miniRT

A basic raytracer for 42 school project miniRT made by 0xAttra and Samael1254

*️⃣ Features

Create scenes containing varied shapes, meshes and lights, and render them through the technique of ray-tracing.

Each scene is configured in .rt files. See documentation.rt for more information.

This project comes with a few pre-made scenes, meshes, textures and materials to select from.

Shapes

• Four primitive shapes available: plane, sphere, cylinder, cone.
• The shapes are fully configurable : size, position, orientation, etc...
• They can be seen from the outside as well as inside.
• Light that does not hit any object goes into the sky, which can be configured as a horizontal gradiant of two colors.

Materials and textures

• Materials can be created in dedicated .mrt files (see documentation.mrt for more details).
• They contain all the visual parameters of the objects :
  • Colors : diffuse, ambiant and specular
  • Texture (in .xpm file format)
  • Normal map (in .xpm file format)
  • Physical properties : specularity, reflectivity, transparency and refractive index

Texture colors are blended with the material color

A space scene with a normal map for the moon and texture and normal map for the earth

Light

RGB lights add on the ground to give white, and subtract through the glass ball to give black

• Multiple point lights of any RGB color can be added to the scene.
• They can be visualized or hidden, by using the L key (see keybindings below).
• Point lights cast hard shadows, and are attenuated by the incidence angle and the distance travelled by the rays.
• An ambiant light of configurable brightness and color is present in every scene, to approximate global illumination in unlit areas.

Mesh rendering

• Load and render meshes in the .obj format (standalone loader also available here).

• Meshes can be scaled, moved and rotated in the scene configuration file.

• They are rendered using a Bounding Volume Hierarchy (BVH) to boost performance.

• They can also be lit with smooth shading, making low poly meshes look like smooth surfaces.

• ⚠️ Please note that only triangulated meshes can be loaded by miniRT so far.

Textures, normal maps and other material properties can be applied to meshes like any other object

Transparency

• Transparent materials allow light to pass through.
• Light is refracted through transparent materials according to their refraction index, while some of the light is also reflected as described by Fresnel equations.
• A material only partially transparent will give its color/texture to the light passing through it.

A refracting sphere acting as a distorting lense

A skull mesh made of red crystal

Reflection

Rays bounce around several times between the mirrors, creating seemingly infinite reflections

• Reflective materials act as perfect mirrors, but the reflection can be blended with the object color/texture to approximate a partially reflective material.

The specular (reflective) color can also be changed to give a material a metallic look

Post-processing

• Apply post-processing filters to your scene using the P key (see keybindings below), and give a stylish look to your scenes.

Negative, sepia and poster filters

User Interaction

• The user can move and rotate the camera around in real time to get different views of the scene (see keybindings below).
• Modifiable camera parameters (field of view, movement and rotation speed).
• A FPS counter can be displayed, as well as help for the different keybindings (also listed below).
• You can save the image currently displayed on the screen by pressing Space. The image will be saved as a .bmp file in the screenshots directory.

Configuration

• Please refer to the documentation.rt and documentation.mrt files to see how to configure scenes.

📦 Installation and usage

Clone and build miniRT at the location of your choice :

git clone --recurse-submodules https://github.com/Samael1254/miniRT.git
cd miniRT
make

⚠️ This project uses submodules for libraries. If you forgot to clone them recursively, execute this command in the repository:

git submodule update --init --recursive

Launch the program with the scene you want to render as a parameter :

./miniRT <scene>.rt

⌨️ Keybindings

The following keybindings allow the user to interact with miniRT:

• Zoom : Mouse scroll
• Move : WASD
• Rotate : Alt + WASD
• Change movement speed : Up/Down arrows
• Change rotation speed : Left/Right arrows
• Toggle FPS counter : F
• Toggle lights visibility : L
• Toggle anti-aliasing : K
• Next post-process filter : P
• Previous post-process filter : Shift-P
• Take screenshot: Space
• Help : H
• Exit : Escape

⏩ Future improvements

Parsing

• Set the texture scaling in the .mrt file
• Choose screen size (in .rt file or in command line)

User interaction

• Display filter name in the terminal when pressing P
• Display initialization time and total render time
• Lower movements steps
• CLI for interacting with the scene

Camera movement

• Drag and drop for rotations
• Change field of view in real time

Optimisation

⭕ Known issues

• uv mapping inside an object is upside down
• lights appear through plane-like surfaces
• deformation up and down the screen (fisheye)
• Strong ambiant lighting with weak point lights creates weird shadows
• Light halos and shadow rays are not refracted through transparent materials
• Movements are discontinuous when post processing is activated

🫂 Acknowledgements

Made in the context of a project in 42 school.

Graphics library: minilibx

Personnal functions library: new_libft

OBj file loader: obj_parser