Credits

Credits & citations

The software and research Harlow is built on.

Harlow stands on a lot of other people's work: software it ships with, and research it implements. This page credits both. The plugin's own THIRD_PARTY_NOTICES.txt has the full license texts.

Third-party software#

In the plugin#

Component Used for License
NVIDIA OptiX 9.1 Ray tracing (headers; the runtime ships with the NVIDIA driver) NVIDIA SDK License
NVIDIA DLSS Ray Reconstruction Denoising and upscaling (nvngx_dlssd.dll) NVIDIA RTX SDKs License
NVIDIA CUDA Toolkit GPU solvers (runtime linked statically) CUDA Toolkit EULA
CUB / CCCL GPU sorting and scans Apache 2.0 with LLVM exceptions
Vulkan headers Sharing images with DLSS Apache 2.0 or MIT
avbd-demo3d by Chris Giles Reference for HRLW Bodies' contacts, joints and solve MIT
Monocypher 4.0.3 by Loup Vaillant and contributors Checking license keys CC0 1.0 or BSD 2-clause

On this website#

Component Used for License
Inter by Rasmus Andersson Text SIL Open Font License 1.1
JetBrains Mono by JetBrains Code and labels SIL Open Font License 1.1
marked Building the docs pages (build time only) MIT

Research#

Harlow implements methods from the papers below. Thank you to their authors for publishing them.

Rendering#

  • Bitterli, Wyman, Pharr, Shirley, Lefohn, Jarosz. Spatiotemporal Reservoir Resampling for Real-Time Ray Tracing with Dynamic Direct Lighting. ACM Transactions on Graphics (SIGGRAPH), 2020. ReSTIR direct lighting.
  • Lin, Kettunen, Bitterli, Pantaleoni, Yuksel, Wyman. Generalized Resampled Importance Sampling: Foundations of ReSTIR. ACM Transactions on Graphics (SIGGRAPH), 2022. ReSTIR path reuse.
  • Lin, Kettunen, Wyman. ReSTIR PT Enhanced: Algorithmic Advances for Faster and More Robust ReSTIR Path Tracing. Proceedings of the ACM on Computer Graphics and Interactive Techniques (I3D), 2026. Path reuse.
  • Junkins, Kettunen, Lin, Ramamoorthi, Wyman. Compatibility-Guided Neighbor Selection for ReSTIR. Proceedings of the ACM on Computer Graphics and Interactive Techniques, 2026. Spatial reuse.
  • Zeng, Liu, Yang, Wang, Yan. Temporally Reliable Motion Vectors for Real-time Ray Tracing. Computer Graphics Forum (Eurographics), 2021. History for newly visible surfaces.
  • Conty Estevez, Kulla. Importance Sampling of Many Lights with Adaptive Tree Splitting. Proceedings of the ACM on Computer Graphics and Interactive Techniques (HPG), 2018. Light tree.
  • Karras. Maximizing Parallelism in the Construction of BVHs, Octrees, and k-d Trees. High-Performance Graphics, 2012. Light tree construction.
  • Hanika, Droske, Fascione. Manifold Next Event Estimation. Computer Graphics Forum (EGSR), 2015. Caustics through water and glass.
  • Zhang, d'Eon. Real-Time Subsurface Scattering via Hybrid ReSTIR-Path-Tracing and Diffusion. SIGGRAPH 2025 Advances in Real-Time Rendering course. Subsurface scattering.

