Problem with random map generation

Hi programmer community!
I've got a problem. My program is supposed to generate a random map with roads and houses. The problem is in the house generation section. It keeps placing houses where it doesn't have to. Houses may only be placed next to a road. Can someone help me out?

Here is my code. I haven't included the whole program as that's all working fine.
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#include "Map.h"
#define max std::max
#define min std::min
/*Constructor*/
Map::Map(int width, int height) : 
	m_width(width),
	m_height(height),
	m_map(new std::vector< std::vector<Building*> >)	
{
	/*Resize the 2D std::vector to the specified width and height*/
	m_map->resize(m_height); //We need m_height sub-vectors
	for (int i = 0; i < m_height; ++i)
		(*m_map)[i].resize(m_width); //each sub-vector has a size of m_width
	
	MIN_NUMBER_OF_BUILDINGS = m_width * m_height / 2 + max(m_width, m_height);
	
	/*Map generation algorithm
	 *The algorithm works as follows:
	 *1.Initialize whole map with empty buildings (=Grass)
	 *2.Create all roads
	 *3.Create buildings next to roads
	 *
	 *Road creation:
	 *	1.Take two random coordinates that are on one straight line
	 *	2.Connect those using a road
	 *	3.Somewhere on that road, take a new starting coordinate
	 *	4.Take a new point
	 *	5.Repeat this from step 2 until minimum possible buildings is reached
	 *	6.Min buildings = (width*height) / 2 - max(width, heigth)
	 */
	 
	 /*Initialization*/
	 #ifndef NDEBUG
	 std::cout << "Init map\n";
	 #endif
	 for (int i = 0; i < m_width; ++i)
	 	for (int j = 0; j < m_height; ++j)
	 		((*m_map)[i][j]) = new Grass(j,i);

		
	do
	{
		static bool firstIteration = true;
		int ROAD_X_COORD_1, ROAD_Y_COORD_1, ROAD_X_COORD_2, ROAD_Y_COORD_2;
		static int PREV_X,PREV_Y;
		/*The first iteration is different from the others, as our starting point is not based on the previous road*/
		if (firstIteration)
		{
			firstIteration = false;
			/*Step 1*/
			ROAD_X_COORD_1 = getRandomNumber(0,m_width - 1);
			ROAD_Y_COORD_1 = getRandomNumber(0,m_height - 1);
		}
		else
		{
			ROAD_X_COORD_1 = PREV_X;
			ROAD_Y_COORD_1 = PREV_Y;
		}
		/*Generate a random number to see if the road goes horizontal or vertical*/
		if (getRandomNumber(0,1) == 0) /*Horizontal*/
		{
			ROAD_Y_COORD_2 = ROAD_Y_COORD_1;
			ROAD_X_COORD_2 = getRandomNumber(0,m_width - 1);
			for (int i = min(ROAD_X_COORD_1, ROAD_X_COORD_2); i <= max(ROAD_X_COORD_1, ROAD_X_COORD_2); ++i)
			{
				(*m_map)[ROAD_Y_COORD_1][i]= new Road(i, ROAD_Y_COORD_1);
			}
			PREV_Y = ROAD_Y_COORD_1;
			PREV_X = getRandomNumber(min(ROAD_X_COORD_1, ROAD_X_COORD_2), max(ROAD_X_COORD_1, ROAD_X_COORD_1));
		}
		else /*Vertical*/
		{
			ROAD_X_COORD_2 = ROAD_X_COORD_1;
			ROAD_Y_COORD_2 = getRandomNumber(0,m_height - 1);
			for (int i = min(ROAD_Y_COORD_1, ROAD_Y_COORD_2); i < max(ROAD_Y_COORD_1, ROAD_Y_COORD_2); ++i)
			{
				(*m_map)[i][ROAD_X_COORD_1] = new Road(ROAD_X_COORD_1, i);			
			}
			PREV_X = ROAD_X_COORD_1;
			PREV_Y = getRandomNumber(min(ROAD_Y_COORD_1, ROAD_Y_COORD_2), max(ROAD_Y_COORD_1, ROAD_Y_COORD_1));			
		}
	}
	while (getPossibleBuildings() < MIN_NUMBER_OF_BUILDINGS);
	#ifndef NDEBUG
	Print();
	#endif
	/*Generate random buildings next to each road tile*/
	for (int i = 0; i < m_height; ++i)
	{
		for (int j = 0; j < m_width; ++j)
		{
			if ((*m_map)[i][j]->getType() != GRASS)
				continue;
			if (i > 0)
			{
				if ((*m_map)[i-1][j]->getType() == ROAD)
				{
					(*m_map)[i][j] = new House(j,i);
				}
			}
			if (i < m_height - 1)
			{
				if ((*m_map)[i+1][j]->getType() == ROAD)
				{
					(*m_map)[i][j] = new House(j,i);
				}
			}
			if (j > 0)
			{
				if ((*m_map)[j-1][j]->getType() == ROAD)
				{
					(*m_map)[i][j] = new House(j,i);
				}	
			}
			if (j < m_width - 1)
			{
				if ((*m_map)[i][j+1]->getType() == ROAD)
				{
					(*m_map)[i][j] = new House(j,i);
				}
			}
			
