PhysicsRaycaster Incorrect Ray Length

Unity Engine
, , , ,
1

I’m struggling with what looks like a bug in the Unity PhysicsRaycaster.

I have a basic test setup with:

  • A Camera, with a PhysicsRaycaster attached
  • A cube as a child of the camera, translated/scaled to cover the camera far plane
  • An EventSystem

Every frame I’m logging out the results from EventSystem.current.RaycastAll. Obviously I should get a hit on my cube every frame, since it covers the entire camera viewport. What I’m actually seeing is no hits on some frames.

I think I’ve narrowed this down to the calculation of the ray length in the PhysicsRaycaster. This code is copied directly from that class:

ray = eventCamera.ScreenPointToRay(eventPosition);
// compensate far plane distance - see MouseEvents.cs
float projectionDirection = ray.direction.z;
distanceToClipPlane = Mathf.Approximately(0.0f, projectionDirection)
    ? Mathf.Infinity
    : Mathf.Abs((eventCamera.farClipPlane - eventCamera.nearClipPlane) / projectionDirection);

If I replicate it in my test script and draw the results I get this:

Unity_2026-01-20_18-23-42
Unity_2026-01-20_18-23-422071×794 127 KB

Unity_2026-01-20_18-24-25
Unity_2026-01-20_18-24-252010×716 109 KB

When the camera is aligned with the Z axis the length is correct, but when the camera is rotated the length is too short and so the PhysicsRaycaster misses some hits.

Is this a bug in the PhysicsRaycaster component (and if so, is there a convenient workaround)? Or am I just doing something dumb?