simple-3d

(en) This is the English README.
(ja) 日本語版はこちらです。

Overview

This package is a Python port of the simple_3d Dart/Flutter package. It is a working Python implementation of Simple 3D Format.

Simple 3D Format is a file format that makes it easy for non-experts to handle 3D objects. Files output in this format have the extension .sp3d, and the internal classes are converted to JSON. All data about one object is contained in one file.

This specification aims to minimize complexity, make it easier to read in a text editor, and make it versatile. Made for science, it can be difficult to use in other genres. For the development of science, the goal is to be able to use it without being affected by interests and conflicts.

The JSON serialization is fully compatible with the Dart version, so .sp3d files can be exchanged between Python and Dart/Flutter environments.

Installation

pip install simple-3d

Usage

Quick Start

from simple_3d import Sp3dObj, Sp3dV3D, Sp3dFragment, Sp3dFace, Sp3dMaterial, Sp3dColor
import math

sp3d_obj = Sp3dObj(
    [Sp3dV3D(0, 0, 0)],
    [
        Sp3dFragment(
            [Sp3dFace([0], 0)],
            is_particle=True,
            r=1.0,
        )
    ],
    [
        Sp3dMaterial(
            Sp3dColor.from_argb_int(255, 0, 255, 0),
            True,
            1.0,
            Sp3dColor.from_argb_int(255, 0, 255, 0),
        )
    ],
    [],
)

Object Operations

# Move
sp3d_obj.move(Sp3dV3D(1, 0, 0))

# Rotate
sp3d_obj.rotate(Sp3dV3D(0, 1, 0), 45 * math.pi / 180)

# Vertex manipulation
# You can do many other things with the Sp3dV3D features.
sp3d_obj.vertices[0] += Sp3dV3D(1, 0, 0)

Convert to Dictionary (for JSON serialization)

import json

sp3d_obj_dict = sp3d_obj.to_dict()
json_str = json.dumps(sp3d_obj_dict)

Restore from Dictionary

restored_dict = json.loads(json_str)
restored = Sp3dObj.from_dict(restored_dict)

Color

Unlike the Dart version which uses Flutter's Color class, this package provides Sp3dColor. Colors are stored as ARGB float values in the range [0.0, 1.0].

from simple_3d import Sp3dColor

# From integer ARGB values (0-255)
color = Sp3dColor.from_argb_int(255, 0, 255, 0)   # opaque green

# From float ARGB values (0.0-1.0)
color = Sp3dColor(1.0, 0.0, 1.0, 0.0)

# Convert back to integer ARGB
a, r, g, b = color.to_argb_int()

Sp3dV3D — 3D Vector

from simple_3d import Sp3dV3D
import math

v1 = Sp3dV3D(1.0, 0.0, 0.0)
v2 = Sp3dV3D(0.0, 1.0, 0.0)

# Arithmetic
v3 = v1 + v2
v4 = v1 * 2.0
v5 = v3 / 2.0

# Length and normalization
length = v1.len()
unit = v1.nor()

# Dot and cross products
d = Sp3dV3D.dot(v1, v2)
c = Sp3dV3D.cross(v1, v2)

# Rotation (around a normalized axis)
z_axis = Sp3dV3D(0, 0, 1)
rotated = v1.rotated(z_axis, math.pi / 2)   # returns new vector
v1.rotate(z_axis, math.pi / 2)              # mutates in place

# Signed angle
angle = Sp3dV3D.signed_angle(v1, v2, z_axis)   # radians, with sign

Format Name

Simple 3D Format

File Extension

.sp3d

MIME Type (Temporary)

model/x.sp3d

Suitable

Science (e.g., physics calculations), simple games, etc.

Not Suitable

Advanced graphics.

Structure (Decoded Object)

• Sp3dObj
  • vertices: list of Sp3dV3D
  • fragments: list of Sp3dFragment
    • faces: list of Sp3dFace
      • vertex_index_list: list of int — counterclockwise from upper-left
      • material_index: int or None
    • is_particle: bool
    • r: float — radius for particle type
    • physics: Sp3dPhysics or None - An object with multiple variables used in physical calculations.
    • is_touchable: bool — if False, excluded from touch calculations
    • name: str or None
    • option: dict or None — app-specific optional attributes (must be JSON-serializable)
  • materials: list of Sp3dMaterial
    • bg: Sp3dColor — ARGB background color
    • is_fill: bool — if False, stroke line only
    • stroke_width: float
    • stroke_color: Sp3dColor — ARGB stroke color
    • image_index: int or None — fills the face with the specified image when not None
    • texture_coordinates: list of (float, float) or None — 3 or 6 points (square = two triangles)
    • name: str or None
    • option: dict or None
  • images: list of bytes — PNG data
  • id: str or None
  • name: str or None
  • author: str or None
  • physics: Sp3dPhysics or None - An object with multiple variables used in physical calculations.
  • option: dict or None
  • layer_num: int — drawing priority in the depth direction
  • draw_mode: EnumSp3dDrawMode — drawing mode for renderers

Parameter Note

If you use Sp3dObj to calculate a large number of atoms, consider using the is_particle flag and r (radius). Each atom has one vertex when calculated or saved, and you can draw a sphere only when rendering.

JSON Compatibility with Dart Version

to_dict() / from_dict() produce output compatible with Dart version 21 and later (camelCase keys). For compatibility with older versions (≤ v20, snake_case keys), use to_dict_v14(). from_dict() automatically detects the version and calls the appropriate loader.

License

This software is released under the MIT License. See the LICENSE file for details.

Trademarks

• “Dart” and “Flutter” are trademarks of Google LLC.
  This package is not developed or endorsed by Google LLC.

• “Python” is a trademark of the Python Software Foundation.
  This package is not affiliated with the Python Software Foundation.

• GitHub and the GitHub logo are trademarks of GitHub, Inc.
  This package is not affiliated with GitHub, Inc.