Materials#

  • Walter, Marschner, Li, Torrance. Microfacet Models for Refraction through Rough Surfaces. Eurographics Symposium on Rendering, 2007. Rough glass.
  • Heitz. Sampling the GGX Distribution of Visible Normals. Journal of Computer Graphics Techniques, 2018.
  • Turquin. Practical Multiple Scattering Compensation for Microfacet Models. Industrial Light & Magic technical report, 2019.
  • Kutz, Hasan, Edmondson. Novel Aspects of the Adobe Standard Material. Adobe technical report, 2021. Metal edge tint (F82).
  • Belcour, Barla. A Practical Extension to Microfacet Theory for the Modeling of Varying Iridescence. ACM Transactions on Graphics (SIGGRAPH), 2017. Thin-film iridescence.
  • Estevez, Kulla. Production Friendly Microfacet Sheen BRDF. Sony Pictures Imageworks technical report, 2017. Sheen.
  • Duff, Burgess, Christensen, Hery, Kensler, Liani, Villemin. Building an Orthonormal Basis, Revisited. Journal of Computer Graphics Techniques, 2017.
  • Wyman, Sloan, Shirley. Simple Analytic Approximations to the CIE XYZ Color Matching Functions. Journal of Computer Graphics Techniques, 2013. Dispersion and iridescence colours.
  • Lagarde. Water drop 2b: Dynamic rain and its effects. Blog post, 2013. Wet surfaces.
  • Worley. A Cellular Texture Basis Function. SIGGRAPH, 1996. Char cracks.
  • Narkowicz. ACES Filmic Tone Mapping Curve. Blog post, 2015.
  • Reinhard, Stark, Shirley, Ferwerda. Photographic Tone Reproduction for Digital Images. ACM Transactions on Graphics (SIGGRAPH), 2002.

Volumes#

  • Henyey, Greenstein. Diffuse Radiation in the Galaxy. Astrophysical Journal, 1941. Smoke scattering.
  • Novák, Selle, Jarosz. Residual Ratio Tracking for Estimating Attenuation in Participating Media. ACM Transactions on Graphics (SIGGRAPH Asia), 2014.
  • Kettunen, d'Eon, Pantaleoni, Novák. An Unbiased Ray-Marching Transmittance Estimator. ACM Transactions on Graphics (SIGGRAPH), 2021.
  • Sigg, Hadwiger. Fast Third-Order Texture Filtering. GPU Gems 2, 2005. Smooth volume lookups.

Fluids#

  • Zhu, Bridson. Animating Sand as a Fluid. ACM Transactions on Graphics (SIGGRAPH), 2005. The FLIP method.
  • Losasso, Gibou, Fedkiw. Simulating Water and Smoke with an Octree Data Structure. ACM Transactions on Graphics (SIGGRAPH), 2004.
  • Braun, Bender, Thuerey. Adaptive Phase-Field-FLIP for Very Large Scale Two-Phase Fluid Simulation. 2025. Adaptive particles and the two-level pressure grid.
  • Yu, Turk. Reconstructing Surfaces of Particle-Based Fluids Using Anisotropic Kernels. ACM Transactions on Graphics, 2013. The liquid surface.
  • Ihmsen, Akinci, Akinci, Teschner. Unified Spray, Foam and Bubbles for Particle-Based Fluids. The Visual Computer, 2012. Whitewater.
  • Selle, Fedkiw, Kim, Liu, Rossignac. An Unconditionally Stable MacCormack Method. Journal of Scientific Computing, 2008. Smoke and fire advection.
  • Zehnder, Narain, Thomaszewski. An Advection-Reflection Solver for Detail-Preserving Fluid Simulation. ACM Transactions on Graphics (SIGGRAPH), 2018.

Bodies#

  • Giles, Diaz, Yuksel. Augmented Vertex Block Descent. ACM Transactions on Graphics (SIGGRAPH), 2025. The HRLW Bodies solver.
  • Chen, Liu, Yang, Yuksel. Vertex Block Descent. ACM Transactions on Graphics (SIGGRAPH), 2024. Soft bodies.
  • Müller, Heidelberger, Teschner, Gross. Meshless Deformations Based on Shape Matching. ACM Transactions on Graphics (SIGGRAPH), 2005.
  • Müller, Bender, Chentanez, Macklin. A Robust Method to Extract the Rotational Part of Deformations. Motion in Games, 2016.

Citing Harlow#

If you use Harlow in research or publish work made with it, a credit or citation is appreciated:

Pyno Stevens. Harlow: real-time path tracing and GPU physics for TouchDesigner. 2026. https://harlow-engine.com

@software{harlow,
  author = {Pyno Stevens},
  title  = {Harlow: Real-Time Path Tracing and GPU Physics for TouchDesigner},
  year   = {2026},
  url    = {https://harlow-engine.com}
}

In a project's credits, "Rendered with Harlow" with a link to https://harlow-engine.com is perfect.