How to handle collision detection

Question

So the way that I am doing the movement for my game is that you can left click a unit (which is just a rectangle object), and then it is selected. While it is selected, you can right click and that will be the unit's destination.

This is the process input method:

    public void ProcessInput(Vector2 mouseLoc)
    {
        // SO, I have to take this mouse location, which is the location on the screen
        // And convert it to a "world" coordinate

        Vector2 distance = new Vector2(mouseLoc.X - position.X, mouseLoc.Y - position.Y);

        if (distance.Length() < speed)
        {
            position = mouseLoc;
            isMoving = false;
        }
        else
        {
            distance.Normalize();
            Vector2 toMove = new Vector2((int)(distance.X * speed), (int)(distance.Y * speed));
            position += toMove;
            bounds = new BoundingSphere(new Vector3(position, 0), radius);
        }
    }

I have a basic Wall class that is essentially just another rectangle object but with different properties like textures and what not.

This is my check collision method with the wall:

    public Boolean checkCollision(Wall wall)
    {
        if (wall.Bounds.Intersects(this.bounds))
        {
            Vector2 direction = new Vector2((position.X - destination.X) * -1,
            (position.Y - destination.Y) * -1);
            direction.Normalize();
            position += direction * 5;
            destination = position;
            return true;
        }
        return false;
    }

The problem is that the unit just kinda gets stuck in the wall when it hits it. I'm wondering what is the best way to fix this problem. I know that I have to move the unit out of that spot, but I'm not sure how to.

Any thoughts on how to handle this are appreciated.

Answer 1

I do not know which physics engine you are using but generally , if you want to things go smooth you have two decent ways:

• Dynamically, use forces to move and let the engine handle the collisions.
• Kinematically, use your own calculations to move and handle collisions.

If you use kinematics for some of the huge bodies (you have to use kinematics for small bodies like bullets generally) and dynamics for other there will be wrong collision responses.

The answer to your question is generally, make the dynamic object kinematic on collision and move it backwards. When it is not collided anymore make it dynamic again.