A comprehensive Euclidean geometry package, inspired by the LaTeX tkz-euclide package.

Note: This package is a port of the LaTeX tkz-euclide package. We are deeply grateful to Alain Matthes for creating the original tkz-euclide package, without which this Typst port would have been impossible. This package aims to implement the complete feature set of the tkz-euclide package; we are not there yet.

Development Note: This package was coded entirely by Claude Code Opus 4.5 and Codex. Nevertheless, I have spent lots of time and energy in the following feedback loop: prompting, reviewing, testing and designing. Any mistakes or bugs are my own.

⚠️ Early Development Status

This package is by no means definitive. Improvements and features are planned and will be implemented over time. The API may change as the package evolves.

This package is being developed. Expect:

• Bug fixes and improvements
• New features and triangle centers
• API refinements
• Performance optimizations

Dependencies

• CeTZ v0.5.2

Changelog

0.2.0 - 2026-07-07

Added

• Automatic label placement (collision avoidance), on by default: labels are placed as close as possible to the requested anchor while avoiding drawn segments, circles, point markers and other labels. Labels without an explicit position are fully automatic (labels: true, or "auto" per label). The engine prefers the requested side (pushed slightly farther out), then a 45° lean, then the opposite side — a crowded row alternates its labels above/below the line instead of piling them up on one side. A label is accepted as soon as its text is clear: thin geometry may run through its padding, and free-floating candidates at 16 fine directions nestle labels into open wedges at hub points (centroid, incenter…), so they stay snug instead of drifting away. Guarantees: a label is always strictly closer to its own point than to any other point (assoc-factor); in tight clusters the point-to-text gap shrinks to 60% so labels hug their point. The font is reduced (85%, then 70%) only when nothing calm fits at full size — and then all labels of the figure share the same scale (allow-shrink: false forbids it entirely). Global switch ctz-label-avoid(false), per-label avoid: false, tunable via ctz-label-avoid((rings: ..., shrink: ..., assoc-factor: ...)). Angle labels slide along the bisector to stay clear.
• Precise label placement: direction tokens with numeric offsets pin a label exactly where asked (collision engine off for it): labels: (A: "above+1.2 left+0.5", B: "top+0.8") — offsets in canvas units, top/bottom/up/down accepted as aliases, negative amounts flip the direction. Equivalent dictionary form: (pos: "above left", offset: (-0.5, 1.2), avoid: false).
• Exterior angle support (#2): ctz-draw-angle(..., angle-type: "reflex") (explementary) and angle-type: "supplementary" (exterior).
• ctz-def-golden(..., inside: false) for the external golden section.
• ctz-def-translate accepts a pair of point names as the vector.
• ctz-draw(points: ..., shape: ..., size: ..., color: ...) style overrides.
• ctz-style(angle: (...)) is now honored by ctz-draw-angle.
• Greek point names render as symbols in labels (“alpha” → α, “Omega1” → Ω1).

Fixed

• Arc rendering (#4): arcs, sectors, semicircles and compass marks were drawn offset by one radius (cetz anchors arcs at their start point, not their center) and with mirrored start/end angles.
• Systemic calc.atan2 argument-order bug affecting slope calculations, tangent points from an external point, sector/semicircle angles, the german-style right-angle mark, sloped segment labels, ellipse projections/tangents and automatic label placement.
• cetz version conflict (#1): upgraded to CeTZ 0.5.2 — no more conflict when combining ctz-euclide with cetz-plot or your own cetz import, in any import order.
• ctz-def-golden crashed on every call.
• ctz-draw(name, sketchy: true) crashed on named lines and polygons.
• ctz-def-excenter/ctz-def-excircle vertex is now case-insensitive (the default silently computed the excenter opposite C).
• Feuerbach point returned the incenter instead of the tangency point.
• Tangent points from an external point used asin instead of acos.
• Duplicate labels for the same point (same content) are now drawn only once.
• Labels for point names longer than 5 characters were silently dropped.
• Grids and axes no longer drop their last line/tick to float rounding.
• Internal module names (util, draw, circle, …) are no longer leaked into your document by the wildcard import (the cetz binding is still exported on purpose, for import cetz.draw: *).
• ctz-version is now read from typst.toml (was stuck at 0.1.0).

