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# COM S 327 Programming Project 1.02 Moving from map to map solution

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## Description

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In the first week we generated maps that had gates1
, theoretically to other maps. This week we’ll be
using those gates to connect to other terrain maps.
Later, we’ll use a library called curses to add a proper user interface. For now, we’ll simply print to
and read from the standard input at the terminal using standard I/O. We’re going to implement 6 commands,
all of which will have to be followed with the enter key because of buffered I/O (something curses will
eliminate for us).

## The commands are:

• n: Move to the map immediately north of the current map and display it.
• s: Move to the map immediately south of the current map and display it.
• e: Move to the map immediately east of the current map and display it.
• w: Move to the map immediately west of the current map and display it.
• f x y: x and y are integers; Fly2
to map (x, y) and display it.
• q: Quit the game.

Other input should be handled gracefully; don’t crash, and—ideally—print an error message.
Our world will measure 401 × 401 maps; we begin in the center, which we’ll call map (0,0) but may be
easier thought of internally as (200,200).

Movement commands that would cause display to move off the
edge of the world are ignored (i.e., redisplay the current map, optionally accompanied by an error message).
At all times, display the coordinates of the current map beneath the map itself.
Later, when we add Pokemon to the game, the levels of wild-spawned Pok ´ emon will be a function of ´
the distance from the center.

The frequency of Pokemarts and Pok ´ emon Centers should decline as we move out in order to increase ´
game difficulty. Your starting position (the center, map (0,0)) should always have both buildings. As we
move out, the probability of each building should be a function of the distance. This is a value that can
be tweaked for game balance later, but something like −45d/200+50
100 gives the chance of a building being
created for distance less than 200, and a flat 5% for distances 200+, where d is the Manhattan distance from
the center, is reasonable3

. This gives roughly a 50% probability of each building when close to the center,
falling off linearly to 5% near a center edge or farther.
When generating maps adjacent to previously-generated maps, gates should match up. For instance,
if you begin your game at (0,0) and move n n e e s s w n, you will be in (1,-1) (assuming n is the
negative y direction. All of (1,-1)’s neighbors will have been generated before (1,-1)

. The height position of
(1,-1)’s west gate should match that of (0,-1)’s east gate, (1,-1)’s north gate should align with (1,-2)’s south
gate, and so on for each direction. To implement this, you’ll want your map gates to be a parameter to your
map generator, which may require a small refactor of the 1.01 interface.

No map should ever be generated until it is visited. All visited maps should be saved such that they
can be visited again by going to the original coordinates (revisiting a coordinate should never generate new
terrain).
In addition to aligning neighboring gates, maps on the edges of the world should not have gates on their
world-bordering edges.
1

I’d previously been referring to these as “exits”. I never liked that name, but had failed to come up with anything better. A
student referred to them as gates and I liked it, so I’m calling them gates now.
2
It would be teleport or jump, but this is a Pokemon game ´
3
In case you’re wondering where this odd formulation came from, it’s just the slope-intercept form of a line through the points
(0, 50) and (200, 5).

The suggested approach is to have a 401 × 401 array of pointers to maps. Initially all maps in the
array are NULL, except for the center (internally (200,200); externally (0,0)). When generating a new map,
malloc the necessary storage and assign it to the appropriate pointer in the array.

Checking for the existence
of a map is a simple matter of testing a pointer for NULL.
All code in C!