Raycasting of a CSG Tree

Introduction

A CSG (Constructive Solid Geometry) tree is, in simple terms, a way of adding, subtracting, and intersecting shapes.
This project implements it using multithreading and CUDA for faster simulations by leveraging GPU threads for calculations.

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Content

• How It Works
• Build
• Instructions
• Input File
• Examples

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How It Works

This project uses raycasting with CUDA.
Each pixel is represented as a thread in CUDA.

How a pixel’s color is calculated:

1. Take a line from the camera position to the pixel.
2. Intersect this line with every shape in the scene.
3. Combine those intersections according to the structure of the CSG tree.

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Build

To build the project:

git clone https://github.com/pietraldo/raycasting_of_a_csg_tree --recursive --shallow-submodules
cmake -S . -B ./build

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Instructions

Moving in the Scene

• W – move forward
• S – move backward
• Right mouse button – control camera orientation

You can also control lighting and camera with:

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Input File

Example input files are in the example_models folder.

Objects

• Spheres: (x, y, z, radius, r, g, b)
  Example:

  s1) -6.8 1.12 -8 1 255 255 0
  

• Cubes: (x, y, z, a, b, h, r, g, b)
  Example:

  c1) 0 1 -9.5 1 1 1 0 255 255
  

• Cylinders: (x, y, z, radius, height, axis, r, g, b)
  Example:

  w1) -5 0 0 4 10 1 0 0 255 100 100
  

Operations

You can combine shapes to build a CSG tree:

t1) s1 - c1
t2) s1 + w1
t3) t2 * t1

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Examples