🌟 miniRT - Ray Tracing Engine

📝 Introduction

miniRT is a 42 School project that implements a minimal ray tracing engine, introducing students to the fundamentals of 3D computer graphics, ray tracing algorithms, and mathematical concepts in rendering.

"Creating entire worlds with nothing but rays of light."

This project renders 3D scenes described in simple .rt files, calculating ray-object intersections and lighting to produce realistic images with depth, shadows, and perspective.

🎯 Project Objectives

• Implement a basic ray tracing engine from scratch
• Master 3D vector mathematics and geometric calculations
• Understand light behavior and shading models
• Parse and validate scene description files
• Render 3D primitives (spheres, planes, cylinders)
• Interface with the MiniLibX library for image display
• Optimize rendering algorithms for performance

🧩 Project Structure

miniRT/
├── inc/ # Header files
│ └── main.h # MiniLibX interface declarations
├── src/ # Source files
│ ├── main.c # Program entry point
│ ├── parser/ # Scene file parsing
│ ├── render/ # Ray tracing implementation
│ ├── utils/ # Utility functions
│ └── mlx/ # MiniLibX interface
├── scenes/ # Example scene files
└── Makefile # Compilation instructions

🛠️ Implementation Details

main.c

Program entry point:

Function	Description
main	Validates command-line arguments, initializes the scene, and starts the rendering loop

parser/

Scene file parsing:

Function	Description
parse_scene	Parses the .rt file and populates the scene data structure
parse_camera	Parses camera information from the tokens
parse_light	Parses light information from the tokens
parse_object	Parses object information (spheres, planes, cylinders) from the tokens

render/

Ray tracing implementation:

Function	Description
render_scene	Renders the entire scene by casting rays through each pixel
trace_ray	Traces a ray through the scene and computes the color seen along that ray
intersect_sphere	Checks for intersection between a ray and a sphere
intersect_plane	Checks for intersection between a ray and a plane
intersect_cylinder	Checks for intersection between a ray and a cylinder

utils/

Utility functions:

Function	Description
vec3_add	Adds two 3D vectors
vec3_sub	Subtracts vector b from vector a
vec3_scale	Scales a vector by a scalar
vec3_dot	Computes the dot product of two vectors
vec3_cross	Computes the cross product of two vectors
error_exit	Prints an error message and exits the program

mlx/

MiniLibX interface:

Function	Description
init_window	Initializes the window using MiniLibX
put_pixel	Draws a pixel at the specified coordinates with the given color
display_image	Displays the rendered image in the window

🧮 The Problem

Ray tracing solves the rendering equation by simulating how light interacts with objects:

• For each pixel, cast a ray from the camera through the pixel into the scene
• Determine which object (if any) the ray intersects first
• Calculate the color at the intersection point based on material properties and light sources
• Account for shadows by casting rays from the intersection point to each light source
• (Optional) Calculate reflections and refractions with recursive ray tracing

🎮 Program Usage

./miniRT <scene_file.rt>

Scene File Format

Scene files use the .rt extension and follow a specific format:

# Comment lines start with #
# Ambient lighting
A <intensity> <r,g,b>
# Camera
C <position> <orientation> <FOV>
# Light
L <position> <intensity> <r,g,b>
# Sphere
sp <position> <diameter> <r,g,b>
# Plane
pl <position> <normal> <r,g,b>
# Cylinder
cy <position> <orientation> <diameter> <height> <r,g,b>

Example:

A 0.2 255,255,255
C 0,0,0 0,0,1 70
L -40,0,30 0.7 255,255,255
sp 0,0,20 20 255,0,0
pl 0,-30,0 0,1,0 0,255,0
cy 50,0,20 0,1,0 14.2 21.42 10,0,255

💡 Key Features

• Ray-Object Intersection: Precise mathematical calculations for determining ray intersections
• Phong Shading Model: Realistic lighting with ambient, diffuse, and specular components
• Multiple Light Sources: Support for multiple point lights with shadow casting
• Scene Description Files: Flexible scene configuration through simple text files
• 3D Primitives: Support for basic geometric shapes (spheres, planes, cylinders)
• Camera Configuration: Adjustable camera position, orientation, and field of view
• MiniLibX Integration: Real-time rendering and display using the MiniLibX library

🧠 Skills Developed

• 3D vector mathematics and linear algebra
• Ray tracing algorithms and techniques
• Light physics and illumination models
• Geometric calculations for 3D primitives
• File parsing and validation
• Graphics programming with MiniLibX
• Optimization techniques for computational graphics

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📊 Project Stats

Metric	Value
Final Score	100/100
Primitives	Spheres, Planes, Cylinders
Lighting Model	Phong Shading
Performance	Optimized ray-object intersections