Draw a game object between two objects (for example, a beam), struggling with angle

Questions & Answers
1

Hola!

I’m instantiating a new GameObject from a prefab, which is most often going to be a attack laser/beam/etc. So, I want it to be drawn between two objects (which I call here origin and target).

I figure that beam object should be positioned in a center point between origin and target, and that part works well… and I can also calculate scale based on the distance between the two:

// get the middle point between the objects
Vector3 center = Vector3.Lerp(origin.transform.position, target.transform.position, 0.5F);

Part where I’m struggling with is rotating the beam object so it looks like it’s connecting the origin and target. It’s a 3d space, but angle is 2d since Y plane is fixed.

Here’s the code I’ve had that failed miserably:

// this angle is always too small, while it should go from 0 to 360 or such
float angle = Vector2.Angle(new Vector2(origin.transform.position.x, origin.transform.position.z), new Vector2(target.transform.position.x, target.transform.position.z));

I’ve also tried snippets with Quaternion.FromToRotation, Vector3.Cross, .LookAt, and very much anything I could google with finding angle between two objects.

At this point I’m about to go back to basics and calculate angle myself between two points, just like we did in college, but I hope there’s more elegant solution out there, especially with all built-in Unity functions.

2

You may have an easier time using a LineRenderer or TrailRenderer.

If you really need a manual solution, I’d say this is the sort of problem that’s much easier to solve with vectors directly. For example, you could call LookAt() on the beam object’s transform, forcing it to “face” the target, and then scale the beam object along its forward axis proportional to the distance between shooter and target positions.