0.1.5

• Main-levée (hand-drawn/sketchy) style, including sketchy: true on ctz-draw
• Global style configuration variables for colors, point shapes, sizes, and mark widths
• Canvas-level clipping via ctz-canvas(clip-canvas: ...) with line/segment clipping
• Labels now render in math font by default
• Expanded docs and gallery examples for styling, main-levée, and clipping

0.1.0

• Initial public release
• Core Euclidean constructions, transformations, intersections
• Drawing utilities with unified ctz-draw
• Conics, parabola helpers, and inversion features
• Manual PDF and gallery examples

Gallery

Click on an image to see the source code.

Triangle Centers	Nine-Point Circle	Regular Pentagon
Inscribed Angle	Apollonius Circle	Orthocenter
Equilateral Triangle	Perpendicular Bisectors	Thales' Theorem
Inversion	Inversion Packing	Inversion Ladder
Automatic Label Placement

Documentation

📖 Complete Manual (PDF) - Comprehensive documentation with examples and gallery

The manual includes:

• Detailed API reference for all functions
• Step-by-step examples and tutorials
• Gallery of advanced geometric constructions
• Complete feature overview

Deploy Checklist

1. Switch docs to local imports and compile:

./scripts/use-local-docs.sh
typst compile docs/manual.typ docs/manual.pdf

2. Rebuild gallery images (SVG):

./scripts/build-gallery.sh

Contributions Welcome

Contributions, bug reports, feature requests, and feedback are warmly welcomed! Please feel free to:

• Open issues on the repository
• Submit pull requests
• Share examples and use cases
• Report bugs or suggest improvements

Quick Start

#import "@preview/ctz-euclide:0.2.0": *

#ctz-canvas({
  import cetz.draw: *

  ctz-init()
  ctz-style(point: (shape: "cross", size: 0.1, stroke: black + 1.5pt))

  // Define points
  ctz-def-points(A: (0, 0), B: (4, 0), C: (2, 3))

  // Draw triangle
  ctz-draw-line("A", "B", "C", "A", stroke: black)

  // Mark points and add labels
  ctz-draw-points("A", "B", "C")
  ctz-draw-labels("A", "B", "C",
    A: "below left", B: "below right", C: "above")

  // Mark an angle
  ctz-draw-angle("A", "B", "C", label: $alpha$, radius: 0.5)
})

Naming notes:

• All public functions are prefixed with ctz- to avoid conflicts.
• Point creation and drawing use ctz-def-points and ctz-draw-points.
• Other constructors use ctz-def-*, and drawing utilities use ctz-draw-*.

Features

• Point Constructions: Define points by coordinates, transformations, intersections
• Transformations: Rotation, reflection, translation, scaling, projection
• Intersections: Line-line, line-circle, circle-circle
• Triangle Centers: Centroid, circumcenter, incenter, orthocenter, and many more
• Special Triangles: Medial, orthic, intouch triangles, Thales’ triangle
• Drawing: Points, lines, angles, circles, arcs
• Inversion: Invert points and objects about a circle
• Conics: Ellipses and parabolas, including focus/directrix and focus/parameter forms
• Parabolas: Directrix helpers, tangents, and projectile trajectories
• Projections: Point projections and descriptive-geometry helpers
• Unified Drawing: ctz-draw() works with any object type (points, lines, circles, polygons)
• Object Duplication: ctz-duplicate() duplicates any geometric object
• Angle Marking: With customizable labels and positioning
• Point Styles: Multiple marker types (cross, dot, circle, plus, etc.)

