Shaders: update OBJ and FBX for for Principled BSDF emission strength

io_scene_fbx/export_fbx_bin.py

@@ -1309,7 +1309,7 @@ def fbx_data_material_elements(root, ma, scene_data):
     elem_props_template_set(tmpl, props, "p_number", b"DiffuseFactor", 1.0)
     # Principled BSDF only has an emissive color, so we assume factor to be always 1.0.
     elem_props_template_set(tmpl, props, "p_color", b"EmissiveColor", ma_wrap.emission_color)
-    elem_props_template_set(tmpl, props, "p_number", b"EmissiveFactor", 1.0)
+    elem_props_template_set(tmpl, props, "p_number", b"EmissiveFactor", ma_wrap.emission_strength)
     # Not in Principled BSDF, so assuming always 0
     elem_props_template_set(tmpl, props, "p_color", b"AmbientColor", ambient_color)
     elem_props_template_set(tmpl, props, "p_number", b"AmbientFactor", 0.0)
@@ -1808,7 +1808,7 @@ PRINCIPLED_TEXTURE_SOCKETS_TO_FBX = (
     ("base_color_texture", b"DiffuseColor"),
     ("alpha_texture", b"TransparencyFactor"),  # Will be inverted in fact, not much we can do really...
     # ("base_color_texture", b"TransparentColor"),  # Uses diffuse color in Blender!
-    # ("emit", "emit", b"EmissiveFactor"),
+    ("emission_strength_texture", b"EmissiveFactor"),
     ("emission_color_texture", b"EmissiveColor"),
     # ("ambient", "ambient", b"AmbientFactor"),
     # ("", "", b"AmbientColor"),  # World stuff in Blender, for now ignore...

io_scene_fbx/import_fbx.py

@@ -1457,10 +1457,9 @@ def blen_read_material(fbx_tmpl, fbx_obj, settings):
     # We have no metallic (a.k.a. reflection) color...
     # elem_props_get_color_rgb(fbx_props, b'ReflectionColor', const_color_white)
     ma_wrap.normalmap_strength = elem_props_get_number(fbx_props, b'BumpFactor', 1.0)
-    # For emission color we can take into account the factor, but only for default values, not in case of texture.
-    emission_factor = elem_props_get_number(fbx_props, b'EmissiveFactor', 1.0)
-    ma_wrap.emission_color = [c * emission_factor
-                              for c in elem_props_get_color_rgb(fbx_props, b'EmissiveColor', const_color_black)]
+    # Emission strength and color
+    ma_wrap.emission_strength = elem_props_get_number(fbx_props, b'EmissiveFactor', 1.0)
+    ma_wrap.emission_color = elem_props_get_color_rgb(fbx_props, b'EmissiveColor', const_color_black)
 
     nodal_material_wrap_map[ma] = ma_wrap
 
@@ -3151,6 +3150,9 @@ def load(operator, context, filepath="",
                     elif lnk_type in {b'EmissiveColor'}:
                         ma_wrap.emission_color_texture.image = image
                         texture_mapping_set(fbx_lnk, ma_wrap.emission_color_texture)
+                    elif lnk_type in {b'EmissiveFactor'}:
+                        ma_wrap.emission_strength_texture.image = image
+                        texture_mapping_set(fbx_lnk, ma_wrap.emission_strength_texture)
                     else:
                         print("WARNING: material link %r ignored" % lnk_type)
 

io_scene_obj/export_obj.py

@@ -88,7 +88,9 @@ def write_mtl(scene, filepath, path_mode, copy_set, mtl_dict):
                 # XXX TODO Find a way to handle tint and diffuse color, in a consistent way with import...
                 fw('Ks %.6f %.6f %.6f\n' % (mat_wrap.specular, mat_wrap.specular, mat_wrap.specular))  # Specular
                 # Emission, not in original MTL standard but seems pretty common, see T45766.
-                fw('Ke %.6f %.6f %.6f\n' % mat_wrap.emission_color[:3])
+                emission_strength = mat_wrap.emission_strength
+                emission = [emission_strength * c for c in mat_wrap.emission_color[:3]]
+                fw('Ke %.6f %.6f %.6f\n' % tuple(emission))
                 fw('Ni %.6f\n' % mat_wrap.ior)  # Refraction index
                 fw('d %.6f\n' % mat_wrap.alpha)  # Alpha (obj uses 'd' for dissolve)
 
@@ -117,7 +119,7 @@ def write_mtl(scene, filepath, path_mode, copy_set, mtl_dict):
                         "map_Bump": "normalmap_texture",
                         "disp": None,  # displacement...
                         "refl": "metallic_texture",
-                        "map_Ke": "emission_color_texture",
+                        "map_Ke": "emission_color_texture" if emission_strength != 0.0 else None,
                         }
 
                 for key, mat_wrap_key in sorted(image_map.items()):

io_scene_obj/import_obj.py

@@ -195,6 +195,7 @@ def create_materials(filepath, relpath,
 
         elif type == 'Ke':
             _generic_tex_set(mat_wrap.emission_color_texture, image, 'UV', map_offset, map_scale)
+            mat_wrap.emission_strength = 1.0
 
         elif type == 'Bump':
             bump_mult = map_options.get(b'-bm')
@@ -357,6 +358,7 @@ def create_materials(filepath, relpath,
                         # We cannot set context_material.emit right now, we need final diffuse color as well for this.
                         # XXX Unsupported currently
                         context_mat_wrap.emission_color = _get_colors(line_split)
+                        context_mat_wrap.emission_strength = 1.0
                     elif line_id == b'ns':
                         # XXX Totally empirical conversion, trying to adapt it
                         #     (from 0.0 - 900.0 OBJ specular exponent range to 1.0 - 0.0 Principled BSDF range)...