Hitboxes

Hitboxes are defined in a static ship hitbox table at 0x0067AB30:

It creates the following shapes of ships facing north:

Projectile Collisions

The get_sea_battle_projectile_impact_direction function at 0x0060A73C determines whether and where a ship is hit by a projectile.

First it rotates the ship's hitbox coordinates (in its own coordinate space, i.e. around its origin). Since the ship's direction rotates clockwise and the Y-axis is inverted, the formula for counter-clockwise rotation can be used: \[x_{hitbox}' = x_{hitbox} * cos(a) - y_{hitbox} * sin(a)\] \[y_{hitbox}' = x_{hitbox} * sin(a) + y_{hitbox} * cos(a)\]

Then it adds the rotated hitbox coordinates to the ship coordinates, and transforms them into a projectile-centric space: \[x_{hitbox}'' = x_{ship} + x_{hitbox}'' - x_{projectile}\] \[y_{hitbox}'' = y_{ship} + y_{hitbox}'' - y_{projectile}\]

Finally it calculates the intersection (if any) of all ship hitbox lines and the line from the projectile's current position to its future position at the next tick, and decides whether the ship was hit on the port, starboard or a random side.

Impact Location

The get_sea_battle_projectile_impact_direction function returns the calculated impact location:

enum impact_location : __int8
{
    impact_location_none   = 0x0,
    impact_location_left   = 0x1,
    impact_location_right  = 0x2,
    impact_location_random = 0x3,
};

Should a projectile intersect hitbox lines with different associated impact locations, the result is set to random. The jump table at 0x0060AD69 maps intersections of the projectile's path with the ship's hitbox lines to impact locations:

This defines the following line-to-location mapping:

The mapping is incorrect, as discussed in the Known Bugs chapter.