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generate_static_bodies.py

Display and export static OBJ / unskinned glTF/FBX bodies

timfa Grok Bot · pushed by timfa · 7 days ago

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generate_static_bodies.py 6.4 KiB Download Raw

1	#!/usr/bin/env python3
2	"""Generate the static (unskinned) male test body fixtures.
3
4	Same procedural boxes as scripts/generate_test_bodies.py in their bind pose,
5	but WITHOUT a skin or skeleton:
6
7	* static-body-male.obj + .mtl + static-body-albedo.png (OBJ/MTL/PNG). Boxes
8	whose center is above 1.2 m sample the top (red) half of the texture,
9	lower boxes the bottom (blue) half, so UV orientation is testable.
10	* static-body-male.glb: unskinned glTF. The mesh sits under a parent node
11	(translation + uniform scale 2) and a child node (rotation 90 deg about Y);
12	vertices/normals are stored pre-transformed so the baked world geometry
13	equals the skinned body's bind pose. One node animation is included and
14	must NOT be applied by the static loader.
15
16	Run from the repository root:
17
18	python3 scripts/generate_static_bodies.py
19	"""
20
21	from __future__ import annotations
22
23	import math
24	import struct
25	import sys
26	import zlib
27	from pathlib import Path
28
29	sys.path.insert(0, str(Path(__file__).resolve().parent))
30	import generate_test_bodies as gen # noqa: E402
31
32	OUT = Path("tests/fixtures/bodies/static")
33	PARENT_T = (0.25, -0.1, 0.4)
34	PARENT_S = 2.0
35	RED = (220, 40, 30, 255)
36	BLUE = (30, 60, 220, 255)
37
38
39	def png_rgba(width: int, height: int, rows: list[list[tuple[int, int, int, int]]]) -> bytes:
40	raw = b"".join(b"\x00" + bytes(c for px in row for c in px) for row in rows)
41	def chunk(kind: bytes, data: bytes) -> bytes:
42	return struct.pack(">I", len(data)) + kind + data + struct.pack(">I", zlib.crc32(kind + data) & 0xFFFFFFFF)
43	ihdr = struct.pack(">IIBBBBB", width, height, 8, 6, 0, 0, 0)
44	return b"\x89PNG\r\n\x1a\n" + chunk(b"IHDR", ihdr) + chunk(b"IDAT", zlib.compress(raw, 9)) + chunk(b"IEND", b"")
45
46
47	def boxes(sex: str):
48	"""Yield (triangles, face normals, uv v) per box in world bind pose."""
49	spec = gen.skeleton(sex)
50	for joint_index, (name, _p, _l, size) in enumerate(spec):
51	center = gen.world_translation(spec, name)
52	positions: list[float] = []
53	indices: list[int] = []
54	gen.add_box(positions, indices, [], [], center, size, joint_index)
55	corners = [tuple(positions[i:i + 3]) for i in range(0, len(positions), 3)]
56	tris = [tuple(indices[i:i + 3]) for i in range(0, len(indices), 3)]
57	v = 0.85 if center[1] > 1.2 else 0.15
58	yield corners, tris, v
59
60
61	def face_normal(a, b, c):
62	u = [b[i] - a[i] for i in range(3)]
63	w = [c[i] - a[i] for i in range(3)]
64	n = [u[1] * w[2] - u[2] * w[1], u[2] * w[0] - u[0] * w[2], u[0] * w[1] - u[1] * w[0]]
65	length = math.sqrt(sum(x * x for x in n))
66	return tuple(x / length for x in n)
67
68
69	def write_obj(sex: str) -> None:
70	lines = [
71	"# Static CC0 test body (no skeleton). Generated by scripts/generate_static_bodies.py",
72	"mtllib static-body-male.mtl",
73	"usemtl body",
74	]
75	vt = ["vt 0.5 0.85", "vt 0.5 0.15"]
76	lines += vt
77	v_count = 0
78	n_count = 0
79	faces = []
80	for corners, tris, v in boxes(sex):
