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OBJ IO: Change specular IO conversion. 

Conversion from phong exponent to Principled BSDF is expected to be
quadratic afaik, not linear.
This commit is contained in:
Bastien Montagne 2018-10-16 16:34:37 +02:00
parent 295cdaa5c7
commit 0f84063c58
3 changed files with 11 additions and 6 deletions
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2
io_scene_obj/__init__.py
View File

@ -21,7 +21,7 @@
bl_info = {
"name": "Wavefront OBJ format",
"author": "Campbell Barton, Bastien Montagne",
"version": (3, 4, 1),
"version": (3, 4, 2),
"blender": (2, 80, 0),
"location": "File > Import-Export",
"description": "Import-Export OBJ, Import OBJ mesh, UV's, materials and textures",

8
io_scene_obj/export_obj.py
View File

@ -73,9 +73,11 @@ def write_mtl(scene, filepath, path_mode, copy_set, mtl_dict):
use_mirror = mat_wrap.metallic != 0.0
use_transparency = mat_wrap.transmission != 0.0
# Convert from principled roughness to 0 - 1000 specular range.
# XXX Basic linear conversion, what would be best-matching formula here?
fw('Ns %.6f\n' % ((1.0 - mat_wrap.roughness) * 1000))
# XXX Totally empirical conversion, trying to adapt it
# (from 1.0 - 0.0 Principled BSDF range to 0.0 - 900.0 OBJ specular exponent range)...
spec = (1.0 - mat_wrap.roughness) * 30
spec *= spec
fw('Ns %.6f\n' % spec)
# Ambient
if use_mirror:

7
io_scene_obj/import_obj.py
View File

@ -93,6 +93,8 @@ def create_materials(filepath, relpath,
Create all the used materials in this obj,
assign colors and images to the materials from all referenced material libs
"""
from math import sqrt
DIR = os.path.dirname(filepath)
context_material_vars = set()
@ -303,8 +305,9 @@ def create_materials(filepath, relpath,
emit_colors[:] = [
float_func(line_split[1]), float_func(line_split[2]), float_func(line_split[3])]
elif line_id == b'ns':
# XXX Basic linear conversion, what would be best-matching formula here?
context_mat_wrap.roughness = 1.0 - (float_func(line_split[1]) / 1000)
# 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)...
context_mat_wrap.roughness = 1.0 - (sqrt(float_func(line_split[1])) / 30)
context_material_vars.add("roughness")
elif line_id == b'ni': # Refraction index (between 0.001 and 10).
context_mat_wrap.ior = float_func(line_split[1])