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Here is the code I use to create and print my map to the canvas:

var board = [];
function loadMap(map) {
    if (map == 1) {
        return  [

            [2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,3,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,3,3,3,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,3,0,0,2],
            [2,0,0,0,0,0,0,3,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,3,3,0,0,0,0,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,3,3,0,0,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,3,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,3,0,3,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,3,3,3,3,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,3,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,3,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,3,3,3,3,3,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,3,3,0,0,3,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,3,0,0,0,0,0,0,0,0,3,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,3,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,3,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,3,3,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,3,3,3,3,3,3,3,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,3,3,3,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,2],
            [2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2]
        ];
    }
}

board = loadMap(1);
enterfor (y = 0; y <= viewHeight; y++) {
        for (x = 0; x <= viewWidth; x++) {
            var theX = x * 32;
            var theY = y * 32;
            context.drawImage(mapTiles[board[y+viewY][x+viewX]], theX, theY, 32, 32);
        }
    } 

And here is the code I use for player movement:

canvas.addEventListener('keydown', function(e) {
    console.log(e);
    var key = null;
    switch (e.which) {
        case 37:
            // Left
            if (playerX > 0) playerX--;

            break;
        case 38:
            // Up
            if (playerY > 0) playerY--;
            break;
        case 39:
            // Right
            if (playerX < worldWidth) playerX++;
            break;
        case 40:
            // Down
            if (playerY < worldHeight) playerY++;
            break;
    }

viewX = playerX - Math.floor(0.5 * viewWidth);
    if (viewX < 0) viewX = 0;
    if (viewX+viewWidth > worldWidth) viewX = worldWidth - viewWidth;


    viewY = playerY - Math.floor(0.5 * viewHeight);
    if (viewY < 0) viewY = 0;
    if (viewY+viewHeight > worldHeight) viewY = worldHeight - viewHeight;


}, false);

What I am looking for is a method for when the player lands on tile 3 he loses health.

I have tried to use this in the player movement but it doesnt seem to work e.g the left movement:

case 37:
            // Left
            if (playerX > 0) playerX--;
            if(board[x2 - 1] == 3)
            {
                health--;
                playerX--;
            }

EDIT

Im nearly there guys but for some reason the board position my player should be at isnt coming out correct, yet if i print the array it shows the correct value

case 37:
            // Left
            if (playerX > 0) {
                playerX--;
                alert(board[playerX][playerY])
                alert(board);
            };

            if(board[playerX][playerY] == 3){


            }

Heres the code with the alerts to help my explanation, if i can figure out why the players position thinks its somewhere else, i should be able to implement my idea

Thanks

share|improve this question
    
if (playerX > 0) playerX--; if(board[x2 - 1] == 3) { health--; playerX--; } Ok... but what is x2 ?? it is playerX that you just changed, not x2... Not to mention that you use map as a 1D array, when in fact it is a 2D array... Perfect mess ?? –  GameAlchemist Nov 27 '12 at 20:02
    
Seems too simple to be of use to a future reader. –  Anko Dec 8 '12 at 12:05
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1 Answer

I would check if the player moved, and call an event to handle all the checks for new tiles. Something like:

...

if(playerX != oldPlayerX || playerY != oldPlayerY) {
    onTileChange(player);
}

...


onTileChange(Character character) {
    int characterTile = getTileAt(character.positionX, character.positionY);
    switch(characterTile) {
       case 3:
          character.subtractHealth(1);
          break;
    }
}

This example also shows making the player into an extension of a character object. This means you can use this same method for other creatures in your game too. Plus it puts things in a common place, so for example the subtractHealth() function can do the following for characters:

subtractHealth(int amount) {
    health -= amount;
    if(health < 0)
      triggerCharacterDeath(this);
}

Then you don't have to repeat that code everywhere that you subtract health. Makes for cleaner code.

share|improve this answer
    
i cant seem to implement what you are saying. I have implemented the health function and it works fine so thankyou for that. But is there an easier way to check if my player is on a certain tile?? thankyou –  Tom Burman Nov 23 '12 at 19:09
    
You would have to be more specific about what you're having trouble implementing. I have no idea how to make it easier if I don't know what you're having trouble with. –  Byte56 Nov 23 '12 at 19:35
    
the first part of the code you posted, implementing that into my code. Im not great with coding javascript right now –  Tom Burman Nov 23 '12 at 19:38
    
Work on it for more than an hour. Look up how to implement functions/methods. Look up how to create classes/objects. This isn't the stuff you want to skimp on. –  Byte56 Nov 23 '12 at 19:41
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