Show HN: Forge-GPU – 55 C lessons for SDL's GPU API, built with Claude Code

Open-source tutorial series teaching real-time graphics programming with SDL's GPU API. Covers everything from Hello Window to SSAO, with math lessons, engine lessons, and a UI track building font rendering from scratch. Every lesson is a standalone C program with commented code explaining why, not just what. The whole project was built with Claude Code. Each lesson also distills into a reusable Claude Code skill — copy them into your own project and build games with AI that actually understands the GPU patterns.