[C++/SDL] Tile-Based Collision Detection

[HalfNOoB]

Hi guys

I'm still working on my Project and the next Problem has occured: How do I detect collisions on a tilebased map? My tiles are 16x16 and the map is based on the tutorial of sdltutorials.com (http://www.sdltutorials.com/sdl-maps). I really like this Approach because I can define for each tile of what type it should be (so a earth tile can be walkable and lead to a secret passage).
The first Number stands for what Kind of tile it should be (e.g. Grass, Earth, Water, Blank,...) and the number after ":" stands for the type of the tile (e.g. solid, walkable, do dmg to the Player,...).

e.g.
0:0 0:0 0:0 0:0 0:0 //No tile and walkable
0:0 0:0 0:0 0:0 0:0
0:0 0:0 0:0 0:0 0:0
1:1 1:1 1:1 1:1 1:1 //Grass tile and solid
2:1 2:1 2:1 2:1 2:1 //Earth tile and solid

It's working just fine with loading the Images, but i've got no clue about the collision.
I've already read a lot of stuff on the Internet but I don't get how to Combine it the structure from above. For example lazyfoo describes the collision with one object like one wall. So how can I check the Player Position with each tile?

Do you even have some better ways of doing this? For now there's no camera, but I plan to implement one later...

Thx for your suggestions

Half_NOoB

(EDIT: I'm trying to make a 2D platformer...)

[fabtasticwill]

If you can get the players position, then you could move around in the file to find the tile that the player is on.

[HalfNOoB]

In my CPlayer-class is the x/y-position of the Player in a member variable stored.

int m_PosX;
int m_PosY;

Would you mind going a Little bit more into Detail with your Suggestion?

[fabtasticwill]

You might want to look at using fseek to move around in the file. if you've got the width of the file, you could make a function that gets the text at x and y positions in text files.
psuedo-code

string xyFile(int x, int y,int width, FILE file) {
     string f;
     fseek(width*y+x, file);
     fscanf (file, "%f", &f);
     return f;
}

[HalfNOoB]

Hm i don't understand what you're trying to say...


I've come up with something to get the Playerposition in relation to the tile in the meanwhile:

int TileX = Player.GetPosX() / TILE_SIZE; //--> If the Player X-Coordinate is 320, TileX would be 20
int TileY = Player.GetPosY() / TILE_SIZE; //--> If the Player Y-Coordinate is 160, TileY would be 10

But how can I tell the Computer with which tile he should check for collision?

[ahcfan]

If you move left then check TileX - 1, TileY

If you move down then check TileX, TileY + 1

etc

Check before moving and move only if the tile is walkable.