Raph Levien@armansito and I have been working for many months on a paper, GPU-Friendly Stroke Expansion. We're pleased to say it's been accepted to HPG 2024, and we'll present it July 26 in Denver.
A revised draft is at https://arxiv.org/abs/2405.00127. There's a lot of stuff in there, both math for the geometry of curves and GPU implementation techniques. We'll have some more material as we get closer to the conference and put together the talk.
GPU-friendly Stroke Expansion
Vector graphics includes both filled and stroked paths as the main primitives. While there are many techniques for rendering filled paths on GPU, stroked paths have proved more elusive. This paper presents a technique for performing stroke expansion, namely the generation of the outline representing the stroke of the given input path. Stroke expansion is a global problem, with challenging constraints on continuity and correctness. Nonetheless, we implement it using a fully parallel algorithm suitable for execution in a GPU compute shader, with minimal preprocessing. The output of our method can be either line or circular arc segments, both of which are well suited to GPU rendering, and the number of segments is minimal. We introduce several novel techniques, including an encoding of vector graphics primitives suitable for parallel processing, and an Euler spiral based method for computing approximations to parallel curves and evolutes.
Inês Almeida