FBX IO: add support for exporting nodal shaders.

Getting textures to work was a bit tricky, since we basically have no
more texture IDs in modern shaders (they are mere nodes).

Modified specular conversion to be quadratic (between FBX Phong exponent
to Pricipled specular factor).

Also fixed several issues in both importers and exporters.

And cleaned up ugly usage of 'mat' short name for materials in exporter
(mat is reserved for matrix in Blneder code in general, 'ma' is short
for material).

1 files changed, 12 insertions, 9 deletions

diff --git a/io_scene_fbx/import_fbx.py b/io_scene_fbx/import_fbx.py
index 579c57ae..353a027f 100644
--- a/io_scene_fbx/import_fbx.py
+++ b/io_scene_fbx/import_fbx.py
@@ -1317,6 +1317,7 @@ def blen_read_shape(fbx_tmpl, fbx_sdata, fbx_bcdata, meshes, scene):
 
 def blen_read_material(fbx_tmpl, fbx_obj, settings):
     from bpy_extras import node_shader_utils
+    from math import sqrt
 
     elem_name_utf8 = elem_name_ensure_class(fbx_obj, b'Material')
 
@@ -1333,8 +1334,10 @@ def blen_read_material(fbx_tmpl, fbx_obj, settings):
     # No specular color in Principled BSDF shader, assumed to be either white or take some tint from diffuse one...
     # TODO: add way to handle tint option (guesstimate from spec color + intensity...)?
     ma_wrap.specular = elem_props_get_number(fbx_props, b'SpecularFactor', 0.25) * 2.0
-    # XXX Totally empirical conversion reusing previous 'hardness' computing...
-    ma_wrap.roughness = 1.0 - (((elem_props_get_number(fbx_props, b'Shininess', 9.6) + 3.0) / 5.0) - 0.65)
+    # XXX Totally empirical conversion, trying to adapt it
+    #     (from 1.0 - 0.0 Principled BSDF range to 0.0 - 100.0 FBX shininess range)...
+    fbx_shininess = elem_props_get_number(fbx_props, b'Shininess', 20.0)
+    ma_wrap.roughness = 1.0 - (sqrt(fbx_shininess) / 10.0)
     ma_wrap.transmission = 1.0 - elem_props_get_number(fbx_props, b'Opacity', 1.0)
     ma_wrap.metallic = elem_props_get_number(fbx_props, b'ReflectionFactor', 0.0)
     # We have no metallic (a.k.a. reflection) color...
@@ -2896,17 +2899,17 @@ def load(operator, context, filepath="",
             # So we have to be careful not to re-add endlessly the same material to a mesh!
             # This can easily happen with 'baked' dupliobjects, see T44386.
             # TODO: add an option to link materials to objects in Blender instead?
-            done_mats = set()
+            done_materials = set()
 
             for (fbx_lnk, fbx_lnk_item, fbx_lnk_type) in connection_filter_forward(fbx_uuid, b'Model'):
                 # link materials
                 fbx_lnk_uuid = elem_uuid(fbx_lnk)
                 for (fbx_lnk_material, material, fbx_lnk_material_type) in connection_filter_reverse(fbx_lnk_uuid, b'Material'):
-                    if material not in done_mats:
+                    if material not in done_materials:
                         mesh.materials.append(material)
-                        done_mats.add(material)
+                        done_materials.add(material)
 
-            # We have to validate mesh polygons' mat_idx, see T41015!
+            # We have to validate mesh polygons' ma_idx, see T41015!
             # Some FBX seem to have an extra 'default' material which is not defined in FBX file.
             if mesh.validate_material_indices():
                 print("WARNING: mesh '%s' had invalid material indices, those were reset to first material" % mesh.name)
@@ -2969,15 +2972,15 @@ def load(operator, context, filepath="",
                     if lnk_type in {b'DiffuseColor', b'3dsMax|maps|texmap_diffuse'}:
                         ma_wrap.base_color_texture.image = image
                         texture_mapping_set(fbx_lnk, ma_wrap.base_color_texture)
-                    elif lnk_type == b'SpecularColor':
+                    elif lnk_type in {b'SpecularColor', b'SpecularFactor'}:
                         # Intensity actually, not color...
                         ma_wrap.specular_texture.image = image
                         texture_mapping_set(fbx_lnk, ma_wrap.specular_texture)
-                    elif lnk_type in {b'ReflectionColor', b'3dsMax|maps|texmap_reflection'}:
+                    elif lnk_type in {b'ReflectionColor', b'ReflectionFactor', b'3dsMax|maps|texmap_reflection'}:
                         # Intensity actually, not color...
                         ma_wrap.metallic_texture.image = image
                         texture_mapping_set(fbx_lnk, ma_wrap.metallic_texture)
-                    elif lnk_type == b'TransparentColor':
+                    elif lnk_type in {b'TransparentColor', b'TransparentFactor'}:
                         # Transparency... sort of...
                         ma_wrap.transmission_texture.image = image
                         texture_mapping_set(fbx_lnk, ma_wrap.transmission_texture)