java - get direction of rectangle collision

Question

I'm working at a tiled game. I want to check the direction where the tiled is from the player, when is colliding.

static public boolean intersectRectangles(Rectangle rectangle1, Rectangle rectangle2, Rectangle intersection) {
    if (rectangle1.overlaps(rectangle2)) {
        intersection.x = Math.max(rectangle1.x, rectangle2.x);
        intersection.width = Math.min(rectangle1.x + rectangle1.width, rectangle2.x + rectangle2.width) - intersection.x;
        intersection.y = Math.max(rectangle1.y, rectangle2.y);
        intersection.height = Math.min(rectangle1.y + rectangle1.height, rectangle2.y + rectangle2.height) - intersection.y;
        return true;
    }
    return false;
}

I want this function to return 0 if there is no collision

1 = rect1 is in the left

2 = rect1 is in the right

3 = rect1 is in the bottom

4 = rect1 is in the top

Like this pic:

enter image description here

I tried doing this

// if there is a collision between player and tile
float xdif = player.x + 40 - j * 40;
float ydif = player.y + 40 - i * 40;
Direction direction = Direction.RIGHT;
if (Math.abs(xdif) > Math.abs(ydif)) {
    if (player.y > i * 40)
        direction = Direction.DOWN;
    else
        direction = direction.UP;

} else {
    if (player.x > j * 40)
        direction = Direction.LEFT;
    else
        direction = direction.RIGHT;
}

But is not working..

[This example](http://stackoverflow.com/questions/13261767/java-ball-object-doesnt-bounce-off-of-drawn-rectangles-like-its-supposed-to/13263022#13263022) might help — MadProgrammer, Feb 08 '14 at 22:22

bcorso · Answer 1 · 2014-02-08T23:07:00.770

This assumes a bottom-left origin coordinate system (x￫, y￪)

static public int intersectRectangles(Rectangle player, Rectangle tile) {
    if(!player.overlaps(tile))
        return 0;      

    Double pL = player.x,             //left
           pR = pL + player.width,    //right
           pT = player.y,             //bottom
           pB = pT + player.height;   //top

    Double tL = tile.x,               //left
           tR = tL + tile.width,      //right
           tT = tile.y,               //bottom
           tB = tT + tile.height;     //top

    Double inf = Double.MAX_VALUE;
    List<Double> intersect_diffs = new ArrayList<Double>(new Double[] {inf,inf,inf,inf});

    if(pR > tL && pL < tL)             // Player on left
        intersect_diffs[0] = pR - tL;
    if(pL < tR && pR > tR)             // Player on Right
        intersect_diffs[1] = tR - pL;
    if(pT > tB && pB < tB)             // Player on Bottom
        intersect_diffs[2] = pT - tB;
    if(pB < tT && pT > tT)             // Player on Top
        intersect_diffs[3] = tT - pB;

    // return the closest intersection
    return intersect_diffs.indexOf(Collections.Min(intersect_diffs));
}

Hmm, the origin is in the bottom left – Boldijar Paul Feb 08 '14 at 22:52 — Boldijar Paul, Feb 08 '14 at 22:52

java - get direction of rectangle collision

1 Answers1