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import json
import math
import sys
from pathlib import Path
import bpy
import numpy as np
from mathutils import Vector
IMPORTERS = {
"obj": bpy.ops.wm.obj_import,
"ply": bpy.ops.wm.ply_import,
"glb": bpy.ops.import_scene.gltf,
"gltf": bpy.ops.import_scene.gltf,
"fbx": bpy.ops.import_scene.fbx,
"stl": bpy.ops.import_mesh.stl,
}
def orthographic_views(num_views: int) -> list[dict[str, float]]:
base_views = [
(-0.5 * np.pi, 0.0),
(0.0, 0.0),
(0.5 * np.pi, 0.0),
(np.pi, 0.0),
(-0.5 * np.pi, 0.5 * np.pi),
(-0.5 * np.pi, -0.5 * np.pi),
]
if num_views <= len(base_views):
selected = base_views[:num_views]
else:
selected = base_views[:]
for index in range(num_views - len(base_views)):
azimuth = 2.0 * np.pi * index / max(1, num_views - len(base_views))
selected.append((azimuth, np.pi / 6.0))
return [{"azimuth": yaw, "elevation": pitch, "distance": 1.5, "fov": 0.6} for yaw, pitch in selected]
def clear_scene() -> None:
for collection in (bpy.data.objects, bpy.data.materials, bpy.data.textures, bpy.data.images):
for item in list(collection):
collection.remove(item, do_unlink=True)
def load_model(path: Path) -> None:
extension = path.suffix.lower().lstrip(".")
if extension not in IMPORTERS:
raise ValueError(f"Unsupported model format: {path.suffix}")
importer = IMPORTERS[extension]
if extension in {"glb", "gltf"}:
importer(filepath=str(path), merge_vertices=True, import_shading="NORMALS")
else:
importer(filepath=str(path))
def scene_bbox() -> tuple[Vector, Vector]:
bbox_min = Vector((math.inf, math.inf, math.inf))
bbox_max = Vector((-math.inf, -math.inf, -math.inf))
found = False
for obj in bpy.context.scene.objects:
if not isinstance(obj.data, bpy.types.Mesh):
continue
found = True
for coord in obj.bound_box:
world_coord = obj.matrix_world @ Vector(coord)
bbox_min = Vector(tuple(min(bbox_min[i], world_coord[i]) for i in range(3)))
bbox_max = Vector(tuple(max(bbox_max[i], world_coord[i]) for i in range(3)))
if not found:
raise RuntimeError("The scene does not contain a mesh object.")
return bbox_min, bbox_max
def normalize_scene() -> tuple[float, Vector]:
root_objects = [obj for obj in bpy.context.scene.objects if obj.parent is None]
if len(root_objects) > 1:
parent = bpy.data.objects.new("SceneRoot", None)
bpy.context.scene.collection.objects.link(parent)
for obj in root_objects:
obj.parent = parent
else:
parent = root_objects[0]
bbox_min, bbox_max = scene_bbox()
scale = 1.0 / max(bbox_max - bbox_min)
parent.scale *= scale
bpy.context.view_layer.update()
bbox_min, bbox_max = scene_bbox()
offset = -(bbox_min + bbox_max) * 0.5
parent.matrix_world.translation += offset
bpy.context.view_layer.update()
return scale, offset
def configure_render(resolution: int, engine: str) -> None:
scene = bpy.context.scene
scene.render.engine = engine
scene.render.resolution_x = resolution
scene.render.resolution_y = resolution
scene.render.resolution_percentage = 100
scene.render.image_settings.file_format = "PNG"
scene.render.image_settings.color_mode = "RGBA"
scene.render.film_transparent = True
if engine == "CYCLES":
scene.cycles.device = "GPU"
scene.cycles.samples = 64
scene.cycles.use_denoising = True
try:
prefs = bpy.context.preferences.addons["cycles"].preferences
prefs.compute_device_type = "CUDA"
prefs.get_devices()
for device in prefs.devices:
device.use = device.type == "CUDA"
except Exception:
pass
def create_camera() -> bpy.types.Object:
camera = bpy.data.objects.new("Camera", bpy.data.cameras.new("Camera"))
bpy.context.collection.objects.link(camera)
bpy.context.scene.camera = camera
camera.data.type = "ORTHO"
camera.data.ortho_scale = 1.2
target = bpy.data.objects.new("CameraTarget", None)
bpy.context.collection.objects.link(target)
target.location = (0.0, 0.0, 0.0)
constraint = camera.constraints.new(type="TRACK_TO")
constraint.track_axis = "TRACK_NEGATIVE_Z"
constraint.up_axis = "UP_Y"
constraint.target = target
return camera
def add_lighting() -> None:
light_specs = [
