Libgdx Rectangle Wall Collision

Question

I've been trying to find/create a collision detection for rectangles in Libgdx but I can't seem to get anywhere. I have a rectangle called bucket with width and height 64 and a rectangle called wall with width and height 64. I'm trying to make it so that the player does not pass through the rectangle and can continue on moving while sticking to the wall without phasing through or random teleporting. My method works when there is 1 block but when there is more then one it just breaks and doesn't work.

I know this method is ugly but it is just experimentation

private void checkCollisions(Rectangle bucket, Wall wall){
    if(bucket.overlaps(wall.getRectangle())){
        if(bucket.x > wall.getRectangle().x - 64 && bucket.x < wall.getRectangle().x - 55){
            //collision with right side
            bucket.x = wall.getRectangle().x - 64;
        }
        if(bucket.x < wall.getRectangle().x + 64 && bucket.x > wall.getRectangle().x + 55){
            //collision with left side 
            bucket.x = wall.getRectangle().y + 64;
        }                           
        if(bucket.y < wall.getRectangle().y + 64 && bucket.y > wall.getRectangle().y + 55){
            //collision with top side 
            bucket.y = wall.getRectangle().y + 64;
        }                             
        if(bucket.y > wall.getRectangle().y - 64 && bucket.y < wall.getRectangle().y - 55){
            //collision with bottom side
            bucket.y = wall.getRectangle().y - 64;
        }
    }
}

I would be very appreciative if someone could point me in the correct direction or share some code that would help me.

Ryan Ryan · Accepted Answer · 2017-01-15T03:28:08

In LibGDXwhen looking at collision detection you must first note two important aspects of the default LibGDX Coordinate system.

When you draw a image, Its (x, y) coordinate is the bottom left of the image
(0,0) is the bottom left side of the screen

Using this information we can fix your logic for collisions to the following:

private void checkCollisions(Rectangle bucket, Wall wall){
    if(bucket.overlaps(wall.getRectangle())){
        if(bucket.x + 64 > wall.getRectangle().x && bucket.x < wall.getRectangle().x){
            //collision with right side of bucket
        }
        if(bucket.x < wall.getRectangle().x + 64 && bucket.x > wall.getRectangle().x){
            //collision with left side of bucket
        }                           
        if(bucket.y + 64 > wall.getRectangle().y && bucket.y < wall.getRectangle().y){
            //collision with top side of bucket
        }                             
        if(bucket.y < wall.getRectangle().y + 64 && bucket.y > wall.getRectangle().y){
            //collision with bottom side of bucket
        }
    }
}

This method will determine which side of the bucket detected a collision with the default LibGDX coordinate system.

Libgdx Rectangle Wall Collision

1 Answers