seg.py

import csv
import os
import bpy
import math


def newMaterial(id):
    mat = bpy.data.materials.get(id)

    if mat is None:
        mat = bpy.data.materials.new(name=id)

    mat.use_nodes = True

    if mat.node_tree:
        mat.node_tree.links.clear()
        mat.node_tree.nodes.clear()

    return mat


def newShader(id, type, r, g, b):
    mat = newMaterial(id)

    nodes = mat.node_tree.nodes
    links = mat.node_tree.links
    output = nodes.new(type='ShaderNodeOutputMaterial')

    if type == "diffuse":
        shader = nodes.new(type='ShaderNodeBsdfDiffuse')
        nodes["Diffuse BSDF"].inputs[0].default_value = (r, g, b, 1)

    elif type == "emission":
        shader = nodes.new(type='ShaderNodeEmission')
        nodes["Emission"].inputs[0].default_value = (r, g, b, 1)
        nodes["Emission"].inputs[1].default_value = 1

    elif type == "glossy":
        shader = nodes.new(type='ShaderNodeBsdfGlossy')
        nodes["Glossy BSDF"].inputs[0].default_value = (r, g, b, 1)
        nodes["Glossy BSDF"].inputs[1].default_value = 0

    links.new(shader.outputs[0], output.inputs[0])

    return mat


def to_blender_color(c):
    c = min(max(0, c), 255) / 255
    return c / 12.92 if c < 0.04045 else math.pow((c + 0.055) / 1.055, 2.4)


filename = os.path.abspath(bpy.path.abspath("//color_coding_semantic_segmentation_classes.csv"))
with open(filename) as csv_file:
    csv_reader = csv.reader(csv_file, delimiter=',')
    line_count = 0
    for row in csv_reader:
        if line_count == 0:
            print(f'Column names are {", ".join(row)}')
            line_count += 1
        else:
            print(f'\t Creating shader {row[8]}: {row[5]}')
            r,g,b = row[5].strip("()").split(",")
            newShader(row[8], "emission", to_blender_color(float(r)), to_blender_color(float(g)), to_blender_color(float(b)))
            line_count += 1
    print(f'Processed {line_count} lines.')