Raytrace In A Weekend

In Kotlin

This is a pretty direct translation of https://github.com/petershirley/raytracinginoneweekend into kotlin.

Any bugs are my own.

Please feel free to copy / change / fork / raise issues as you see fit.

Intel Open Image Denoise

The program incorporates the Open Image Denoise library, so the "denoised" versions are real output from this renderer.

Example

Cornell Box

Renders in 1.8 seconds, 20spp

Denoised

Raw renderer output

Weekend Final Image

The below example is rendered with 2 samples/pixel, then loaded into Intel Open Image Denoise, and renders in 0.3 seconds.

Here is the rendered output, before denoise

Week Final Image

The Final, with 20 samples per pixel, renders in 12s, and gives the following output:

Denoised

Raw render output

Notes about the code

• Uses Intel Open Image Denoise (oidn) Library to improve quality of scenes (via https://github.com/time4tea/oidnjni)
• Uses Kotlin Co-routines for rendering in parallel, seems fairly effective
• Uses Kotlin-Scripting for allowing dynamically-reloading scenes that can be edited while the code is running
• Has an interactive mode: use Cursor-Keys, +/- to move camera, and 1/2 to dec/inc number of samples, s to save image

Changes from "Raytrace In a Weekend"

• Some stylistic changes for Kotlin (e.g. Hitable -> Hit? )
• Most things immutable, e.g. colours are the sum of the samples, not modified in place
• Uses x,y,z rather than an array for Vec3
• Added Triangle Primitive
• Added .obj file loading (poorly)
• Used BVH for Box

Main Programs

• Raytrace.kt - render a scene
• ControllableRaytrace.kt - render a scene and move around it
• DynamicRaytrace.kt - render a scene, which can be modified while program is running