[SOLVED] Collision Issue on TiledMap (Slick2D)

Newbie & Debugging Questions
#1

Hello.
I’ve tried my best to make this collision work, but I simply can’t. I tried every method, even copied the code from internet tutorial, but it simply won’t work. It seems as if when the player is in the middle of two tiles, it won’t work. Uh, I don’t know how to explain it right, so I’ll post some screenshots.

It works if the player is in a “full” tile.
Click here to see the screenshot.

But, if a player is kind of in a “half” tile, it doesn’t.
Click here to see the screenshot.

The code I use to check for the collision:

	public void update(int delta, int direction, Map map){
		speed = 0.2f; // Just for testing purposes. Will remove later.
		switch(direction){
			case 1: // Up
				sprite = up;
				if(!map.isBlocked(x, y - delta * speed)){
					y -= delta * speed;
				}
				break;
			case 2: // Down
				sprite = down;
				if(!map.isBlocked(x, y + Constants.TILE_SIZE + delta * speed)){
					y += delta * speed;
				}
				break;
			case 3: // Left
				sprite = left;
				if(!map.isBlocked(x - delta * speed, y)){
					x -= delta * speed;
				}
				break;
			case 4: // Right
				sprite = right;
				if(!map.isBlocked(x + Constants.TILE_SIZE + delta * speed, y)){
					x += delta * speed;
				}
				break;
			default:
				System.err.println("Invalid direction.");
				break;
		}
	}

My isBlocked(float, float) method (in Map class) is pretty simple:

	public boolean isBlocked(float x, float y){
		int xTile = (int) (x / 32);
		int yTile = (int) (y / 32);
		return blocked[xTile][yTile];
	}

NOTE: In my map class I set up stuff with TiledMap, just so you know.

#2

You are doing the collision checking wrong.

You are checking a + instead of a square.

What you need to do is to store the movements in a different variable (say, velX and velY), then check te bounds by axis. To check by axis you first check the coords (x, y+velY) then the coords (x+velX, y) or vice versa.

To check the bounds, you check each of the following coordinates:


x
y
x+sizeX
y+sizeY

And if any of them is blocked, don’t do the movement for that axis.

#3

Actually, my collision checking method was correct, but I used it in a wrong context, for the lack of a term. My new method of doing it is drawing rectangles on the blocked tile spots. Maps gets drawn on top of those rectangles, so they’re not visible. It works like a charm!

Here’s the code:

	public boolean collides(float x, float y, Graphics g){
		Rectangle player = new Rectangle(x, y, 32, 32);
		g.draw(player);
		for(int i = 0; i < rects.size(); i++){
			if(player.intersects(rects.get(i))){
				System.out.printf("Collision detected at (%s, %s).\n", x, y);
				return true;
			}
		}
		System.out.printf("No collision has been detected.\n");
		return false;
	}

Thank you for your help, anyway!