Before a ship starts moving, its waypoint needs be known (in form of a X/Y pair, or, actually, a dX/dY displacement). Intercept resolution attempts to ensure that for intercepting ships.

If a wraparound universe is being used, ships move the shortest possible path to reach their waypoint (i.e. "100 ly to the east", not "1900 ly to the west"). After moving across a map seam, they are moved into the map again: if a ship moves 50 ly east of the right seam (outside the map), it will end up 50 ly east of the left seam (inside the map).

Speed Limit: Damage may force a ship to slow down. Note that the maximum speed is Warp 9, even if the formula yields a higher value.

Max_speed =
   9                 ...if ship has Hardened Engines
   15 - Trunc(Damage/10)
                     ...if ship owner is Lizards
   10 - Trunc(Damage/10)
                     ...otherwise

Basics: First, we compute the maximum distance permitted by our warp factor. This is the permitted movement distance for our ship. Both values may change during movement.

Max_dist =
   Warp^2            ...for normal engines
   Warp^2 * 2        ...for gravitonic engines

Permitted_dist =
   Max_dist          ...if ship has fuel
   1                 ...if ship has no fuel, and AllowNoFuelMovement is on
   0                 ...if ship has no fuel, and AllowNoFuelMovement is off

PHost uses a time-based reasoning to move ships. Normally, a ship has one time unit to move. It doesn't need to use that unit completely. A ship moving towards a 32 ly waypoint at Warp 8 will usually reach that waypoint after one-half time unit. Mine hits can cause the ship to stop or change speed after a particular time. If a towed ship breaks free after its tower hit a mine, for example, it can use the remaining time not used by its tower to reach its own waypoint.

The distance a ship is allowed to move is computed using the identity

Movement_distance =
   Max_dist * Movement_time
This is a testing version.
It may be incomplete, and have more bugs (or features) than the public live version at planetscentral.com.