Lumen
Lumen is a Vulkan ray tracing framework that contains a variety of variance reduction techniques. Its aim is to accelerate some of the well-known rendering techniques in computer graphics literature with the help of the ray tracing hardware in modern GPUs. All the techniques Lumen implements run fully on the GPU.
Features
Rendering Techniques
- Unidirectional Path Tracer with Multiple Importance Sampling (Path)
- Bidirectional Path Tracer (BDPT)
- Stochastic Progressive Photon Mapping (SPPM)
- Vertex Connection and Merging (VCM)
- Primary Sample Space Metropolis Light Transport (PSSMLT)
- Combined VCM + MLT Integrator (VCMMLT)
- ReSTIR
- ReSTIR GI
- ReSTIR PT / GRIS
- DDGI (Real time)
- FFT Convolution Bloom
Engine
- Diffuse, mirror, glass, conductor, dielectric and Disney Principled BSDF
- Spot (point), polygonal and directional lights
- JSON-based scene system
- Modified Mitsuba parser
- A lightweight Vulkan abstraction layer from scratch
- EXR output (F10)
- On-the-fly RMSE computation
- SPIRV reflection
-
Render graph support with experimental Vulkan features
- Automatic resource and synchronization management
- Binding inference based on shader reflection results
- Simple builder pattern
About experimental features
With the recently integrated render graph, Lumen uses some of the more experimental Vulkan features. These are namely,
- Templated push descriptors (may be problematic with AMD)
- Event-based syncronization (via syncronization2 API, available from Vulkan 1.3)
- Experimental feature, may not work depending on your driver (May need Vulkan beta drivers on Nvidia)
- Enabled via
use_events
flag in the Render Graph settings. (See RenderGraphSettings
in RenderGraphTypes.h
and RayTracer.cpp
)
Showcase
Caustics Glass (VCM)
Caustics Zoomed (VCM)
Mitsuba Torus (VCM)
Unbiased ReSTIR PT (aka GRIS) 1 sample per pixel (Indirect lighting only, on/off comparison)
Dynamic Diffuse Global Illumination (DDGI)
Building
To build Lumen, start cloning the repository with
git clone --recursive https://github.com/yuphin/Lumen.git
Requirements
- Vulkan SDK
- Turing+ or RDNA2 GPU
- CMake 3.4 or above (Credits to @Lachei for porting the project to CMake and testing it on Linux)
Usage
Some of the sample scenes can be found in the scenes/
directory.
Sample scene files with various integrators can be found in the scenes/cornell_box/
directory.
To load a scene file simply run:
Lumen.exe <scene_file>
Getting started with Lumen
The best way to get started is to take a look at the unidirectional path tracer implemented in src/Raytracer/Path.cpp and gradually explore the other integrators. From there, you can focus on the related shaders that are located in the src/shaders
folder.
References