A Plainsight Systems project
A study in light
and computation.
I’m exploring GPU performance from the rendering side: how to process data in small pieces, carry less state, and reuse work. The same questions turn up in transformer inference, and the moving lights give me a way to see what the kernel work makes possible.
01 / The scene
C++20 · Metal 4 · Apple silicon
Thirty-six marbles on a walnut table at night. The light comes from 616 fireflies, waking one by one and moving among the glass, porcelain, and metal.
The naive path tracer gives me an image to judge and a frame whose cost I can measure. I’ll use that baseline to find out whether better sampling reduces the error enough to justify the work it adds.
Read what it took02 / Where we started
The first scene was a brass sphere on a checkerboard. Before the marbles and the swarms, there was light falling on one curved surface, a reflection, and a shadow.
I kept the geometry simple as the scene grew. The interesting part is what the light does, and what it costs to work that out.
Open the original image
03 / The question underneath
A renderer has more possible light paths than it can afford to trace. An inference engine has more intermediate data than it wants to move through memory. Both make you think carefully about what to keep, what to combine, and when to reuse earlier work.
Those are the connections I’m here to explore. ReSTIR’s reservoirs carry a small amount of running state; attention kernels also combine partial results without keeping every intermediate. The operations differ, but the questions about memory, scheduling, and GPU occupancy are familiar.
Serenity gives me a way to investigate them with something visible at the end. For now, the path tracer is built. ReSTIR is the next piece, in progress on a branch.
The scene, the reference image, and the measurements behind the first milestone. Along the way: plausible images hiding real bugs, production designs that made this scene slower, and why a frame time needs its method beside it.
Read the milestoneReSTIR: choosing and reusing light samples.