Image Credit: photo by John Fujii © 2025 ACM SIGGRAPH
Since 2023, ACM SIGGRAPH announces the Test-of-Time award-winning Technical Papers that have had a significant and lasting impact on computer graphics and interactive techniques over the last decade. We caught up with Miles Macklin, one of the authors of “Unified Particle Physics for Real-Time Applications” (2014), to learn more about this 2025 Test-of-Time award-winning paper and how it has impacted the computer graphics community over time.
SIGGRAPH: Congratulations on your Technical Papers Test-of-Time award. Can you explain the core idea behind your research and what problems you were trying to solve at the time?
Miles Macklin (MM): In the early-mid 2010s, graphics processing units (GPUs) were just starting to be used for real-time physics simulation. At the time, NVIDIA was heavily focused on gaming applications, and we were interested to see how far we could push real-time physics simulation on the GPU to add special effects to AAA games.
One of the challenges at the time was that GPU architectures were much more limited than they are today. They weren’t great at handling things like thread divergence and the complex geometry processing operations required for collision detection between meshes.
However, they were good at handling flat, small pieces of data, and this led us to try and define a physics engine that operated on a unified shape representation based entirely on particles. The novel contribution of our method was to show that it’s possible to simulate many types of multi-physics, such as fluids, cloth, smoke, and rigid bodies, using a single particle-based representation. This was well suited to the GPU and made it practical to do real-time simulation of many types of interesting physics where different materials could interact.
SIGGRAPH: Having won the Test-of-Time award, why do you think your work withstood the test of time? Were there aspects of the work that you thought were risky or ahead of time?
MM: The work in our paper was quite practical; it doesn’t require very sophisticated mathematics or even physics knowledge. It’s relatively easy to implement and gives researchers and developers a framework to build on that has proved quite successful in commercial applications, particularly in the visual effects industry. I believe the ease of implementation has helped the work to have a long-lasting impact.
The project was ambitious in the sense that we tried to push our unified representation to as many different types of dynamics as possible and tried to push GPU multi-physics in ways that hadn’t been tried before, especially for real-time applications.
SIGGRAPH: “Unified Particle Physics for Real-Time Applications” focuses on performance-critical systems. What have you learned about writing modular, performant, and future-proof software that could benefit each other?
MM: Good API design and software engineering are critically important for the adoption of any technology. Our paper was productized as NVIDIA Flex, a CUDA library that could be integrated into any user application. Designing the API to be efficient, easy to use, and unopinionated about its environment is very important for deployment. I recommend developers take inspiration from some of the great APIs of our time: CUDA, OpenGL, SQLite. These libraries show how to write solid APIs that will stand the test of time.
SIGGRAPH: If you had access to today’s hardware, data, or community resources when you wrote the paper, what would you have done differently or explored further?
MM: I think our method is still attractive in its simplicity; however, the restrictions of previous GPU generations are no longer present, and today I believe we could handle more complex shape representations directly. We now also have numerical optimization methods that reduce some of the approximations we made in the original paper, e.g., Projective Dynamics, Vertex Block Descent, and others have strong guarantees on the solutions they find and are quite practical today (and published at SIGGRAPH!).
SIGGRAPH: This paper has become foundational in computer graphics research. What advice would you give to today’s researchers who hope to make similarly lasting contributions?
MM: Our papers show that practical methods, with an emphasis on engineering, can have a big impact. I would encourage researchers to not treat engineering as an afterthought but something that can help elevate their work and its impact.
Congratulations to Miles and all of the SIGGRAPH 2025 Test-of-Time award winners! We can’t wait to see what awaits SIGGRAPH 2026 as we return to Los Angeles. Submissions open in late 2025.
Miles Macklin is a Senior Director of Simulation Technology at NVIDIA. He received his Ph.D. in Computer Science from the University of Copenhagen for his work on computer graphics, physics-based animation, and robotics. He has published several papers in the proceedings of ACM SIGGRAPH and his research has been integrated into many commercial products including NVIDIA’s Warp and Isaac platforms. His recent work aims to develop robust and efficient frameworks for differentiable programming on GPUs.
