=False,
          decal_offset=0.0,
+         anim_offset=1.0,
          use_custom_props=True,
          use_custom_props_enum_as_string=True,
          ignore_leaf_bones=False,
@@ -2202,6 +2201,7 @@ def load(operator, context, filepath="",
         bake_space_transform, global_matrix_inv, global_matrix_inv_transposed,
         use_cycles, use_image_search,
         use_alpha_decals, decal_offset,
+        anim_offset,
         use_custom_props, use_custom_props_enum_as_string,
         cycles_material_wrap_map, image_cache,
         ignore_leaf_bones, force_connect_children, automatic_bone_orientation, bone_correction_matrix,
@@ -2688,7 +2688,7 @@ def load(operator, context, filepath="",
                 curvenodes[acn_uuid][ac_uuid] = (fbx_acitem, channel)
 
         # And now that we have sorted all this, apply animations!
-        blen_read_animations(fbx_tmpl_astack, fbx_tmpl_alayer, stacks, scene)
+        blen_read_animations(fbx_tmpl_astack, fbx_tmpl_alayer, stacks, scene, settings.anim_offset)
 
     _(); del _