A common gotcha when working with Scene.Trace.Ray is misunderstanding what the second Vector3 argument actually represents.

The signature looks like this:

Scene.Trace.Ray( Vector3 from, Vector3 to )

Both arguments are absolute world positions. from is where the ray starts, and to is where the ray ends.

The Mistake

It’s easy to assume the second argument is a direction, and write something like this:

var tr = Scene.Trace.Ray( Scene.Camera.WorldPosition, Scene.Camera.WorldRotation.Forward * 1000f )
    .Run();

Scene.Camera.WorldRotation.Forward * 1000f is not a world position - it’s a direction vector scaled to a length of 1000 units relative to the world origin. This means the ray will trace from the camera’s world position to a point 1000 units in front of the world origin, which is almost certainly not what you want.

Depending on where your camera is, this can produce results that appear to work near the origin but break entirely when the camera moves further away.

To further confuse this, a float implicitly converts to a Vector3 with that value in all components, so if you did this:

var tr = Scene.Trace.Ray( Scene.Camera.WorldPosition, 1000f )
    .Run();

You would get a ray from the camera’s world position to the point (1000, 1000, 1000) in world space, which is almost certainly not what you intended.

The Fix

Add the direction offset to the starting position so the result is an absolute world position:

var tr = Scene.Trace.Ray( Scene.Camera.WorldPosition, Scene.Camera.WorldPosition + Scene.Camera.WorldRotation.Forward * 1000f )
    .Run();

Now the ray traces from the camera position to a point 1000 units directly in front of it in world space, regardless of where the camera actually is.

Quick Reference

Second argument What it means
Scene.Camera.WorldRotation.Forward * 1000f Point 1000 units from the world origin — wrong
Scene.Camera.WorldPosition + Scene.Camera.WorldRotation.Forward * 1000f Point 1000 units in front of the camera — correct

The same rule applies to any Scene.Trace.Ray call — always pass an end position, never a bare direction.

You can also use the Ray struct to construct rays with a direction and length, which can be more convenient:

var ray = new Ray( Scene.Camera.WorldPosition, Scene.Camera.WorldRotation.Forward );
var tr = Scene.Trace.Ray( ray, 1000f )
    .Run();