So I am writing a game in C++, and its a lot like Zelda . The way I am storing the maps information is through an array which contains which blocks are walkable and which are not. It rounds the players position to the nearest multiple of 32 which is the size of a tile/square.

    void walk(int i, int j,char* collide)
    {
        int tempx,tempy;
        animate = true;
        //DOWN LEFT RIGHT UP
         tempx=x+hspeed*i;
        tempy=y+vspeed*j
        float xadj,yadj;
        xadj = ceil(float(tempx)/32.0);
        yadj = ceil(float(tempy)/32.0);
        int boundboxes [8];
        if(j < 0)
        {
            yadj -=1;
            face = UP;
        }
        else if(j > 0)
        {
            face = DOWN;
        }
        else if (i < 0)
        {
            xadj-=1;
            face = LEFT;
        }
        else if (i > 0)
        {
            face = RIGHT;
        }
        if(collide[int(xadj+(yadj)*20)]==0)
        {
            x = tempx;
            y = tempy;
        }

    }

So the problem i am having is here I cannot walk through the gap between the tree and the mountains, and there are several other false detections like being able to walk through trees if you are technically not on the tree tile. Can I have some help with this please?

Here's a thought: If the player is at (90,90), he's basically almost entirely covering tile (3,3), but dividing by 32 will give you (2,2) - the wrong tile.

I think you'd get better results if you divided from the center of the player's sprite, rather than the top-left corner.

So you'd go:

const int TileWidth = 32;
const int TileHeight = 32;

const int PlayerWidth = 32;
const int PlayerHeight = 32;

int tileX = ceil((posX + (PlayerWidth/2)) / TileWidth);
int tileY = ceil((posY + (PlayerHeight/2)) / TileHeight);

After you get that working, I'd even suggest tweaking it to be the horizontal center of the sprite, but 3/4 of the height of the sprite, so the "center" of the sprite is closer to the sprite's feet.

const int PlayerWidth = 32;
const int PlayerHeight = 32;

const int SpriteOriginX = (PlayerWidth/2);
const int SpriteOriginY = int(float(PlayerHeight) * 0.75f);

int tileX = ceil((posX + SpriteOriginX) / TileWidth);
int tileY = ceil((posY + SpriteOriginY) / TileHeight);

Thank you both for your suggestions, when I go back to work on it I will take it into account. I will return to show you guys how goes.

Why are you using floating point numbers if all positions are snapped to a grid? That seems just ripe for problems.

What are i and j? They look like variables representing x and y movement direction, in which case they should have more descriptive names that properly describe their purpose.

It should be fairly straightforward to put a breakpoint on this code and step through it to see where you're getting unexpected values. Have you tried that yet?

I'm assuming it's because they want to show movement between tiles, though for the actual "Can I move to grid space X,Y" check, you're right, that should be integer, though I'm guessing they wrapped this conversion from the units floating point position to integer values into their check.

So I have sort have fixed the problem, a big thank you to Servant of the Lord. So there is solid collision detection which is all fine and dandy, the only problem is with walking towards a tile from the left,right and on top what happens is Link overlaps the tree, which could be any non-walkable tile. How can I fix my code, that way I can have Link not overlap on the tile from any direction other than approaching a non-walkable tile from the bottom. The image attached will illustrate what I mean. And here is the code.

void walk(int i, int j,char* collide)
    {
        const int PlayerWidth = 32;
        const int PlayerHeight = 32;
        const int TileWidth = 32;
        const int TileHeight = 32;
        const int SpriteOriginX = (PlayerWidth/32);
        const int SpriteOriginY = int(float(PlayerHeight) * 0.50f);
        int xpos,ypos;
        animate = true;
        //DOWN LEFT RIGHT UP
        xpos=x+hspeed*i;
        ypos=y+vspeed*j;
        int xtile = ceil((xpos + SpriteOriginX) / TileWidth);
        int ytile = ceil((ypos+ SpriteOriginY) / TileHeight);

        if(j < 0)
        {
            face = UP;
        }
        else if(j > 0)
        {
            face = DOWN;
        }
        else if (i < 0)
        {
            face = LEFT;
        }
        else if (i > 0)
        {
            face = RIGHT;
        }
        if(collide[int(xtile+(ytile)*20)]==0)
        {
            x = xpos;
            y = ypos;
        }

    }

Well guys, I have resolved the issue. First off I would like to thank Servant of the Lord for helping me with collision and NoAdmiral for giving me advice on with aabb collision checks. However rather than using the edges of the boxes for collision I used the four corners of the box to check for collision, so here is what I have for the collision check,

void walk(int i, int j,char* collide)
    {
        bool collision = false;
        const int TileWidth = 32;
        const int TileHeight = 32;
        int xpos,ypos; //Players actual x position and y position
        int xtile,ytile;//Player's position with respect to tile
        animate = true;
        //DOWN LEFT RIGHT UP
        xpos=x+hspeed*i;//moving x
        ypos=y+vspeed*j;//moving y
        xtile = ceil((xpos + 4) / TileWidth);//figures out which tile top left corner is in(x component)
        ytile = ceil((ypos + 16) / TileHeight);//figures out which tile top left corner is in(ycomponent)
        if(collide[int(xtile+(ytile)*20)]!=0)//checks if the tile is occupado
        {
            collision = true;
        }
        xtile = ceil((xpos + 28) / TileWidth);//figures out which tile top right corner is in(x part)
        if(collide[int(xtile+(ytile)*20)]!=0)
        {
            collision = true;
        }
        ytile = ceil((ypos + 28) / TileHeight);//figures out which tile bottom right corner is in(y component)
        if(collide[int(xtile+(ytile)*20)]!=0)
        {
            collision = true;
        }
        xtile = ceil((xpos+4) / TileWidth);//figures out which tile bottom left corner is in(x component)
        if(collide[int(xtile+(ytile)*20)]!=0)
        {
            collision = true;
        }
        if(j < 0)
        {
            face = UP;
        }
        else if(j > 0)
        {
            face = DOWN;
        }
        else if (i < 0)
        {
            face = LEFT;
        }
        else if (i > 0)
        {
            face = RIGHT;
        }
        if(!collision)//if there is not a collision the player can move
        {
            x = xpos;
            y = ypos;
        }
    }

Once again thank you guys for the help.