I. Introduction

BRL-CAD is a free, open-source 3D modeling (CAD) system built around Constructive Solid Geometry (CSG). You can use it to build solid objects for machines by combining simple shapes (primitives) into complex parts using boolean operations: union, difference, and intersection. BRL-CAD is geometry-first CAD, so it’s useful for physics, engineering design, computer graphics, and simulation/computational geometry.

II. Outline

  • What BRL-CAD is
    • An open-source CAD for solid modeling, and not just for joining surfaces.
    • Good for learning how 3D objects are built from simple shapes.
    • Includes ray tracing for rendering and geometry checking
  • Core terms
    • Primitives: box, sphere, cylinder, cone, torus, etc.
    • Boolean Operations:
      • Union (A ∪ B): combine solids
      • Difference (A − B): subtract one solid from another (cuts/holes)
      • Intersection (A ∩ B): keep only the overlap
    • CSG tree: Defining the primitives like variables and the operations is the function using the inputs.
    • Transforms: move/rotate/scale parts precisely
  • What you can do with it
    • Design 3D parts
    • Make holes, slots, and cutouts accurately
    • Verifying Geometry and Models
  • How it connects to STEM
    • Physics: shape matters for things like paths, line-of-sight, and areas/volumes
    • Engineering: design parts that fit together and measure correctly
    • Computer Science: 3D graphics ideas, ray tracing, and automation/scripting
    • Math: coordinates, distances, angles, and “combining shapes” logic

III. Downloads & Documentation

IV. Video Series

V. See Also