Basic Features

Point Definition

// Define points
ctz-def-points(A: (0, 0), B: (3, 0), C: (1.5, 2.5))

Transformations

// Rotation
ctz-def-rotation("B", "A", "O", 60)  // Rotate A around O by 60°

// Reflection
ctz-def-reflect("C", "A", "P", "Q")  // Reflect A across line PQ

// Translation
ctz-def-translate("D", "A", (2, 3))  // Translate A by vector (2, 3)

Intersections

// Line-line intersection
ctz-def-ll("E", ("A", "B"), ("C", "D"))

// Line-circle intersection
ctz-def-lc(("F", "G"), ("A", "B"), ("O", "P"))

// Circle-circle intersection
ctz-def-cc(("H", "I"), ("O1", "P1"), ("O2", "P2"))

Triangle Centers

// Centroid
ctz-def-centroid("G", "A", "B", "C")

// Circumcenter
ctz-def-circumcenter("O", "A", "B", "C")

// Incenter
ctz-def-incenter("I", "A", "B", "C")

// Orthocenter
ctz-def-orthocenter("H", "A", "B", "C")

Drawing

// Draw points
ctz-draw-points("A", "B", "C")

// Add labels
ctz-draw-labels("A", "B", "C",
  A: "below left", B: "below right", C: "above")

// Mark angles
ctz-draw-angle("B", "A", "C", label: $alpha$, radius: 0.6)

Paths and Arrows

// TikZ-like per-segment tips
ctz-draw-path("A--B->C|-|D", stroke: black)

Supported connectors: --, ->, <-, <->, |-|, |->, <-|. By default, points (small dots) and labels (below) are drawn. Override with {...} in the path: "A{below}--B{below}->C{above}|-|D{below}". You can customize point appearance with point-style and point-color, or disable with points: false.

Segment Measurements

ctz-draw-measure-segment("A", "B", label: $5$, offset: 0.3, side: "left")

Advanced Features

The package includes many advanced features:

• Extended triangle centers (Euler, Lemoine, Nagel, Gergonne, Spieker, Feuerbach, etc.)
• Special triangle constructions (medial, orthic, intouch, excentral, tangential)
• Thales’ Triangle: ctz-def-thales-triangle() creates right triangles inscribed in circles
• Circle operations (tangents, radical axis, Apollonius circles)
• Point constructions (midpoint, golden ratio, barycentric coordinates)
• Geometric transformations (symmetry, inversion)
• Polymorphic Transformations: ctz-def-rotation() works on all object types (points, lines, circles, polygons)
• Drawing utilities (polygons, segments, arcs, sectors)
• Marking utilities (segment marks, right angles, angle fills)

See the complete documentation for details on all features.

Acknowledgments

This package is a port of the LaTeX tkz-euclide package created by Alain Matthes. The original tkz-euclide package has been an invaluable resource for geometric constructions in LaTeX, and this port aims to bring similar functionality to the Typst ecosystem.

License

MIT License - see LICENSE file for details.

Changelog

[0.1.5] - 2026-01-27

Canvas Clipping

• Canvas-level clipping via ctz-canvas(clip-canvas: ...)
• Line/segment drawing respects canvas clip bounds (circles/shapes unchanged)

Main-levée (Hand-drawn Style)

• Sketchy drawing mode for lines/circles/ellipses/polygons/rects/arcs
• ctz-draw(..., sketchy: true) support

Math Labels

• Labels now render in mathematical font by default

Global Styling

• Centralized, user-configurable defaults for colors, point sizes/shapes, and mark widths
• Manual updates documenting global style configuration

[0.1.0] - 2026-01-21

Initial Release

• Core geometric constructions (points, lines, circles)
• Point transformations (rotation, reflection, translation, scaling)
• Intersection algorithms (line-line, line-circle, circle-circle)
• Basic triangle centers (centroid, circumcenter, incenter, orthocenter)
• Extended triangle centers (Euler, Lemoine, Nagel, Gergonne, Spieker, etc.)
• Special triangle constructions
• Angle marking with customizable labels
• Multiple point styles
• Drawing utilities
• Built on CeTZ v0.5.2