
3.1 Software Rendering 167
Display. The final pixel color is written to the render target, typically the frame
buffer, but often an offscreen chunk of memory.
As mentioned, the software renderer does not currently support all these features.
Moreover, the order of the operations is different from what Direct3D and OpenGL
support. The main reason for this is that the pixel shader is the bottleneck in a
software rendering system. Most graphics systems are fill-rate limited; it takes a lot of
time to process a large number of pixels. Rather than always calling the pixel program
at the beginning of the pipeline, the software renderer waits to see if the