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KhronosGroup / glTF-Blender-IO

Blender glTF 2.0 importer and exporter
https://docs.blender.org/manual/en/latest/addons/import_export/scene_gltf2.html
Apache License 2.0
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Export crash when specular = 0 and IOR = 1 #1751

Closed nbvdkamp closed 2 years ago

nbvdkamp commented 2 years ago

Describe the bug When exporting a file with a model using a principled BSDF material that has a specular value of 0.0 and an IOR of 1.0 a ZeroDivisionError occurs and the export fails.

The stack trace:

Traceback (most recent call last):
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\__init__.py", line 648, in execute
    return gltf2_blender_export.save(context, export_settings)
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_export.py", line 35, in save
    json, buffer = __export(export_settings)
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_export.py", line 52, in __export
    __gather_gltf(exporter, export_settings)
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_export.py", line 66, in __gather_gltf
    active_scene_idx, scenes, animations = gltf2_blender_gather.gather_gltf2(export_settings)
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather.py", line 30, in gather_gltf2
    scenes.append(__gather_scene(blender_scene, export_settings))
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_cache.py", line 38, in wrapper_cached
    result = func(*args, **kwargs)
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather.py", line 69, in __gather_scene
    node = gltf2_blender_gather_nodes.gather_node(
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_nodes.py", line 35, in gather_node
    mesh=__gather_mesh(vnode, blender_object, export_settings),
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_nodes.py", line 246, in __gather_mesh
    result = gltf2_blender_gather_mesh.gather_mesh(blender_mesh,
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_cache.py", line 38, in wrapper_cached
    result = func(*args, **kwargs)
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_mesh.py", line 61, in gather_mesh
    primitives=__gather_primitives(blender_mesh, uuid_for_skined_data, vertex_groups, modifiers, materials, export_settings),
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_mesh.py", line 147, in __gather_primitives
    return gltf2_blender_gather_primitives.gather_primitives(blender_mesh,
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_cache.py", line 38, in wrapper_cached
    result = func(*args, **kwargs)
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_primitives.py", line 83, in gather_primitives
    material = gltf2_blender_gather_materials.gather_material(
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_cache.py", line 38, in wrapper_cached
    result = func(*args, **kwargs)
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_materials.py", line 57, in gather_material
    extensions, uvmap_actives_extensions = __gather_extensions(blender_material, emissive_factor, export_settings)
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_materials.py", line 250, in __gather_extensions
    specular_extension, use_actives_uvmap_specular = export_specular(blender_material, export_settings)
  File "E:\Program Files\Blender Foundation\blender-3.3.1-windows-x64\3.3\scripts\addons\io_scene_gltf2\blender\exp\gltf2_blender_gather_materials_specular.py", line 124, in export_specular
    specular_color = (1 - transmission) * (1 / f0_from_ior) * 0.08 * specular * tint_strength + transmission * tint_strength
ZeroDivisionError: float division by zero

To Reproduce Create a file with a model using a principled BSDF material that has a specular value of 0.0 and an IOR of 1.0 and try to export the file.

Expected behavior The scene successfully exports

Screenshots If applicable, add screenshots to help explain your problem.

.blend file Very simple to reproduce but here is one anyway: export_crash_bug.zip

Version Blender 3.3.1 on Windows

julienduroure commented 2 years ago

Confirmed. No need to have specular 0.0 ==> IOR = 0.0 and any specular != 0.5