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# SPDX-License-Identifier: Apache-2.0
# Copyright 2018-2022 The glTF-Blender-IO authors.
import bpy
from io_scene_gltf2.io.com.gltf2_io_extensions import Extension
from io_scene_gltf2.blender.exp import gltf2_blender_get
from io_scene_gltf2.blender.exp import gltf2_blender_gather_texture_info
def export_volume(blender_material, export_settings):
# Implementation based on https://github.com/KhronosGroup/glTF-Blender-IO/issues/1454#issuecomment-928319444
# If no transmission --> No volume
transmission_enabled = False
transmission_socket = gltf2_blender_get.get_socket(blender_material, 'Transmission')
if isinstance(transmission_socket, bpy.types.NodeSocket) and not transmission_socket.is_linked:
transmission_enabled = transmission_socket.default_value > 0
elif gltf2_blender_get.has_image_node_from_socket(transmission_socket):
transmission_enabled = True
if transmission_enabled is False:
return None, None
volume_extension = {}
has_thickness_texture = False
thickness_slots = ()
thicknesss_socket = gltf2_blender_get.get_socket_old(blender_material, 'Thickness')
if thicknesss_socket is None:
# If no thickness (here because there is no glTF Material Output node), no volume extension export
return None, None
density_socket = gltf2_blender_get.get_socket(blender_material, 'Density', volume=True)
attenuation_color_socket = gltf2_blender_get.get_socket(blender_material, 'Color', volume=True)
# Even if density or attenuation are not set, we export volume extension
if isinstance(attenuation_color_socket, bpy.types.NodeSocket):
rgb = gltf2_blender_get.get_const_from_default_value_socket(attenuation_color_socket, kind='RGB')
volume_extension['attenuationColor'] = rgb
if isinstance(density_socket, bpy.types.NodeSocket):
density = gltf2_blender_get.get_const_from_default_value_socket(density_socket, kind='VALUE')
volume_extension['attenuationDistance'] = 1.0 / density if density != 0 else None # infinity (Using None as glTF default)
if isinstance(thicknesss_socket, bpy.types.NodeSocket) and not thicknesss_socket.is_linked:
val = thicknesss_socket.default_value
if val == 0.0:
# If no thickness, no volume extension export
return None, None
volume_extension['thicknessFactor'] = val
elif gltf2_blender_get.has_image_node_from_socket(thicknesss_socket):
fac = gltf2_blender_get.get_factor_from_socket(thicknesss_socket, kind='VALUE')
# default value in glTF is 0.0, but if there is a texture without factor, use 1
volume_extension['thicknessFactor'] = fac if fac != None else 1.0
has_thickness_texture = True
# Pack thickness channel (R).
if has_thickness_texture:
thickness_slots = (thicknesss_socket,)
use_actives_uvmaps = []
if len(thickness_slots) > 0:
combined_texture, use_active_uvmap, _ = gltf2_blender_gather_texture_info.gather_texture_info(
thicknesss_socket,
thickness_slots,
export_settings,
)
if has_thickness_texture:
volume_extension['thicknessTexture'] = combined_texture
if use_active_uvmap:
use_actives_uvmaps.append("thicknessTexture")
return Extension('KHR_materials_volume', volume_extension, False), use_actives_uvmaps
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