Planning/Plan/phaseI.md

Phase 1: C-Based GPU Emulator (3–4 Months)

Objective: Build a minimal GPU emulator in C, linked against PortableGL, to simulate a basic rendering pipeline with a command buffer-driven architecture.

Tasks:

• Proposed Architecture Design:
  • Define a gpu_state struct containing command buffer, rasterizer state, shader core state, and memory (VRAM, framebuffer).
  • Design a pure or in-place tick function to process commands and update gpu_state.
  • Specify a command buffer format (e.g., tagged union for draw, bind, state commands).
• PortableGL Integration:
  • Wrap or modify PortableGL to enqueue OpenGL commands (e.g., glDrawArrays, glBindTexture) into the GPU’s command buffer.
  • Bypass PortableGL’s rendering pipeline to use the custom GPU model for processing.
• Core Components:
  • Implement a command processor to dequeue and dispatch commands.
  • Develop a simple vertex and fragment shader executor (C functions).
  • Create a rasterizer for triangle scan conversion and fragment generation.
  • Simulate GPU memory as a byte array for vertex buffers, textures, and framebuffer.
• Testing:
  • Test with PortableGL’s “hello triangle” example to render a single triangle.
  • Output the framebuffer to a file (e.g., PPM image) for verification.
• Documentation:
  • Document the C model’s architecture, command buffer format, and PortableGL integration.
  • Provide setup instructions for building and running the emulator.