Four synchronized implementations. Follow each input sample from CPU pointer events through GPU brush motion, individual texture cells, material simulation, and final pixels. Rotate every stack, step through a stroke, or inspect a single cell.
This is an interactive teaching model, not an execution trace, numerical replica, driver test or faithful reproduction of every shader. Its 16 × 16 cells are representative GPU texels, not screen-resolution pixels. The numerical values and timings are synthetic and normalized so you can see state transitions and architectural differences. The original algorithms and Chroma code establish the step ordering, GPU field roles and data flow. A real GPU trace would require in-app instrumentation, WebGL capture and reading live shader outputs.
David Li: brush.js and simulator.js. Chroma: GPU paint (oil and watercolor), V2 transactions, and GPU hair path.