Atari Quake 2: the BSP tree algorithm in 250 bytes of 68k

Quake II on 16MHz Atari Falcon030. See development blog playlist for progress:    • Atari Quake 2: very early test with f...  

Same as before, but this time the C code for Quake II's BSP tree traversal has been squeezed into 250 bytes (120 instructions) so it can execute rapidly from the Falcon's small 256-byte CPU cache.

The algorithm includes the original frustum clipping processes including the tracking of trivial accept/reject state propagated to subtree nodes.

This was done partly by hand optimization but also by removing all work from the BSP walk which could be processed externally in queues.

The outer and middle layers of the 3D engine is still too slow for purpose but it is converging towards a usable state, so the inner parts can be attempted.