将位置映射到数组索引

Question

Backstory: I'm making a simple maze game, where the maze is procedurally generated. I represent the maze as a 2D array of rooms, with 4 booleans storing whether or not each corner of a room has a wall. (if Room.south_wall == false, than the room is connected to the room to its south.) Each room and can have an arbitrary length and width. For simplicity's sake, I set it so that the length and width is determined at the beginning of generation and applied to all rooms. The position of the player is stored using 2 floats, one is their x coordinates, one is their y coordinates. The maze looks something like this (Thick black lines are the visible walls, thin red lines represent the 2d array):

As you can see, each room has a length and width of 3. What I want to be able to do is determine what room the player is in, given their position. So for example, in this instance:

The player is in room (1,0) (I've marked the origin and the center of room (1,0) to help see this)

I know this should be a simple question, but I've been unable to come up with anything for a few days now. Any suggestions would be greatly appreciated. Let me know if this isn't enough information.

Answer 1

If you have the player position px , py and your rooms are aligned so that room(0,0) is centred at (0.0, 0.0) then the index of the room would be

#include<cmath>
ix = int(std::round(px / room_width));
iy = int(std::round(py / room_height));

Also, as a general rule it's best to make room_width and room_height a constant rather than use a 'bare' (aka magic) number just in case you want to change it later.