blender_script.py

"""Blender script to render images of 3D models.

This script is used to render images of 3D models. It takes in a list of paths
to .glb files and renders images of each model. The images are from rotating the
object around the origin. The images are saved to the output directory.

Example usage:
    blender -b -P blender_script.py -- \
        --object_path my_object.glb \
        --output_dir ./views \
        --engine CYCLES \
        --scale 0.8 \
        --num_images 12 \
        --camera_dist 1.2

Here, input_model_paths.json is a json file containing a list of paths to .glb.
"""

import argparse
import math
import os
import random
import sys
import time
import urllib.request
from typing import Any, Callable, Dict, Generator, List, Literal, Optional, Set, Tuple
# import objaverse
import json

import bpy
import numpy as np
from mathutils import Matrix, Vector


def sample_point_on_sphere(radius: float) -> Tuple[float, float, float]:
    theta = random.random() * 2 * math.pi
    phi = math.acos(2 * random.random() - 1)
    return (
        radius * math.sin(phi) * math.cos(theta),
        radius * math.sin(phi) * math.sin(theta),
        radius * math.cos(phi),
    )


def add_lighting() -> None:
    # # delete the default light
    # bpy.data.objects["Light"].select_set(True)
    # bpy.ops.object.delete()
    # # add a new light
    # bpy.ops.object.light_add(type="AREA")
    # light2 = bpy.data.lights["Area"]
    # light2.energy = 30000
    # bpy.data.objects["Area"].location[2] = 0.5
    # bpy.data.objects["Area"].scale[0] = 100
    # bpy.data.objects["Area"].scale[1] = 100
    # bpy.data.objects["Area"].scale[2] = 100
    # Clear existing lights
    bpy.ops.object.select_all(action="DESELECT")
    bpy.ops.object.select_by_type(type="LIGHT")
    bpy.ops.object.delete()

    # Create key light
    key_light = _create_light(
        name="Key_Light",
        light_type="SUN",
        location=(0, 0, 0),
        rotation=(0.785398, 0, -0.785398),
        energy=random.choice([3, 4, 5]),
    )

    # Create fill light
    fill_light = _create_light(
        name="Fill_Light",
        light_type="SUN",
        location=(0, 0, 0),
        rotation=(0.785398, 0, 2.35619),
        energy=random.choice([2, 3, 4]),
    )

    # Create rim light
    rim_light = _create_light(
        name="Rim_Light",
        light_type="SUN",
        location=(0, 0, 0),
        rotation=(-0.785398, 0, -3.92699),
        energy=random.choice([3, 4, 5]),
    )

    # Create bottom light
    bottom_light = _create_light(
        name="Bottom_Light",
        light_type="SUN",
        location=(0, 0, 0),
        rotation=(3.14159, 0, 0),
        energy=random.choice([1, 2, 3]),
    )

    return dict(
        key_light=key_light,
        fill_light=fill_light,
        rim_light=rim_light,
        bottom_light=bottom_light,
    )


def reset_scene() -> None:
    """Resets the scene to a clean state."""
    # delete everything that isn't part of a camera or a light
    for obj in bpy.data.objects:
        if obj.type not in {"CAMERA", "LIGHT"}:
            bpy.data.objects.remove(obj, do_unlink=True)
    # delete all the materials
    for material in bpy.data.materials:
        bpy.data.materials.remove(material, do_unlink=True)
    # delete all the textures
    for texture in bpy.data.textures:
        bpy.data.textures.remove(texture, do_unlink=True)
    # delete all the images
    for image in bpy.data.images:
        bpy.data.images.remove(image, do_unlink=True)


# load the glb model
def load_object(object_path: str) -> None:
    """Loads a glb model into the scene."""
    if object_path.endswith(".glb"):
        bpy.ops.import_scene.gltf(filepath=object_path, merge_vertices=True)
    elif object_path.endswith(".fbx"):
        bpy.ops.import_scene.fbx(filepath=object_path)
    else:
        raise ValueError(f"Unsupported file type: {object_path}")


def scene_bbox(single_obj=None, ignore_matrix=False):
    bbox_min = (math.inf,) * 3
    bbox_max = (-math.inf,) * 3
    found = False
    for obj in scene_meshes() if single_obj is None else [single_obj]:
        found = True
        for coord in obj.bound_box:
            coord = Vector(coord)
            if not ignore_matrix:
                coord = obj.matrix_world @ coord
            bbox_min = tuple(min(x, y) for x, y in zip(bbox_min, coord))
            bbox_max = tuple(max(x, y) for x, y in zip(bbox_max, coord))
    if not found:
        raise RuntimeError("no objects in scene to compute bounding box for")
    return Vector(bbox_min), Vector(bbox_max)


def scene_root_objects():
    for obj in bpy.context.scene.objects.values():
        if not obj.parent:
            yield obj


def scene_meshes():
    for obj in bpy.context.scene.objects.values():
        if isinstance(obj.data, (bpy.types.Mesh)):
            yield obj


def normalize_scene():
    bbox_min, bbox_max = scene_bbox()
    scale = 1 / max(bbox_max - bbox_min)
    for obj in scene_root_objects():
        obj.scale = obj.scale * scale
    # Apply scale to matrix_world.
    bpy.context.view_layer.update()
    bbox_min, bbox_max = scene_bbox()
    offset = -(bbox_min + bbox_max) / 2
    for obj in scene_root_objects():
        obj.matrix_world.translation += offset
    bpy.ops.object.select_all(action="DESELECT")

