Fix T70666: OBJ IO: Add support for new Emission option of Principled BSDF.

io_scene_obj/__init__.py

@@ -21,7 +21,7 @@
 bl_info = {
     "name": "Wavefront OBJ format",
     "author": "Campbell Barton, Bastien Montagne",
-    "version": (3, 6, 0),
+    "version": (3, 7, 0),
     "blender": (2, 81, 6),
     "location": "File > Import-Export",
     "description": "Import-Export OBJ, Import OBJ mesh, UV's, materials and textures",

io_scene_obj/export_obj.py

@@ -91,8 +91,7 @@ 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.
-                # XXX Not supported by current Principled-based shader.
-                fw('Ke 0.0 0.0 0.0\n')
+                fw('Ke %.6f %.6f %.6f\n' % mat_wrap.emission_color[:3])
                 fw('Ni %.6f\n' % mat_wrap.ior)  # Refraction index
                 fw('d %.6f\n' % mat_wrap.alpha)  # Alpha (obj uses 'd' for dissolve)
 
@@ -121,7 +120,7 @@ def write_mtl(scene, filepath, path_mode, copy_set, mtl_dict):
                         "map_Bump": "normalmap_texture",
                         "disp": None,  # displacement...
                         "refl": "metallic_texture",
-                        "map_Ke": None  # emission...
+                        "map_Ke": "emission_color_texture",
                         }
 
                 for key, mat_wrap_key in sorted(image_map.items()):

io_scene_obj/import_obj.py

@@ -187,8 +187,7 @@ def create_materials(filepath, relpath,
             _generic_tex_set(mat_wrap.specular_texture, image, 'UV', map_offset, map_scale)
 
         elif type == 'Ke':
-            # XXX Not supported?
-            print("WARNING, currently unsupported emit texture, skipped.")
+            _generic_tex_set(mat_wrap.emission_color_texture, image, 'UV', map_offset, map_scale)
 
         elif type == 'Bump':
             bump_mult = map_options.get(b'-bm')
@@ -218,7 +217,7 @@ def create_materials(filepath, relpath,
         else:
             raise Exception("invalid type %r" % type)
 
-    def finalize_material(context_material, context_material_vars, spec_colors, emit_colors,
+    def finalize_material(context_material, context_material_vars, spec_colors,
                           do_highlight, do_reflection, do_transparency, do_glass):
         # Finalize previous mat, if any.
         if context_material:
@@ -237,14 +236,6 @@ def create_materials(filepath, relpath,
                 if "roughness" not in context_material_vars:
                     context_mat_wrap.roughness = 0.0
 
-
-            emit_value = sum(emit_colors) / 3.0
-            if emit_value > 1e-6:
-                print("WARNING, emit value unsupported by Principled BSDF shader, skipped.")
-                # We have to adapt it to diffuse color too...
-                emit_value /= sum(tuple(context_material.diffuse_color)[:3]) / 3.0
-            # ~ context_material.emit = emit_value
-
             # FIXME, how else to use this?
             if do_highlight:
                 if "specular" not in context_material_vars:
@@ -303,7 +294,6 @@ def create_materials(filepath, relpath,
             do_transparency = False
             do_glass = False
             spec_colors = [0.0, 0.0, 0.0]
-            emit_colors = [0.0, 0.0, 0.0]
 
             # print('\t\tloading mtl: %e' % mtlpath)
             context_material = None
@@ -319,7 +309,7 @@ def create_materials(filepath, relpath,
 
                 if line_id == b'newmtl':
                     # Finalize previous mat, if any.
-                    finalize_material(context_material, context_material_vars, spec_colors, emit_colors,
+                    finalize_material(context_material, context_material_vars, spec_colors,
                                       do_highlight, do_reflection, do_transparency, do_glass)
 
                     context_material_name = line_value(line_split)
@@ -328,8 +318,7 @@ def create_materials(filepath, relpath,
                         context_mat_wrap = nodal_material_wrap_map[context_material]
                     context_material_vars.clear()
 
-                    spec_colors = [0.0, 0.0, 0.0]
-                    emit_colors[:] = [0.0, 0.0, 0.0]
+                    spec_colors[:] = [0.0, 0.0, 0.0]
                     do_highlight = False
                     do_reflection = False
                     do_transparency = False
@@ -352,8 +341,8 @@ def create_materials(filepath, relpath,
                     elif line_id == b'ke':
                         # We cannot set context_material.emit right now, we need final diffuse color as well for this.
                         # XXX Unsupported currently
-                        emit_colors[:] = [
-                            float_func(line_split[1]), float_func(line_split[2]), float_func(line_split[3])]
+                        col = (float_func(line_split[1]), float_func(line_split[2]), float_func(line_split[3]))
+                        context_mat_wrap.emission_color = col
                     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)...
@@ -469,7 +458,7 @@ def create_materials(filepath, relpath,
                         print("WARNING: %r:%r (ignored)" % (filepath, line))
 
             # Finalize last mat, if any.
-            finalize_material(context_material, context_material_vars, spec_colors, emit_colors,
+            finalize_material(context_material, context_material_vars, spec_colors,
                               do_highlight, do_reflection, do_transparency, do_glass)
             mtl.close()