A tiny, one-file, Monte Carlo path tracer written in a few hundred lines of Ruby. The source accompanied a short talk I gave as an introduction to Ray Tracing (presentation slides available here). The hope is that it provides a simple to understand example. The image below is the rendered output at 1024spp.

• Monte Carlo method
• Global illumination
• Diffuse, and specular BRDFs
• Ray-sphere intersection
• Soft shadows
• Anti-aliasing
• Modified Cornell box
• PNG image format output
• Progressive saving

$ ruby tiny-path.rb --help

Usage: tiny-path.rb [options]
    -w, --width=width                Image width
    -h, --height=height              Image height
    -s, --spp=spp                    Samples per pixel
    -o, --output=filename            Output filename
    -p, --[no-]progressive-save      Save file while rendering

To render the scene at 16 samples per pixel, run the following command,

$ ruby tiny-path.rb -s 16

It will save a file in the same directory titled output.png.

Julian Villella

Tiny Path is available under the MIT license. See the LICENSE file for more info.