What is Per-Tile Rasterization (Renderer)?

Rasterization: The process of determining which pixels a given primitive touches. Rasterization and pixel coloring are performed on a per-tile basis with the following steps:

  1. When a tile operation begins, the corresponding tile list is retrieved from the Parameter Buffer (PB) to identify the screen-space primitive data that needs to be fetched.
  2. The Image Synthesis Processor (ISP) fetches the primitive data and performs Hidden Surface Removal (HSR), along with depth and stencil tests. The ISP only fetches screen-space position data for the geometry within the tile.
  3. The Tag Buffer contains information about which triangle is on the top for each pixel.
  4. The Texture and Shading Processor (TSP) then applies coloring operations, like fragment shaders, to the visible pixels.
  5. Alpha testing and subsequently alpha blending is then carried out.
  6. Once the tile’s render is complete, the color data is written to the frame buffer in system memory.

This process is repeated until all tiles have been processed and the frame buffer is complete.