		}
	}
	 
}

int Map::getPossibleBuildings()
{
	/*Possible house counting mechanism
	 *This algorithm will use a flag array to check if a spot has already been flagged or not
	 *It will loop through the whole map, checking for roads
	 *When the algorithm finds a road, it will flag all empty spots next to it and increase the counter
	 */
	bool flag[m_height][m_width];
	int buildingCounter = 0;
	/*Loop through map*/
	for (int i = 0; i < m_height; ++i)
	{
		for (int j = 0; j < m_width; ++j)
		{
			/*Check if this point is a road*/
			if ((*m_map)[i][j]->getType() == ROAD)
			{
				/*Now we search for empty, non-flagged spots around this road*/
				
				/*Check all points above this road, so we need to make sure i > 0*/
				if (i > 0)
				{
					/*Check if spots are grass (empty) and make sure they aren't already flagged, so we don't count spots twice*/
					if ((*m_map)[i-1][j]->getType() == GRASS && flag[i-1][j] == false);
					{
						/*Finally, flag this spot and increment the counter*/
						flag[i-1][j] = true;
						++buildingCounter;
					}
				}
				/*Find all spots underneath this road*/
				if (i < m_height - 1)
				{
					if ((*m_map)[i+1][j]->getType() == GRASS && flag[i+1][j] == false);
					{
						flag[i+1][j] = true;
						++buildingCounter;
					}

				}
				/*Find all spots next to this road*/
				if (j > 0)
				{
					if ((*m_map)[i][j-1]->getType() == GRASS && flag[i][j-1] == false)
					{
						flag[i][j-1] = true;
						++buildingCounter;
					}
				}
				if (j < m_width - 1)
				{
					if ((*m_map)[i][j+1]->getType() == GRASS && flag[i][j+1] == false)
					{
						flag[i][j+1] = true;
						++buildingCounter;
					}
				}				
			}
		}
	}
	return buildingCounter;
}
/*Destructor*/
Map::~Map()
{
	//delete dynamically allocated map
	delete m_map;
}
void Map::Print()
{
	for (int i = 0; i < m_height; ++i)
	{
		for (int j = 0; j < m_width; ++j)
			(*m_map)[i][j]->Print(true);
		std::cout << "\n";
	}
	std::cout << "\n\n";
}
On line 92, shouldn't it be ROAD rather than GRASS?

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if ((*m_map)[i][j]->getType() != ROAD)
	continue;
Last edited on
Houses can only be generated on grass, so I suppose Grass is correct. If you change it to road, it will start generating houses on roads. (I've just tried it).

I FOUND IT!
It was a really dumb mistake... And hard to spot!
The following code:
 
if ((*m_map)[j-1][j]->getType() == ROAD) //[j-1][j] 

should be changed to
 
if ((*m_map)[i][j-1]->getType() == ROAD)//[i][j-1] 


I'm happy now :)
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