/// <summary>
/// Launches a new ball in a direction between the negative and positive maxLaunchAngle with respect
/// to the paddles transform up. A ball is only launched if a prefab with a ballcontroller is
/// set up in the inspector.
/// </summary>
private void LaunchBall()
{
if (ball == null)
{
ball = Instantiate(ballPrefab);
ball.transform.position = transform.position + transform.up * 0.5f;
BallController ballController = ball.GetComponent <BallController>();
if (ballController != null)
{
ballController.Owner = this.gameObject;
float angle = Random.Range(-maxLaunchAngle, maxLaunchAngle);
Vector3 direction = Quaternion.AngleAxis(angle, transform.forward) * transform.up;
ballController.SetDirection(direction);
}
}
}
/// <summary>
/// This is where the magic happens. The paddle has an affect on the ball depending on the
/// paddle surface material. Since this method comes after fixed update the collision will
/// already be resolved before this event. This event is therefore a correction of
/// collision event.
/// </summary>
/// <param name="collision"></param>
private void OnCollisionEnter2D(Collision2D collision)
{
BallController ball = collision.gameObject.GetComponent <BallController>();
if (ball != null)
{
Rigidbody2D ballBody = collision.rigidbody;
if (ballBody != null)
{
ContactPoint2D contactPoint = collision.GetContact(0);
// We check if the collision normal is equal to the paddles transform up.
// This is the case where we can do fun stuff with the ball reflections
// Note that the == operator for Vector2s and Vector3s is an
// approximatly equal operator.
if (contactPoint.normal == -(Vector2)transform.up)
{
// We find the position of the top center of the collider. This takes rotation
// into consideration
Vector2 topMiddle = paddleCollider.bounds.center + transform.up * paddleCollider.size.y / 2;
// We find the distance between the contact point and the paddle top center
Vector2 distance = topMiddle - contactPoint.point;
// We find the signed length from the contact point. We must cast to vector3 to be able to find the sign. We use the
// cross product to see if the contact point is to the left or right of the transform up.
float signedLength = Mathf.Sign(Vector3.Cross((Vector3)distance, (Vector3)contactPoint.normal).z) * distance.magnitude;
if (material != null)
{
// We calculate the new angles added by the collision point from the ball and the paddle velocity
float posAngle = material.CalculateAngleToAddFromCollision(signedLength, paddleCollider.size.x / 2);
// Calculate the new direction of the ball. Remember, the balls velocity is already reflected from the fixed update, so we
// must add the angles in a way that is consistent with the outward velocity.
Vector3 ballDirection = ballBody.velocity;
Vector3 newDirection = Quaternion.AngleAxis(posAngle, transform.forward) * ballDirection;
ball.SetDirection(newDirection);
}
}
}
}
}