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Strange random dungeon generation wrapping

jim hurley (36)
I wrote a very simple dungeon generator today. I am having a strange issue where if a room goes too high or low, it wraps to the bottom or top. I have no idea at all why this would happen, as I error check to make sure its not too high/low, and the result is out of the bounds of the array. Also, to make things even weirder, it only happens vertically. Any thoughts?

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using namespace std;

#include <iostream>
#include <ctime>
#include <fstream>

//Constants
const int cwidth = 140;
const int cheight = 70;

//Enumerations
enum DIRECTION {
	D_NULL = -1,
	LEFT = 0,	
	UP,
	RIGHT,
	DOWN
};

//Map Array
int map[cwidth][cheight];

//The file
fstream map_file;

//Functions
int random (int i);
void fill (int x, int y, int w, int h, int i);
void show (void);
bool collision (int x, int y, int w, int h);

void randomize_map (int room_size_min, int room_size_max, int room_count, int hallway_max);

int main(int argc, char **argv)
{
    srand((unsigned)time(0));

	start:

	randomize_map(2, 20, 40, 5);

	show();

	int test;

	cin >> test;

	goto start;
}

int random (int n)
{
	if (n == 0)
		return 0;

	return (rand() % n) + 1;
}

void fill (int x, int y, int w, int h, int i)
{
	for (int dy = y; dy < h + y; dy++)
	{
		for (int dx = x; dx < w + x; dx++)
		{
			map[dx][dy] = i;
		}
	}
}

void show (void)
{
	for (int y = 0; y < cheight; y++)
	{
		for (int x = 0; x < cwidth; x++)
		{
			cout << map[x][y];
		}
		cout << '\n';
	}
}

bool collision (int x, int y, int w, int h)
{
	for (int dy = y - 1; dy <= h + y + 1; dy++)
	{
		for (int dx = x - 1; dx <= w + x + 1; dx++)
		{
			if (map[dx][dy] != 0)
				return true;
		}
	}
	return false;
}

void randomize_map (int room_size_min, int room_size_max, int room_count, int hallway_max)
{
	////Create the basic map
	fill(0, 0, cwidth, cheight, 0);

	//Create the first room
	fill(((cwidth / 2) - (room_size_max / 2)), ((cheight / 2) - (room_size_max / 2)), room_size_max, room_size_max, 1);

	unsigned int q = 0;

	for (int i = 1; i < room_count; i)
	{
		DIRECTION direction;
		bool loop = true;

		direction = D_NULL;

		int rw = room_size_min + random(room_size_max - room_size_min);
		if (rw < 2) rw = 2;
		int rh = room_size_min + random(room_size_max - room_size_min);
		if (rh < 2) rh = 2;

		int rx = random(cwidth);
		int ry = random(cheight);

		int offset_x = random(rw - 1);
		int offset_y = random(rh - 1);
		int hallway = random(hallway_max);

		if (map[rx][ry] == 1)
		{

			if (map[rx - 1][ry] == 0)
				direction = LEFT;
			else if (map[rx][ry - 1] == 0)
				direction = UP;
			else if (map[rx + 1][ry] == 0)
				direction = RIGHT;
			else if (map[rx][ry + 1] == 0)
				direction = DOWN;

I think this is where the problem occurs: 
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			switch (direction)
			{
			case LEFT:
				if (rx - hallway - rw <= 0 || ry - offset_y <= 0)
					break;

				if (collision(rx - hallway - rw, ry - offset_y, rw, rh))
					break;

				fill(rx - hallway - rw, ry - offset_y, rw, rh, 1);

				fill(rx - hallway, ry, hallway, 1, 1);

				i++;
				break;

			case UP:
				if (rx - offset_x <= 0 || ry - hallway - rh <= 0)
					break;

				if (collision(rx - offset_x, ry - hallway - rh, rw, rh))
					break;
				
				fill(rx - offset_x, ry - hallway - rh, rw, rh, 1);

				fill(rx, ry - hallway, 1, hallway, 1);

				i++;
				break;

			case RIGHT:
				if (rx + hallway + rw >= cwidth || ry + offset_y >= cheight)
					break;
					
				if (collision(rx + hallway, ry - offset_y, rw, rh))
					break;

				fill(rx + hallway, ry - offset_y, rw, rh, 1);

				fill(rx, ry, hallway, 1, 1);

				i++;
				break;

			case DOWN:
				if (rx + offset_x >= cwidth || ry + hallway + rh >= cheight)
					break;

				if (collision(rx - offset_x, ry + hallway, rw, rh))
					break;
				
				fill(rx - offset_x, ry + hallway, rw, rh, 1);

				fill(rx, ry, 1, hallway, 1);

				i++;
				break;
			}
		}
		q++;
		if (q > 1000000000)
			i = room_count;
	}
}
Last edited on
Peter87 (11178)
Are you sure your output window is at least 140 characters wide?
jim hurley (36)
Yes, my problem is that the array is having a block of 1's filled from the bottom to the top, having a wrap effect. I am guessing it has something to do with the compiler handling out of bounds errors with my map array.
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