("KeyLight", "POINT", 1000.0, (4.0, 1.0, 6.0), (1.0, 1.0, 1.0)),
("TopLight", "AREA", 10000.0, (0.0, 0.0, 10.0), (100.0, 100.0, 100.0)),
("BottomLight", "AREA", 1000.0, (0.0, 0.0, -10.0), (100.0, 100.0, 100.0)),
]
for name, kind, energy, location, scale in light_specs:
light = bpy.data.objects.new(name, bpy.data.lights.new(name, type=kind))
bpy.context.collection.objects.link(light)
light.data.energy = energy
light.location = location
light.scale = scale
def apply_neutral_material() -> None:
material = bpy.data.materials.new("NeutralMaterial")
material.use_nodes = True
material.node_tree.nodes.clear()
shader = material.node_tree.nodes.new("ShaderNodeBsdfDiffuse")
shader.inputs[0].default_value = (0.5, 0.5, 0.5, 1.0)
output = material.node_tree.nodes.new("ShaderNodeOutputMaterial")
material.node_tree.links.new(shader.outputs["BSDF"], output.inputs["Surface"])
bpy.context.scene.view_layers["ViewLayer"].material_override = material
def camera_transform(camera: bpy.types.Object) -> list[list[float]]:
location, rotation, _ = camera.matrix_world.decompose()
rotation = rotation.to_matrix()
rows = []
for row_index in range(3):
row = [rotation[row_index][col_index] for col_index in range(3)]
row.append(location[row_index])
rows.append(row)
rows.append([0.0, 0.0, 0.0, 1.0])
return rows
def export_mesh(path: Path) -> None:
bpy.ops.object.select_all(action="DESELECT")
mesh_objects = [obj for obj in bpy.context.scene.objects if obj.type == "MESH"]
if not mesh_objects:
return
bpy.context.view_layer.objects.active = mesh_objects[0]
for obj in mesh_objects:
obj.select_set(True)
bpy.ops.object.convert(target="MESH")
bpy.ops.object.mode_set(mode="EDIT")
bpy.ops.mesh.select_all(action="SELECT")
bpy.ops.mesh.quads_convert_to_tris(quad_method="BEAUTY", ngon_method="BEAUTY")
bpy.ops.object.mode_set(mode="OBJECT")
bpy.ops.wm.ply_export(filepath=str(path), export_triangulated_mesh=True, up_axis="Y", forward_axis="NEGATIVE_Z")
def render(args: argparse.Namespace) -> None:
output_dir = Path(args.output_folder)
output_dir.mkdir(parents=True, exist_ok=True)
clear_scene()
load_model(Path(args.object))
scale, offset = normalize_scene()
configure_render(args.resolution, args.engine)
camera = create_camera()
add_lighting()
apply_neutral_material()
metadata = {
"aabb": [[-0.5, -0.5, -0.5], [0.5, 0.5, 0.5]],
"scale": scale,
"offset": [offset.x, offset.y, offset.z],
"frames": [],
}
for index, view in enumerate(orthographic_views(args.num_views)):
camera.location = (
view["distance"] * np.cos(view["azimuth"]) * np.cos(view["elevation"]),
view["distance"] * np.sin(view["azimuth"]) * np.cos(view["elevation"]),
view["distance"] * np.sin(view["elevation"]),
)
bpy.context.scene.render.filepath = str(output_dir / f"{index:03d}.png")
bpy.ops.render.render(write_still=True)
metadata["frames"].append(
{
"file_path": f"{index:03d}.png",
"camera_angle_x": view["fov"],
"azimuth": view["azimuth"],
"elevation": view["elevation"],
"cam_dis": view["distance"],
"transform_matrix": camera_transform(camera),
}
)
with (output_dir / "transforms.json").open("w") as handle:
json.dump(metadata, handle, indent=2)
if args.geo_mode:
export_mesh(output_dir / "mesh.ply")
def build_parser() -> argparse.ArgumentParser:
parser = argparse.ArgumentParser(description="Render a 3D model from fixed orthographic views.")
parser.add_argument("--object", required=True, help="Path to the model file.")
parser.add_argument("--output-folder", "--output_folder", dest="output_folder", required=True)
parser.add_argument("--resolution", type=int, default=512)
parser.add_argument("--num-views", type=int, default=6)
parser.add_argument("--engine", default="CYCLES", choices=("CYCLES", "BLENDER_EEVEE_NEXT", "BLENDER_EEVEE"))
parser.add_argument("--geo-mode", "--geo_mode", dest="geo_mode", action="store_true")
return parser
if __name__ == "__main__":
argv = sys.argv[sys.argv.index("--") + 1 :] if "--" in sys.argv else sys.argv[1:]
render(build_parser().parse_args(argv))
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