Globaly Illuminated Dragon

Overview

This path tracer is a project used to experiment with the math used by commercial path tracers. I wanted this project to be easy to understand, so it is written in plain Java with minimal imports.

Features

Multithreading: The renderer can use any number of CPU cores to dramatically decrease the render time.

Bounding Volume Hierarchies: Upon loading a 3D object into the engine, it will algorithmically subdivide it’s mesh so the object can be rendered efficiently.

Global Illumination: Global illumination makes each object to act as a light source and allows for incredibly realistic lighting.

Real-time Display: You can watch your image render as the engine works on it in addition to the .png output.

Run it yourself

This project is light-weight so running it yourself is easy. The entire thing is compiled and run through a small batch script. Using batch does limit users to Windows, but that’s the price we pay for ease of use.

Install JDK on Windows
Clone this repository
Edit the run.bat file to change the render and directory settings

The render setting are specified by the args variable. For example, if I would like to render the image in 1080p with a real-time display I would have the following:

:: run.bat
SET args=1920 1080 -v

The first two numbers specify the resolution, and -v tells the path-tracer to create the realtime display.

The full list of rendering setting are as follows:

flag	desc
-m int	Enable multithreading and set pixel dimensions of the chunks
-a int	Set the sub-pixel sampling (antialiasing) resolution. For example, Supplying an argument of `2` will sample the pixel `2*2=4` times in a grid-like fashion.
-o	Enable `.png` file output on completion
-d	Enable realtime image display
-v	Verbose console output

Make sure to also create the directories in run.bat.

:: run.bat
:: Set the location for the *.class files
SET bin=bin
:: The dir containing the *.java files
SET src=src

The last step is providing your own .obj files and configuring src/PathTracer.java to load them.

No .objs on hand? No problem. Here are the standard free ones:

You can easily configure src/PathTracer.java to load your object files by doing something like this:

//src/PathTracer.java
public static void main(String[] args) {
    /* parser code ... */
    scene.meshes.add(OBJReader.read("obj/teapot.obj"));
    scene.meshes.add(OBJReader.read("obj/bunny.obj"));
    /* rendering code ... */
}