Building a Tiny 3D Renderer for a Tiny Handheld

Summary

Today I want to talk about my journey writing a 3D software renderer for the Playdate. At the beginning, I didn't have any performance baseline. I had no idea how feasible my idea was, so I started with a simple test: a raycaster. I had written one many years ago, based on the code examples from Ken Silverman's webpage, and since then it has basically become what I write whenever I want to test the 3D processing power and screen drawing performance of a low-power device. You don't need much to write, compile, and run this kind of test, and it gives you a rough idea of the device's processing power. More specifically, it lets you benchmark the areas that matter most for a 3D renderer: how fast it handles floats and vector math, how fast it performs memory operations, how quickly it can draw to the screen, and whether there are any issues with setting up and using a framebuffer. The initial results were worse than I expected. The performance was bad enough that it became clear this was not going to be an easy project. To be clear, my raycaster was not written with top performance in mind. This was never about getting a raycasting engine working on Playdate. I'm pretty sure that, with enough optimizations, that can be done. The point was to get a feeling of how much of a powerhouse this device is (or isn't). This test helped me to get a better understanding of the capabilities of the handheld. It was clear that it didn't have enough power to draw 3D scenes at the level of early 3D accelerators, such as the 3dfx Voodoo, or compete with what you can do on the original PlayStation. But there was hope. The Playdate has a small, low resolution screen, and because it uses a 1-bit display, there are huge memory gains to be had. From the results I was still confident that I could make something that, from a player's perspective, felt close to the 3DO or Sega Saturn era. I should clarify what I mean by that. When I talk about something similar to a 3DO or Saturn game, I mean th...