Ronald

Path tracing rendering engine in poorly written C++20

Building / Testing / Running

# Release build
make release
./build/ronald --help

# Debug build
make debug

# Build and run unit tests
make test

Basic Feature Set

• CLI parsing
• PPM image generation
• Vec3 class implementation
• Ray/Sphere intersection calculation
• Ray/Triangle intersection
• Diffuse material scatter function
• Light source material
• Dielectric material
• Recursive tracing function
• Realistic camera model with aperture and field of view
• Single threaded render loop
• Clamp to [0, 1] tone mapping
• Scene description using JSON/JSONC config file

Extended Feature Set (Not considered MVP or required for final submission)

• Axis-aligned bounding box class
• Bounding Volume Hierarchy [1]
• Multithreaded render loop
• Reinhard Tone Mapping
• Reflective/semi-reflective material, including shallow-angle reflection and total internal reflection
• Russian Roulette path termination

[1] BVH is implemented but currently has poor (but still correct) performance when used in a multi-threaded context. I have not had the time to profile the app and determine the cause of the performance degradation, and since the BVH was outside of the project MVP from the beginning I am going to leave it as-is.

Progress Updates

2022-06-21 -- Resolved Dielectric material artifact errors

There was a long-standing error with Dielectric materials caused by setting T_MIN too low in the hit_objects function. After hours of rummaging around in the code the bug was located and fixed. Now the program can render nice looking glass materials.

Config	Value
Resolution	512x512
Samples	10000
Threads	10
TMO	Reinhard Jodie
Render Time	18m57s
Commit	a9d5e33f

2022-06-15 -- Implemented Russian Roulette Path Termination

A description of Russian Roulette termination can be found in the /resources folder. I've also included comments in the relevant portion of code. The final image looks identical, but notice that the render time has gone down from 33 minutes to just 20 minutes. This is a huge savings for just a few extra lines of code.

Config	Value
Resolution	512x512
Samples	10000
Threads	10
TMO	Reinhard Jodie
Render Time	20m07s
Commit	153672b8

2022-06-15 -- Resolved vertical line artifacts

A longer description of the fix is included in the commit message. This commit marks the completion of the "MVP" portion of the project. I think at this point the project is probably in a "submittable" state and would receive a good grade.

Config	Value
Resolution	512x512
Samples	10000
Threads	10
TMO	Reinhard Jodie
Render Time	33m40s
Commit	5c31f121

2022-06-14 -- Added full Cornell Box Scene

Added the full Cornell Box scene geometry based on the specification from their website. There is still a persisting bug where the renderer produces "vertical line" artifacts (look closely at the green wall). The boxes themselves also aren't completely perpendicular to the floor so there is some weird shading on the front of the taller box

Config	Value
Resolution	512x512
Samples	10000
Threads	10
TMO	Reinhard Jodie
Render Time	51m36s
Commit	61cd6ee5

2022-06-14 -- Implemented multi-threaded rendering

Config	Value
Resolution	512x512
Samples	7000
Threads	10
TMO	Reinhard Jodie
Render Time	14m56s
Commit	b9d00140

2022-06-12 -- Successfully rendered the Cornell Box exterior

Config	Value
Resolution	512x512
Samples	7000
Threads	1
TMO	Reinhard Jodie
Render Time	5h6m57s
Commit	b6bbaab5