Blender script that imports an OBJ (3D model) exported from Alone in the Dark room viewer application (https://github.com/tigrouind/AITD-roomviewer), and fixes the materials so it can be properly rendered/edited.

convert_aitd_obj.py

# Blender script that imports an OBJ (3D model) exported from Alone in the Dark
# room viewer application (https://github.com/tigrouind/AITD-roomviewer), and
# fixes the materials so it can be properly rendered/edited.

# NOTE: the file "noise.png" is needed (get it from the Assets/Materials/Model/
# directory of the mentioned application). Put it in the same folder as this
# script so Blender can find it. It will also have to be present in the same
# folder as the output .blend file, unless you manually change the path or pack
# (embed) it into the .blend.

# Usage:
#     blender --background --python <script.py> -- -f <file.obj> [-o <file.blend>]

import bpy
import sys
import os
import argparse

USAGE_TEXT = "Usage:\n\tblender --background --python " + __file__ + " -- -f <file.obj> [-o <file.blend>]"
SUPPORTED_MATERIALS = {"shadeless", "noise", "glass", "metal_horizontal", "metal_vertical"}


def main():
	argv = sys.argv

	# "--" (with spaces before and after) separates the Blender arguments from
	# the Python script ones. We recover these arguments (if there are any).
	if "--" not in argv:
		print(USAGE_TEXT)
		return
	else:
		argv = argv[argv.index("--") + 1:]

	# Use the handy ArgumentParser to do the job for us.
	argParser = argparse.ArgumentParser(description=USAGE_TEXT)

	argParser.add_argument("-f", "--file", dest="inFile", type=str, required=True, help="The .obj file that will be read.")
	argParser.add_argument("-o", "--output", dest="outFile", type=str, required=False, help="The .blend file that will be saved (optional).", default="untitled.blend")

	args = argParser.parse_args(argv)

	if not args.inFile:
		print(USAGE_TEXT)
		return

	# Part 1: clear the scene (remove all objects).
	bpy.ops.wm.read_factory_settings(use_empty=True)

	# Part 2: try to import the .obj file into Blender.
	# Optional interesting arguments for obj_import():
	#     global_scale (default 1.0)
	#     clamp_size   (default 0.0)
	#     forward_axis (default "NEGATIVE_Z")
	#     up_axis      (default "Y")
	# Check reference at https://docs.blender.org/api/current/bpy.ops.wm.html#bpy.ops.wm.obj_import
	result = str(bpy.ops.wm.obj_import(filepath=args.inFile, forward_axis="Z"))
	result = result.strip() # Remove leading and trailing spaces.
	if result != "{'FINISHED'}":
		print("There was an error trying to import the chosen OBJ. Check that it is a valid file.")
		return

