How to minimalize the time to load Vectors? - c++

Question

I´m currently trying to develop a game and im having some trouble with the Map.
The Map works the Following way: We have a class named Map, which will contain a vector of Tiles.
class GMap
{
private :
std::vector <BTiles> TileList;
...
So, there will be a function Load in GMap which will load all the tiles from a txt file.
All the tiles have their own function, like render for example. And their own variables, like ID and Type of Tile.
I can easily render the tiles, but my problem is that, since the maps are kind of big, and each tile is only 16x16 pixels, it takes a lot of them to fill the whole Surface. And since there are so many of them, it takes way too long to load it. Like, 30-40 seconds for a small part of them.
I still havent developed the code that actually reads the txt file, which will contain the information of how many tiles to load, which types are them and their position, so i have been using this code to test the Tile Rendering.
bool GMap::Load(char *File)
{
int XRand;
for(int i = 0;i < 1024;i++) //I need 1024 tiles to load a screen of 512x512 pixels.
{
BTiles NewTile; //Btile is the Tiles Class.
XRand = rand() % 5; //There are currently only 5 types of Tile. And i wanted to print them randomly, just for testing.
NewTile.OnLoad(XRand, i); //This will be setting type = Xrand, and ID = i. The Type will define which block to print on the screen. And the ID will define where to print it.
TileList.push_back(NewTile);
}
return true;
}
This is the Tiles OnLoad function:
bool BTiles::OnLoad(int BType, int BID)
{
if((BSurface = Surface::OnLoad("BTexture.png")) == false)
return false;
Type = BType;
ID = BID;
return true;
}
I can then print all of the tiles the following way:
void GMap::Render(SDL_Surface *MainSurface)
{
for(int i = 0;i < TileList.size();i++)
{
TileList[i].OnRender(MainSurface); //I am calling a Render function inside the Tile Class. MainSurface is the primary surface im using to render images.
}
But My problem is in the Load Function. It takes way too much time to load those 1024 Tiles. And 1024 tiles are only a few of the amount i will actually have to load in a serious map. Besides, it wont even load them all. After the huge amount of time it takes to "load" the 1024 tiles, it only prints like, half of them. Like, the screen isnt complete with tiles, even though i "loaded" the correct amount to fill the whole screen. I then proceeded to increase the number from 1024 to 2048, in hope that it would finish the screen. But it didnt, in fact, it changed NOTHING. Its like, it loads certain amount, and then it just stops. Or at least it stops rendering.
If anyone wants to know how the rendering is made, i have a Global function which will do the work, and then, on the Tile Class, i have this function:
void BTiles::OnRender(SDL_Surface *MSurface)
{
int X = (ID * 16) % M_WIDTH; //Since i am only using the ID to know which position to put a Tile, i use this function to locate which Horizontal Position to put them. M_WIDTH is a global variable that defines the Width of the screen, it is currently 512
int Y = ((ID * 16) / M_HEIGHT) * 16; //The same but for the Vertical Position. M_HEIGHT is currently also 512
Surface::OnDraw(MSurface, BSurface, X, Y, (Type * 16) % M_WIDTH, (Type * 16) / M_HEIGHT, 16, 16); //This means Render(On The Primary Surface, using the Images on the BSurface, on the Position X, on the position Y, Where the Tile i want to render starts on the X line, Where the Tile i want to render starts on the Y line, it is 16 bits Width, it is 16 bits Height
}
I apologize i didnt explain properly the last function, but i dont think my problem is there.
Anyway if anyone need more info, in a part of the code, just ask.
Thank you!

Answer 1

I Discovered the Problem. Each tile had its own Surface, which would load the same image. That means that i was generating 1024 surfaces, and loading 1024 surfaces. What i did to solve the problem was to create a Surface in the Map Class, which would be used by all Tiles.
So
bool BTiles::OnLoad(int BType, int BID)
{
if((BSurface = Surface::OnLoad("BTexture.png")) == false)
return false;
Type = BType;
ID = BID;
return true;
}
became
bool BTiles::OnLoad(int BType, int BID)
{
Type = BType;
ID = BID;
return true;
}
In The Map Class i added the MSurface, which would load the Image that would contain all Tile Blocks.
And then to render i would do the following:
void GMap::Render(SDL_Surface *MainSurface)
{
for(int i = 0;i < TileList.size();i++)
{
TileList[i].OnRender(MainSurface, MSurface, 0, 0);
}
}
Msurface is the Surface that contained the Image.
And each tile would receive MSurface as an external surface, yet it would be used to hold all images.
Therefore instead of creating 1024 Surfaces, i only created 1. Now it takes 2 seconds to load a lot more than it would before. It also fixed my problem of the Not-Rendering all Tiles.