`ConstructiveGeometry.jl`

Documentation

This package provides tools for describing 3d objects in Julia. For example, this is the Julia code used to draw the logo of this page:

```
using ConstructiveGeometry
using CairoMakie
using Colors
hexagon = polygon([[cospi(t/3),sinpi(t/3)] for t in 0:5])
c1, c2, c3 = colorant"#cb3c33", colorant"#9558b2", colorant"#389826"
bolt = linear_extrude(5)*(8*hexagon) ∪ cylinder(15,4) ∪
rotate_extrude(7*360, slide=14)*translate([1,0])*square(4,1)
m = union(c1*bolt, [20,0,0]+c2*bolt, [10,17,0]+c3*bolt)
save("logo.png", Makie.plot(m))
```

# Overview

Drawing an object is generally done in two steps. First, an abstract, “ideal” geometric object (in either two or three dimensions) is defined using the following constructions:

- primitive geometric objects, such as cubes, spheres, explicit polygons, etc.;
- geometric transformations acting on one object, such as (invertible) affine transformations, extrusions, projections, color-change, etc.;
- CSG operations combining several objects, such as boolean operations or Minkowski sum.

Such an abstract object is stored as a tree with primitive objects as leaves:

```
julia> display(bolt)
union
├─ Prism
│ └─ AffineTransform
│ └─ ShapeMesh # 1 polygon(s), 6 vertices
├─ Prism
│ └─ Circle
└─ Revolution
└─ AffineTransform
└─ Square
```

Any geometric object defined in this way can then be instantiated as an explicit mesh. The mesh may be visualized directly within Julia (using `Makie`

) or exported in several formats, including as an STL (for 3d objects) or SVG (for 2d objects) file.

The documentation about extending `ConstructiveGeometry`

also contains some explanations about the internals.