feat: add generate_primitives.py for GLTF model generation of cube and sphere
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MayaTheShy
232
tools/generate_primitives.py
Executable file
232
tools/generate_primitives.py
Executable file
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#!/usr/bin/env python3
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"""
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Generate simple GLTF primitive models for Starworld entity rendering.
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Requires: pip install pygltflib numpy
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"""
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import numpy as np
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from pygltflib import *
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import struct
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import os
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from pathlib import Path
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def create_cube_gltf(output_path):
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"""Create a 1x1x1 cube centered at origin"""
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# Cube vertices (8 vertices)
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vertices = np.array([
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[-0.5, -0.5, -0.5], # 0
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[ 0.5, -0.5, -0.5], # 1
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[ 0.5, 0.5, -0.5], # 2
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[-0.5, 0.5, -0.5], # 3
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[-0.5, -0.5, 0.5], # 4
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[ 0.5, -0.5, 0.5], # 5
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[ 0.5, 0.5, 0.5], # 6
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[-0.5, 0.5, 0.5], # 7
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], dtype=np.float32)
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# Cube indices (12 triangles, 36 indices)
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indices = np.array([
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# Front face
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0, 1, 2, 0, 2, 3,
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# Back face
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5, 4, 7, 5, 7, 6,
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# Top face
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3, 2, 6, 3, 6, 7,
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# Bottom face
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4, 5, 1, 4, 1, 0,
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# Right face
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1, 5, 6, 1, 6, 2,
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# Left face
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4, 0, 3, 4, 3, 7,
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], dtype=np.uint16)
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# Normals (per-face normals repeated for each vertex of triangle)
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normals = np.array([
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# Front
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[0, 0, -1], [0, 0, -1], [0, 0, -1], [0, 0, -1], [0, 0, -1], [0, 0, -1],
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# Back
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[0, 0, 1], [0, 0, 1], [0, 0, 1], [0, 0, 1], [0, 0, 1], [0, 0, 1],
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# Top
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[0, 1, 0], [0, 1, 0], [0, 1, 0], [0, 1, 0], [0, 1, 0], [0, 1, 0],
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# Bottom
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[0, -1, 0], [0, -1, 0], [0, -1, 0], [0, -1, 0], [0, -1, 0], [0, -1, 0],
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# Right
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[1, 0, 0], [1, 0, 0], [1, 0, 0], [1, 0, 0], [1, 0, 0], [1, 0, 0],
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# Left
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[-1, 0, 0], [-1, 0, 0], [-1, 0, 0], [-1, 0, 0], [-1, 0, 0], [-1, 0, 0],
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], dtype=np.float32)
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# Create binary data
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vertices_binary = vertices.tobytes()
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indices_binary = indices.tobytes()
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# Build GLTF
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gltf = GLTF2(
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scene=0,
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scenes=[Scene(nodes=[0])],
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nodes=[Node(mesh=0)],
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meshes=[
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Mesh(primitives=[
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Primitive(
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attributes=Attributes(POSITION=0),
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indices=1,
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)
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])
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],
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accessors=[
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Accessor(
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bufferView=0,
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componentType=FLOAT,
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count=len(vertices),
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type=VEC3,
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max=vertices.max(axis=0).tolist(),
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min=vertices.min(axis=0).tolist(),
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),
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Accessor(
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bufferView=1,
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componentType=UNSIGNED_SHORT,
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count=len(indices),
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type=SCALAR,
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),
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],
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bufferViews=[
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BufferView(
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buffer=0,
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byteOffset=0,
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byteLength=len(vertices_binary),
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target=ARRAY_BUFFER,
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),
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BufferView(
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buffer=0,
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byteOffset=len(vertices_binary),
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byteLength=len(indices_binary),
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target=ELEMENT_ARRAY_BUFFER,
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),
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],
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buffers=[
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Buffer(byteLength=len(vertices_binary) + len(indices_binary))
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],
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)
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gltf.set_binary_blob(vertices_binary + indices_binary)
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gltf.save(output_path)
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print(f"Created cube: {output_path}")
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def create_sphere_gltf(output_path, segments=32, rings=16):
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"""Create a UV sphere"""
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vertices = []
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normals = []
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indices = []
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# Generate vertices
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for ring in range(rings + 1):
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theta = ring * np.pi / rings
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sin_theta = np.sin(theta)
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cos_theta = np.cos(theta)
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for seg in range(segments + 1):
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phi = seg * 2 * np.pi / segments
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sin_phi = np.sin(phi)
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cos_phi = np.cos(phi)
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x = cos_phi * sin_theta
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y = cos_theta
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z = sin_phi * sin_theta
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vertices.append([x * 0.5, y * 0.5, z * 0.5]) # radius 0.5
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normals.append([x, y, z])
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# Generate indices
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for ring in range(rings):
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for seg in range(segments):
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first = ring * (segments + 1) + seg
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second = first + segments + 1
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indices.extend([first, second, first + 1])
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indices.extend([second, second + 1, first + 1])
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vertices = np.array(vertices, dtype=np.float32)
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normals = np.array(normals, dtype=np.float32)
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indices = np.array(indices, dtype=np.uint16)
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vertices_binary = vertices.tobytes()
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normals_binary = normals.tobytes()
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indices_binary = indices.tobytes()
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gltf = GLTF2(
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scene=0,
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scenes=[Scene(nodes=[0])],
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nodes=[Node(mesh=0)],
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meshes=[
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Mesh(primitives=[
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Primitive(
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attributes=Attributes(POSITION=0, NORMAL=1),
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indices=2,
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)
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])
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],
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accessors=[
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Accessor(
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bufferView=0,
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componentType=FLOAT,
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count=len(vertices),
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type=VEC3,
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max=vertices.max(axis=0).tolist(),
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min=vertices.min(axis=0).tolist(),
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),
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Accessor(
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bufferView=1,
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componentType=FLOAT,
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count=len(normals),
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type=VEC3,
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),
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Accessor(
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bufferView=2,
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componentType=UNSIGNED_SHORT,
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count=len(indices),
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type=SCALAR,
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),
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],
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bufferViews=[
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BufferView(
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buffer=0,
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byteOffset=0,
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byteLength=len(vertices_binary),
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target=ARRAY_BUFFER,
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),
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BufferView(
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buffer=0,
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byteOffset=len(vertices_binary),
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byteLength=len(normals_binary),
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target=ARRAY_BUFFER,
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),
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BufferView(
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buffer=0,
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byteOffset=len(vertices_binary) + len(normals_binary),
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byteLength=len(indices_binary),
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target=ELEMENT_ARRAY_BUFFER,
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),
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],
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buffers=[
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Buffer(byteLength=len(vertices_binary) + len(normals_binary) + len(indices_binary))
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],
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)
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gltf.set_binary_blob(vertices_binary + normals_binary + indices_binary)
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gltf.save(output_path)
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print(f"Created sphere: {output_path}")
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if __name__ == "__main__":
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# Create output directory
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cache_dir = Path.home() / ".cache" / "starworld" / "primitives"
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cache_dir.mkdir(parents=True, exist_ok=True)
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# Generate primitives
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create_cube_gltf(str(cache_dir / "cube.glb"))
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create_sphere_gltf(str(cache_dir / "sphere.glb"))
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print(f"\n✓ Primitive models generated in: {cache_dir}")
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print(f" - cube.glb")
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print(f" - sphere.glb")
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