Detecting front of a collision

Questions & Answers
1

Hey guys^^

I’m working on a 2D topdown game with a 8-way movement. And now I want to check if the collisioning object that touches my player is in front of him or not. (Thats for stop movement and so on)

I wrote the following script. It’s query the direction in which the player look and increase it. Than it compares the new value with the old and compares the oldposition and the position of the colliding object.

It works but sometimes it gives the false value. Is there an logic error or something I don’t see?^^

Thank you so much for your help :slight_smile:

    	void OnCollisionStay2D(Collision2D obj) {
    		Vector2 objPos;
    		Vector2 myPos;
    		Vector2 dirVec;
    		float newX;
    		float newY;
    		
    		objPos = obj.transform.position;
    		myPos = transform.position; 
    		dirVec = new Vector2(0,0);
    	
    		switch (movement.direction) {    
 //(1=Down, 2=Up, 3=Left, 4=Right, 5=UpRight, 6=DownRight,7=DownLeft and 8= UpLeft)

    		case 1:
    			dirVec = new Vector2(0,-1);
    			break;
    		case 2:
    			dirVec = new Vector2(0, 1);
    			break;
    		case 3:
    			dirVec = new Vector2(-1, 0);
    			break;
    		case 4:
    			dirVec = new Vector2(1, 0);
    			break;
    		case 5:
    			dirVec = new Vector2(1, 1);
    			break;
    		case 6:
    			dirVec = new Vector2(1,-1);
    			break;
    		case 7:
    			dirVec = new Vector2(-1,-1);
    			break;
    		case 8:
    			dirVec = new Vector2(-1, 1);
    			break;
    		}
    
    		newX = (myPos.x + dirVec.x);
    		newY = (myPos.y + dirVec.y);
    
    		if (((myPos.x < newX) && (myPos.x > objPos.x)) ||
    		    ((myPos.x > newX) && (myPos.x < objPos.x)) || 
    		    ((myPos.y < newY) && (myPos.y > objPos.y)) ||
    		    ((myPos.y > newY) && (myPos.y < objPos.y))) {
    			Debug.Log ("Object is in front");
    		} else {
    			Debug.Log ("Object is NOT in front");
    		}
    
    }

EDIT:
I edited the script a bit so it works better, but still is a logic error in the query.

2

There is an answer at the following link that detects what side of a 2D box collider is hit. I think that is the best solution for what you are looking for.

3

You can always stick 4 thin colliders as children on the object called front,left,right,back
whichever one detects the collision, that’s the side the collision occured on.

4

Okay I got it^^

I’ve wrote a new script, which sends a raycast in my movement.direction and when something hits this ray my player stops. I can’t believe it it was so simple and work perfectly^^

But I want to thank you all for your great help^^!