I’m trying to make a grappling hook style game in Unity. When the rope collides with an object, I move the anchor point to that position and save a List<Vector2> of positions.

I’m at the point now where I need to remove the last anchor based on the angle between the player and the last anchor and the last anchor and the second to last anchor.

Here’s a crude drawing to demonstrate:

• A is the original anchor Point.
• B is the recent anchor Point
• Green is the player

In this example, there should be no detaching. However, if the angle between the player and B is the same or less than the angle between B and A, it should detach:

I’m struggling to pin down the logic here, and I fear I’ve spent so long on this that I’m starting to overcomplicate things.

Here’s the current logic that I’m using, which works 80% of the time:

Vector2 playerPosition = player.transform.position;
Vector2 lastAnchor = anchorPositions[anchorPositions.Count - 1];
Vector2 secondToLastAnchor = anchorPositions[anchorPositions.Count - 2];

Vector2 directionToLastAnchor = lastAnchor - playerPosition;
Vector2 directionToSecondToLastAnchor = secondToLastAnchor - lastAnchor;

bool anchorToLeftOfPlayer = directionToLastAnchor.x < 0;
bool anchorToRightOfPlayer = directionToLastAnchor.x > 0;

float angleToLastAnchor = Vector2.SignedAngle(playerPosition, lastAnchor);
float angleToSecondToLastAnchor = Vector2.SignedAngle(secondToLastAnchor, lastAnchor);

if (anchorToLeftOfPlayer) {
    if (angleToLastAnchor > angleToSecondToLastAnchor && directionToLastAnchor.x > directionToSecondToLastAnchor.x) {
        Debug.Break();
        DetachRopeAtIndex(anchorPositions.Count - 1);
    }
} else if (anchorToRightOfPlayer) {
    if (angleToLastAnchor < angleToSecondToLastAnchor && directionToLastAnchor.x < directionToSecondToLastAnchor.x) {
        Debug.Log("Detached because anchor on right of player");
        Debug.Break();
        DetachRopeAtIndex(anchorPositions.Count - 1);
    }
}

Here’s a human readable variation:

If anchor to the right of the player and angle B < angle A and direction B < direction A = DETACH

This breaks with the following scenario:

I’m not completely sure that I’m

• Calculating the angles correctly
• Applying the right logic
• Not overcomplicating things
• Not handing off this logic to Unity