    # unparent the camera
    bpy.data.objects["Camera"].parent = None


def setup_camera():
    cam = scene.objects["Camera"]
    cam.location = (0, 1.2, 0)
    cam.data.lens = 35
    cam.data.sensor_width = 32
    cam_constraint = cam.constraints.new(type="TRACK_TO")
    cam_constraint.track_axis = "TRACK_NEGATIVE_Z"
    cam_constraint.up_axis = "UP_Y"
    return cam, cam_constraint


def save_images(object_file: str) -> None:
    """Saves rendered images of the object in the scene."""
    os.makedirs(args.output_dir, exist_ok=True)
    reset_scene()
    # load the object
    load_object(object_file)

    # Set up cameras
    cam = scene.objects["Camera"]
    cam.data.lens = 35
    cam.data.sensor_width = 32

    # Set up camera constraints
    cam_constraint = cam.constraints.new(type="TRACK_TO")
    cam_constraint.track_axis = "TRACK_NEGATIVE_Z"
    cam_constraint.up_axis = "UP_Y"
    empty = bpy.data.objects.new("Empty", None)
    scene.collection.objects.link(empty)
    cam_constraint.target = empty

    uid = os.path.basename(object_file).split(".")[0]
    object_uid = [uid]

    # 保存metadata
    metadata = objaverse.load_annotations(object_uid)

    # save metadata
    metadata_path = os.path.join(args.output_dir, "metadata.json")
    os.makedirs(os.path.dirname(metadata_path), exist_ok=True)
    with open(metadata_path, "w", encoding="utf-8") as f:
        json.dump(metadata, f, sort_keys=True, indent=2)

    normalize_scene()
    add_lighting()
    # cam, cam_constraint = setup_camera()
    # create an empty object to track
    # empty = bpy.data.objects.new("Empty", None)
    # scene.collection.objects.link(empty)
    # cam_constraint.target = empty
    for i in range(args.num_images):
        # set the camera position
        theta = (i / args.num_images) * math.pi * 2
        phi = math.radians(60)
        point = (
            args.camera_dist * math.sin(phi) * math.cos(theta),
            args.camera_dist * math.sin(phi) * math.sin(theta),
            args.camera_dist * math.cos(phi),
        )
        cam.location = point
        # render the image
        render_path = os.path.join(args.output_dir, object_uid, f"{i:03d}.png")
        scene.render.filepath = render_path
        bpy.ops.render.render(write_still=True)


def download_object(object_url: str) -> str:
    """Download the object and return the path."""
    # uid = uuid.uuid4()
    uid = object_url.split("/")[-1].split(".")[0]
    tmp_local_path = os.path.join("tmp-objects", f"{uid}.glb" + ".tmp")
    local_path = os.path.join("tmp-objects", f"{uid}.glb")
    # wget the file and put it in local_path
    os.makedirs(os.path.dirname(tmp_local_path), exist_ok=True)
    urllib.request.urlretrieve(object_url, tmp_local_path)
    os.rename(tmp_local_path, local_path)
    # get the absolute path
    local_path = os.path.abspath(local_path)
    return local_path


if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "--object_path",
        type=str,
        required=True,
        help="Path to the object file",
    )
    parser.add_argument("--output_dir", type=str, default="./views")
    parser.add_argument(
        "--engine", type=str, default="BLENDER_EEVEE", choices=["CYCLES", "BLENDER_EEVEE"]
    )
    parser.add_argument("--num_images", type=int, default=4)
    # 相机距离
    parser.add_argument("--camera_dist", type=int, default=1.5)

    argv = sys.argv[sys.argv.index("--") + 1:]
    args = parser.parse_args(argv)

    context = bpy.context
    scene = context.scene
    render = scene.render

    render.engine = args.engine
    render.image_settings.file_format = "PNG"
    render.image_settings.color_mode = "RGBA"
    render.resolution_x = 512
    render.resolution_y = 512
    render.resolution_percentage = 100

    scene.cycles.device = "GPU"
    scene.cycles.samples = 128
    scene.cycles.diffuse_bounces = 1
    scene.cycles.glossy_bounces = 1
    scene.cycles.transparent_max_bounces = 3
    scene.cycles.transmission_bounces = 3
    scene.cycles.filter_width = 0.01
    scene.cycles.use_denoising = True
    scene.render.film_transparent = True

    bpy.context.preferences.addons["cycles"].preferences.get_devices()
    bpy.context.preferences.addons[
        "cycles"
    ].preferences.compute_device_type = "CUDA"  # or "OPENCL"

    try:
        start_i = time.time()
        if args.object_path.startswith("http"):
            local_path = download_object(args.object_path)
        else:
            local_path = args.object_path
        save_images(local_path)
        end_i = time.time()
        print("Finished", local_path, "in", end_i - start_i, "seconds")
        # delete the object if it was downloaded
        if args.object_path.startswith("http"):
            os.remove(local_path)
    except Exception as e:
        print("Failed to render", args.object_path)
        print(e)