Blog
Read the full intro
When studying animation and graphics, new algorithms usually reach us through textbooks or papers: condensed into equations, or illustrated with a few carefully chosen figures along the way.
How was it for you? For me, it was frustrating every single time. Because all I wanted was to run the algorithm as soon as possible and experience it directly.
What I didn't expect was how much work it would take to turn a newly encountered algorithm into a working program.
Sometimes it was a neatly compiled program written in an unfamiliar language. Other times it was a MATLAB prototype. In some cases, you had to prepare a very specific solver, or equip the whole thing with a nontrivial accelerator just to get it running.
From a beginner's perspective, many beautiful algorithms remained frozen as static images in books or PDFs, or preserved as decade-old Vimeo or YouTube videos, almost as if they were mocking you: "Oh, you want to try running me yourself?"
On rare occasions, getting your hands on a runnable demo or source code required either the author's stubborn determination, or an unusual level of generosity on their part.
This series is also my small attempt to close that gap.
In this series, I collect gem-like materials I encountered while studying graphics, and rebuild them into forms that can be executed anywhere, immediately.
Sections
0. Intro
Why this demo series exists
1. Explicit Euler
Basic force accumulation and forward step
2. Symplectic Euler
Velocity-first update for better stability
3. Symplectic Euler (matrix form)
System matrix view of the same update
4. Implicit Euler
More stable solve-based integration