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# SPDX-License-Identifier: Apache-2.0
# Copyright 2018-2021 The glTF-Blender-IO authors.
from io_scene_gltf2.blender.exp import gltf2_blender_gather_texture_info
from io_scene_gltf2.blender.exp import gltf2_blender_get
def detect_shadeless_material(blender_material, export_settings):
"""Detect if this material is "shadeless" ie. should be exported
with KHR_materials_unlit. Returns None if not. Otherwise, returns
a dict with info from parsing the node tree.
"""
if not blender_material.use_nodes: return None
# Old Background node detection (unlikely to happen)
bg_socket = gltf2_blender_get.get_socket(blender_material, "Background")
if bg_socket is not None:
return {'rgb_socket': bg_socket}
# Look for
# * any color socket, connected to...
# * optionally, the lightpath trick, connected to...
# * optionally, a mix-with-transparent (for alpha), connected to...
# * the output node
info = {}
for node in blender_material.node_tree.nodes:
if node.type == 'OUTPUT_MATERIAL' and node.is_active_output:
socket = node.inputs[0]
break
else:
return None
# Be careful not to misidentify a lightpath trick as mix-alpha.
result = __detect_lightpath_trick(socket)
if result is not None:
socket = result['next_socket']
else:
result = __detect_mix_alpha(socket)
if result is not None:
socket = result['next_socket']
info['alpha_socket'] = result['alpha_socket']
result = __detect_lightpath_trick(socket)
if result is not None:
socket = result['next_socket']
# Check if a color socket, or connected to a color socket
if socket.type != 'RGBA':
from_socket = gltf2_blender_get.previous_socket(socket)
if from_socket is None: return None
if from_socket.type != 'RGBA': return None
info['rgb_socket'] = socket
return info
def __detect_mix_alpha(socket):
# Detects this (used for an alpha hookup)
#
# [ Mix ]
# alpha_socket => [Factor ] => socket
# [Transparent] => [Shader ]
# next_socket => [Shader ]
#
# Returns None if not detected. Otherwise, a dict containing alpha_socket
# and next_socket.
prev = gltf2_blender_get.previous_node(socket)
if prev is None or prev.type != 'MIX_SHADER': return None
in1 = gltf2_blender_get.previous_node(prev.inputs[1])
if in1 is None or in1.type != 'BSDF_TRANSPARENT': return None
return {
'alpha_socket': prev.inputs[0],
'next_socket': prev.inputs[2],
}
def __detect_lightpath_trick(socket):
# Detects this (used to prevent casting light on other objects) See ex.
# https://blender.stackexchange.com/a/21535/88681
#
# [ Lightpath ] [ Mix ]
# [ Is Camera Ray] => [Factor ] => socket
# (don't care) => [Shader ]
# next_socket => [ Emission ] => [Shader ]
#
# The Emission node can be omitted.
# Returns None if not detected. Otherwise, a dict containing
# next_socket.
prev = gltf2_blender_get.previous_node(socket)
if prev is None or prev.type != 'MIX_SHADER': return None
in0 = gltf2_blender_get.previous_socket(prev.inputs[0])
if in0 is None or in0.node.type != 'LIGHT_PATH': return None
if in0.name != 'Is Camera Ray': return None
next_socket = prev.inputs[2]
# Detect emission
prev = gltf2_blender_get.previous_node(next_socket)
if prev is not None and prev.type == 'EMISSION':
next_socket = prev.inputs[0]
return {'next_socket': next_socket}
def gather_base_color_factor(info, export_settings):
rgb, alpha = None, None
if 'rgb_socket' in info:
rgb = gltf2_blender_get.get_factor_from_socket(info['rgb_socket'], kind='RGB')
if 'alpha_socket' in info:
alpha = gltf2_blender_get.get_factor_from_socket(info['alpha_socket'], kind='VALUE')
if rgb is None: rgb = [1.0, 1.0, 1.0]
if alpha is None: alpha = 1.0
rgba = [*rgb, alpha]
if rgba == [1, 1, 1, 1]: return None
return rgba
def gather_base_color_texture(info, export_settings):
sockets = (info.get('rgb_socket'), info.get('alpha_socket'))
sockets = tuple(s for s in sockets if s is not None)
if sockets:
# NOTE: separate RGB and Alpha textures will not get combined
# because gather_image determines how to pack images based on the
# names of sockets, and the names are hard-coded to a Principled
# style graph.
unlit_texture, unlit_use_active_uvmap = gltf2_blender_gather_texture_info.gather_texture_info(
sockets[0],
sockets,
export_settings,
)
return unlit_texture, ["unlitTexture"] if unlit_use_active_uvmap else None
return None, None
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