trueform — NumPy for Geometry

Fast and exact mesh booleans, spatial queries, arrangements, registration, and remeshing on NumPy arrays. NumPy in, NumPy out.

Read the article: The STL for Geometry — What the STL philosophy of separating algorithms from data looks like when applied to geometry.

polydera.com/trueform | Documentation | ▶ Try it live

Installation

pip install trueform

Quick Tour

Primitives — typed NumPy arrays, single or batched:

import numpy as np
import trueform as tf

triangle = tf.Triangle(a=[0, 0, 0], b=[1, 0, 0], c=[0, 1, 0])
segment = tf.Segment([[0, 0, 0], [1, 1, 1]])
ray = tf.Ray(origin=[0.2, 0.2, -1], direction=[0, 0, 1])

# Add a leading dimension for batches
pts = tf.Point(np.random.rand(1000, 3).astype(np.float32))
segs = tf.Segment(start=np.random.rand(500, 3), end=np.random.rand(500, 3))

Meshes are created from NumPy arrays or read from files:

points = np.array([
    [0, 0, 0], [1, 0, 0], [0, 1, 0], [0, 0, 1]
], dtype=np.float32)
faces = np.array([
    [0, 1, 2], [0, 2, 3], [0, 3, 1], [1, 3, 2]
], dtype=np.int32)

mesh = tf.Mesh(faces, points)

# Or read from file
mesh = tf.Mesh(*tf.read_stl("model.stl"))

Queries — same functions for any combination. Batches broadcast:

# Batch × Primitive — distance field to a plane
plane = tf.Plane(normal=[0, 0, 1], offset=0.0)
scalars = tf.distance(pts, plane)                    # shape (1000,)

# Batch × Form — closest point on mesh for each segment
ids, dist2s, closest = tf.neighbor_search(mesh, segs) # 3 arrays, shape (500,)

# Single × Single
dist2, pt_a, pt_b = tf.closest_metric_point_pair(triangle, segment)

if (t := tf.ray_cast(ray, triangle)) is not None:
    hit_point = ray.origin + t * np.array(ray.direction)

Boolean operations:

(result_faces, result_points), labels, face_labels = tf.boolean_union(mesh0, mesh1)

# With intersection curves
(result_faces, result_points), labels, face_labels, (paths, curve_points) = tf.boolean_union(
    mesh0, mesh1, return_curves=True
)

Remeshing:

# Decimate to 50%
dec_faces, dec_points = tf.decimated(mesh, 0.5)

# Isotropic remesh to uniform edge lengths
dec_mesh = tf.Mesh(dec_faces, dec_points)
mel = tf.mean_edge_length(dec_mesh)
rem_faces, rem_points = tf.isotropic_remeshed(dec_mesh, mel)

→ Full documentation covers mesh analysis, topology, isocontours, curvature, and more.

Examples

• Guided Examples — Step-by-step walkthroughs for spatial queries, topology, and booleans
• VTK Integration — Interactive VTK applications

Run examples locally:

git clone https://github.com/polydera/trueform.git
cd trueform/python/examples
pip install vtk  # for interactive examples
python vtk/collision.py mesh.stl

Blender Integration

Cached meshes with automatic dirty-tracking for live preview add-ons. See Blender docs.

Benchmarks

Apple M4 Max, 16 threads, Clang -O3. Full methodology

License

Dual-licensed: PolyForm Noncommercial 1.0.0 for noncommercial use, commercial licenses available.

Contributing

See CONTRIBUTING.md and open issues.

Citation

@software{trueform2025,
    title={trueform: the CSG Engine},
    author={Sajovic, {\v{Z}}iga and {et al.}},
    organization={Polydera},
    year={2025},
    url={https://github.com/polydera/trueform}
}