Nak explains his navigation system's pathfinding

In #developer-talk, Nak explained his navigation system to Zemen. It runs a double A* search from start to goal and from goal to start, meeting in the middle ("a trick GPS use"). The search tracks polygon entry points, and the system reads the map's AIN info_nodes. NPCs such as the 200 antlions in his video run a "dumb" AI while waiting for a path, so they seem to react immediately.