Question by Harko33 · Jul 06, 2012 at 07:49 PM · raycast local world normal

Difference between local space normal and world space normal

Hi,

I use raycasting to get the normal of the terrain hit by the ray. This normal is in world space, with the point of the terrain hit by the ray as origin (correct me if I'm wrong). In case I transform this normal in local space with Transform.InverseTransformDirection, which is the origin of the normal ? In which case is it relevant to make this transformation ?

Thanks

Add comment · Show 2

Kryptos · Jul 06, 2012 at 09:16 PM 1

A normal is a vector. There is no such thing as origin.

AlucardJay · Jul 06, 2012 at 09:28 PM 0

you could do some testing and debugging to see what is happening.

 var ray = Camera.main.ScreenPointToRay (Input.mousePosition);
 var hit : RaycastHit;
 if (Physics.Raycast (ray, hit,)) 
 {
     Debug.Log ("origin " + ray.origin + " : hit point " + hit.point + " : hit normal " + hit.normal);
     Debug.DrawLine (ray.origin, hit.point);
 }

there might be more information in the docs :

http://docs.unity3d.com/Documentation/ScriptReference/RaycastHit-point.html

http://docs.unity3d.com/Documentation/ScriptReference/RaycastHit-normal.html

http://docs.unity3d.com/Documentation/ScriptReference/Physics.Raycast.html

http://docs.unity3d.com/Documentation/ScriptReference/Debug.DrawLine.html

Edit : sry, should've included that.