81	for c in corners:
82	lines.append("v %.6f %.6f %.6f" % c)
83	uv = 1 if v > 0.5 else 2
84	for t in tris:
85	n = face_normal(corners[t[0]], corners[t[1]], corners[t[2]])
86	lines.append("vn %.6f %.6f %.6f" % n)
87	n_count += 1
88	faces.append("f " + " ".join(f"{v_count + i + 1}/{uv}/{n_count}" for i in t))
89	v_count += len(corners)
90	lines += faces
91	(OUT / "static-body-male.obj").write_text("\n".join(lines) + "\n")
92	(OUT / "static-body-male.mtl").write_text(
93	"# CC0 static test body material\nnewmtl body\nKd 1.0 1.0 1.0\nd 1.0\nmap_Kd static-body-albedo.png\n"
94	)
95	rows = [[RED] * 4, [RED] * 4, [BLUE] * 4, [BLUE] * 4]
96	(OUT / "static-body-albedo.png").write_bytes(png_rgba(4, 4, rows))
97
98
99	def rot_y(deg: float, p):
100	a = math.radians(deg)
101	c, s = math.cos(a), math.sin(a)
102	return (c * p[0] + s * p[2], p[1], -s * p[0] + c * p[2])
103
104
105	def write_glb(sex: str) -> None:
106	positions: list[float] = []
107	normals: list[float] = []
108	indices: list[int] = []
109	for corners, tris, _v in boxes(sex):
110	for t in tris:
111	a, b, c = (corners[i] for i in t)
112	n = face_normal(a, b, c)
113	for p in (a, b, c):
114	local = tuple((p[i] - PARENT_T[i]) / PARENT_S for i in range(3))
115	positions.extend(rot_y(-90.0, local))
116	normals.extend(rot_y(-90.0, n))
117	indices.append(len(indices))
118	blob = gen.Blob()
119	index_acc = blob.add_u16(indices, "SCALAR", len(indices))
120	pmin, pmax = gen.vec_min_max(positions, 3)
121	pos_acc = blob.add_f32(positions, "VEC3", len(positions) // 3, pmin, pmax)
122	nrm_acc = blob.add_f32(normals, "VEC3", len(normals) // 3)
123	times = blob.add_f32([0.0, 1.0], "SCALAR", 2, [0.0], [1.0])
124	half = math.radians(45.0)
125	rot_out = blob.add_f32([0, 0, 0, 1, 0, math.sin(half), 0, math.cos(half)], "VEC4", 2)
126	half90 = math.radians(45.0)
127	gltf = {
128	"asset": {
129	"version": "2.0",
130	"generator": "scripts/generate_static_bodies.py",
131	"extras": {"testAsset": True, "license": "CC0-1.0", "skin": False},
132	},
133	"scene": 0,
134	"scenes": [{"name": "static-body", "nodes": [0]}],
135	"nodes": [
136	{"name": "static-root", "translation": list(PARENT_T), "scale": [PARENT_S] * 3, "children": [1]},
137	{"name": "static-body-mesh", "rotation": [0.0, math.sin(half90), 0.0, math.cos(half90)], "mesh": 0},
138	],
139	"meshes": [{"name": "static-body", "primitives": [{
140	"attributes": {"POSITION": pos_acc, "NORMAL": nrm_acc},
141	"indices": index_acc, "material": 0}]}],
142	"materials": [{"name": "static-body", "pbrMetallicRoughness": {
143	"baseColorFactor": [0.45, 0.55, 0.70, 1.0], "metallicFactor": 0.0, "roughnessFactor": 1.0}}],
144	"animations": [{"name": "spin-not-applied", "channels": [{"sampler": 0, "target": {"node": 0, "path": "rotation"}}],
145	"samplers": [{"input": times, "output": rot_out, "interpolation": "LINEAR"}]}],
146	"buffers": [{"byteLength": len(blob.data)}],
147	"bufferViews": blob.views,
148	"accessors": blob.accessors,
149	}
150	(OUT / "static-body-male.glb").write_bytes(gen.pack_glb(gltf, bytes(blob.data)))
151
152
153	def main() -> None:
154	OUT.mkdir(parents=True, exist_ok=True)
155	write_obj("male")
156	write_glb("male")
157	for p in sorted(OUT.iterdir()):
158	print(f"wrote {p} ({p.stat().st_size} bytes)")
159
160
161	if __name__ == "__main__":
162	main()