Script to create a three-light set-up scene in Blender

threelights.blender.py

# threelights.blender.py
# By Rémino Rem <remino.net>
# 2023-11-18
#
# This creates a three-light scene set-up in Blender. Works in Blender 4.
#
# Best run in a blank file, as it will destroy anything in the scene.

import bpy
import mathutils

# Clear existing objects except camera
for obj in bpy.context.scene.objects:
    if obj.type != 'CAMERA':
        obj.select_set(True)
    else:
        obj.select_set(False)
bpy.ops.object.delete()

# Create a cube
bpy.ops.mesh.primitive_cube_add(size=2, enter_editmode=False, align='WORLD', location=(0, 0, 1))
cube = bpy.context.object

# Function to create a light
def create_light(name, type, location, energy, rotation):
    bpy.ops.object.light_add(type=type, radius=1, align='WORLD', location=location)
    light = bpy.context.object
    light.data.energy = energy
    light.name = name
    light.rotation_euler = rotation

# Create Key Light, positioned and angled towards the subject
key_light_location = (5, -5, 5)
key_light_direction = mathutils.Vector(cube.location) - mathutils.Vector(key_light_location)
key_light_rotation = key_light_direction.to_track_quat('-Z', 'X').to_euler()
create_light('Key Light', 'AREA', key_light_location, 1000, key_light_rotation)

# Create Fill Light
create_light('Fill Light', 'AREA', (5, 5, 5), 300, (-0.785398, 0, -0.785398))

# Create Back Light, positioned to the left from the camera's POV and pointing forward and left
create_light('Back Light', 'AREA', (-5, -5, 5), 500, (0.785398, -0.261799, 0))

# Position and rotate the camera to face the cube
camera_location = (10, 0, 5)  # Position between Key and Fill lights
if not any(obj.type == 'CAMERA' for obj in bpy.context.scene.objects):
    bpy.ops.object.camera_add(location=camera_location)
    camera = bpy.context.object
else:
    camera = next(obj for obj in bpy.context.scene.objects if obj.type == 'CAMERA')
    camera.location = camera_location

# Calculate the direction vector from the camera to the cube
direction = mathutils.Vector(cube.location) - mathutils.Vector(camera.location)
# Point the camera's '-Z' and use its 'Y' as up
rot_quat = direction.to_track_quat('-Z', 'Y')
camera.rotation_euler = rot_quat.to_euler()