This project was created as part of the 42 curriculum by rgregori, tlavared.
A ray tracer written from scratch in pure C, rendering 3D scenes with realistic Phong lighting.
The following examples demonstrate miniRT's rendering mandatory and bonus features.
miniRT is a ray tracer built from scratch in pure C as a project for 42 School. It renders 3D scenes described in .rt text files, producing images with realistic lighting using the Phong reflection model.
For each pixel on the screen, a ray is cast from the camera into the scene. When it intersects an object, the color is computed based on ambient, diffuse, and specular lighting, shadows, and material properties:
P(t) = origin + t * direction
The visible object at each pixel is the one with the smallest positive t along the ray.
Stack: C · MLX42 · pthreads · CMake · Make
School: 42 São Paulo
Status: ✅ Completed — mandatory + all bonus items implemented
| Feature | Mandatory | Bonus |
|---|---|---|
| Sphere, Plane, Cylinder | ✅ | ✅ |
| Cone | — | ✅ |
| Phong Lighting (ambient, diffuse, specular) | ✅ | ✅ |
| Shadows (shadow rays) | ✅ | ✅ |
| Multiple lights with accumulation | ✅ | ✅ |
| MSAA Anti-aliasing | — | ✅ |
| Recursive Reflection | — | ✅ |
| Per-object material properties (ks, kd, ka, shininess, reflectivity) | — | ✅ |
| Procedural Checkerboard | — | ✅ |
| Bump mapping (procedural via sine + PNG) | — | ✅ |
| Multi-threading with pthreads | — | ✅ |
| Sky color (miss ray) | — | ✅ |
| Resizable window | ✅ | ✅ |
Before building, install the required system libraries.
Ubuntu / Debian:
sudo apt update
sudo apt install -y build-essential cmake libglfw3-dev libgl1-mesa-devmacOS (with Homebrew):
brew install cmake glfwNote:
makeandcc(gcc or clang) are included inbuild-essentialon Linux and in Xcode Command Line Tools on macOS (xcode-select --install).
MLX42 (the graphics library) is included as a Git submodule and compiled automatically via CMake on the first build — no manual installation required.
git clone --recurse-submodules https://github.com/rodrigo-americo/42_miniRT.git
cd 42_miniRTIf you already cloned without --recurse-submodules:
git submodule update --init --recursivemake # mandatory version → ./miniRT
make bonus # bonus version → ./miniRT_bonus
make debug # debug build./miniRT scenes/complex.rt
./miniRT_bonus scenes/bonus_full.rt- Pass any
.rtscene file as the argument - Press
ESCor close the window to exit - The window supports resizing
Scene files are plain text. Each line defines one element.
A <intensity> <R,G,B> # Ambient light
C <x,y,z> <dx,dy,dz> <fov> # Camera
L <x,y,z> <brightness> <R,G,B> # Point light (multiple allowed)
sp <x,y,z> <diameter> <R,G,B>
pl <x,y,z> <nx,ny,nz> <R,G,B>
cy <x,y,z> <ax,ay,az> <diameter> <height> <R,G,B>
cn <x,y,z> <ax,ay,az> <diameter> <height> <R,G,B> # bonus only
# Phong only
sp ... <R,G,B> <ks> <kd> <ka> <shininess> <reflectivity>
# Phong + checkerboard
sp ... <R,G,B> <ks> <kd> <ka> <shininess> <reflectivity> <R2,G2,B2> <checker_scale>
# Phong + checkerboard + bump mapping
sp ... <R,G,B> <ks> <kd> <ka> <shininess> <reflectivity> <R2,G2,B2> <checker_scale> <bump_scale> <bump_path>
# Use "none" as bump_path for procedural (sine-based) bumpDefaults when omitted: KA=0.2 · KD=0.7 · KS=0.2 · SHININESS=30 · REFLECTIVITY=0
A 0.3 255,255,255
C 0,5,-20 0,-0.2,1 60
L -20,30,-10 0.8 255,255,255
sp 0,0,15 6.0 255,0,0
pl 0,-3,0 0,1,0 200,200,200
cy 0,-3,2 0,1,0 2.0 6.0 255,128,0
- Exactly 1 camera (
C) and 1 ambient light (A) per file - File must have a
.rtextension - Intensities and brightness:
[0.0, 1.0] - RGB colors:
[0, 255] - Orientation vectors: components in
[-1.0, 1.0] - FOV:
[0, 180] - Diameter and height: positive values
42_miniRT/
├── include/ Mandatory version headers
├── include_bonus/ Bonus version headers
├── src/ Mandatory source code (28 files)
│ ├── parser/ .rt file parsing & validation
│ ├── intersect/ Ray-object intersection (sphere, plane, cylinder)
│ ├── lighting/ Phong model + shadow rays
│ ├── vectors/ 3D vector math library
│ ├── draw/ Pixel-by-pixel render loop
│ └── color/ RGBA operations & conversion
├── src_bonus/ Bonus source code (43 files)
│ ├── intersect/ + cone, checkerboard, bump mapping
│ ├── lighting/ + recursive reflection
│ ├── multithread/ Thread workers & tile queue
│ └── scene/ Material params, defaults, bump loading
├── scenes/ Sample and test .rt files
├── libft/ Custom C library
└── MLX42/ Graphics library (submodule)
- Ray Tracing in One Weekend — Peter Shirley. The foundational reference for this project.
- Scratchapixel — In-depth articles on ray-sphere intersection, the Phong model, shadows, and more.
- Phong Reflection Model — Wikipedia — Overview of ambient, diffuse, and specular components.
- Bump Mapping — Wikipedia — Explanation of normal perturbation techniques.
- MLX42 — Cross-platform graphics library used for window management and pixel rendering.
- GLFW — Windowing and input library (MLX42 dependency).
AI assistance (ChatGPT / GitHub Copilot) was used during this project for the following tasks:
- Debugging geometric edge cases — helping identify off-by-one errors in ray-cylinder cap intersection and cone height clamping.
- Explaining math concepts — clarifying tangent/bitangent frame construction for bump mapping and the derivation of quadratic discriminants.
- Code review suggestions — reviewing parser error handling logic and suggesting cleaner validation patterns.
- No code was generated wholesale by AI. All implementations were written and understood by the authors; AI was used as an interactive reference, not a code generator.
| Contributor | Main contributions |
|---|---|
| rgregori (@rodrigo-americo) | Full parser, lighting, geometric calculations, bonus items (cone, MSAA, reflection, bump mapping, checkerboard, materials) |
| tlavared (@Talen400) | Geometric calculations, multi-threading with pthreads, overall structure |