	# Part 3: fix the materials.
	# Check reference at https://github.com/tigrouind/AITD-roomviewer/blob/master/README.md#obj-export
	for material in bpy.data.materials:
		# We will only fix these materials we're interested in. We will avoid
		# messing with others (in case there's any).
		if material.name not in SUPPORTED_MATERIALS:
			continue
		material.use_nodes = True
		material.node_tree.nodes.clear()
		# SHADELESS (standard, plain color with no effects).
		if material.name == "shadeless":
			nodeVertexColor = material.node_tree.nodes.new("ShaderNodeVertexColor")
			nodeVertexColor.location = (0, 0)
			nodeOutput = material.node_tree.nodes.new("ShaderNodeOutputMaterial")
			nodeOutput.location = (200, 0)
			material.node_tree.links.new(nodeOutput.inputs["Surface"], nodeVertexColor.outputs["Color"])
		# NOISE (noisy pattern mixed with the plain color).
		elif material.name == "noise":
			nodeVertexColor = material.node_tree.nodes.new("ShaderNodeVertexColor")
			nodeVertexColor.location = (100, 150)
			nodeImageTexture = material.node_tree.nodes.new("ShaderNodeTexImage")
			bpy.ops.image.open(directory=os.getcwd(), files=[{"name": "noise.png"}], relative_path=True)
			noiseImage = bpy.data.images["noise.png"]
			nodeImageTexture.image = noiseImage
			nodeImageTexture.location = (0, 0)
			nodeMix = material.node_tree.nodes.new("ShaderNodeMix")
			nodeMix.data_type = "RGBA"
			nodeMix.blend_type = "MULTIPLY"
			nodeMix.clamp_factor = True
			nodeMix.inputs["Factor"].default_value = 0.5
			nodeMix.location = (350, 150)
			nodeOutput = material.node_tree.nodes.new("ShaderNodeOutputMaterial")
			nodeOutput.location = (550, 150)
			material.node_tree.links.new(nodeMix.inputs["A"], nodeVertexColor.outputs["Color"])
			material.node_tree.links.new(nodeMix.inputs["B"], nodeImageTexture.outputs["Color"])
			material.node_tree.links.new(nodeOutput.inputs["Surface"], nodeMix.outputs["Result"])
		# GLASS (surfaces with simple transparency and no refraction, where
		#     white -> fully transparent
		#     black -> fully opaque
		# and all other colors having an intermediate degree of transparency).
		elif material.name == "glass":
			nodeVertexColor = material.node_tree.nodes.new("ShaderNodeVertexColor")
			nodeVertexColor.location = (0, 0)
			nodeShader = material.node_tree.nodes.new("ShaderNodeBsdfTransparent")
			nodeShader.location = (200, 0)
			nodeOutput = material.node_tree.nodes.new("ShaderNodeOutputMaterial")
			nodeOutput.location = (400, 0)
			material.node_tree.links.new(nodeShader.inputs["Color"], nodeVertexColor.outputs["Color"])
			material.node_tree.links.new(nodeOutput.inputs["Surface"], nodeShader.outputs["BSDF"])
			material.blend_method = "BLEND"
		# METAL_HORIZONTAL / METAL_VERTICAL (metallic surfaces, with a gradient).
		elif material.name == "metal_horizontal" or material.name == "metal_vertical":
			nodeTexCoord = material.node_tree.nodes.new("ShaderNodeTexCoord")
			nodeTexCoord.location = (0, 0)
			nodeSeparateXYZ = material.node_tree.nodes.new("ShaderNodeSeparateXYZ")
			nodeSeparateXYZ.location = (200, 0)
			nodeMultiply = material.node_tree.nodes.new("ShaderNodeMath")
			nodeMultiply.operation = "MULTIPLY"
			nodeMultiply.inputs[1].default_value = 5.0
			nodeMultiply.location = (400, 0)
			nodePingPong = material.node_tree.nodes.new("ShaderNodeMath")
			nodePingPong.operation = "PINGPONG"
			nodePingPong.inputs[1].default_value = 1.0
			nodePingPong.location = (600, 0)
			nodeAdd = material.node_tree.nodes.new("ShaderNodeMath")
			nodeAdd.operation = "ADD"
			nodeAdd.inputs[1].default_value = 0.5
			nodeAdd.location = (800, 0)
			nodeVertexColor = material.node_tree.nodes.new("ShaderNodeVertexColor")
			nodeVertexColor.location = (800, 150)
			nodeGamma = material.node_tree.nodes.new("ShaderNodeGamma")
			nodeGamma.location = (1000, 100)
			nodeOutput = material.node_tree.nodes.new("ShaderNodeOutputMaterial")
			nodeOutput.location = (1200, 100)
			material.node_tree.links.new(nodeSeparateXYZ.inputs["Vector"], nodeTexCoord.outputs["Window"])
			if material.name == "metal_horizontal":
				material.node_tree.links.new(nodeMultiply.inputs[0], nodeSeparateXYZ.outputs["X"])
			elif material.name == "metal_vertical":
				material.node_tree.links.new(nodeMultiply.inputs[0], nodeSeparateXYZ.outputs["Y"])
			material.node_tree.links.new(nodePingPong.inputs[0], nodeMultiply.outputs["Value"])
			material.node_tree.links.new(nodeAdd.inputs[0], nodePingPong.outputs["Value"])
			material.node_tree.links.new(nodeGamma.inputs["Color"], nodeVertexColor.outputs["Color"])
			material.node_tree.links.new(nodeGamma.inputs["Gamma"], nodeAdd.outputs["Value"])
			material.node_tree.links.new(nodeOutput.inputs["Surface"], nodeGamma.outputs["Color"])

	# Part 4: set the 3D viewport shading mode to "material preview", to allow
	# a quick check upon opening the .blend file without having to do anything.
	for screenArea in bpy.context.screen.areas:
		if screenArea.type == "VIEW_3D":
			screenArea.spaces[0].shading.type = "MATERIAL"

	# Part 5: save the .blend result file.
	bpy.ops.wm.save_mainfile(filepath=args.outFile)
	# Blender does not allow to set relative paths before saving the file. To
	# prevent errors with "noise.png" not being found, we do it now and resave.
	bpy.ops.file.make_paths_relative()
	bpy.ops.wm.save_mainfile()


if __name__ == "__main__":
	main()

In order to batch convert many files, you can use the following PowerShell script (e.g. save it as convert_aitd_obj.ps1):

Get-ChildItem .\*.obj | Foreach-Object `
	{.\blender.exe --background --python .\convert_aitd_obj.py -- -f $_.Name -o "$($_.BaseName).blend"}