Transform.Forward dosen't work consistently

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     public void generateTrack()
         {
             print ("generate Track Called");
             
             //Setting the location on next track in line
             nextTrackLocation = currentTrackLocation.forward * 10;
             print ("nextTrackLocation before inst" + nextTrackLocation);
             print ("currentTrackLocation before inst" + currentTrackLocation.position);
             /*
             nextTrackLocation.x = this.gameObject.transform.position.x;
             nextTrackLocation.y = this.gameObject.transform.position.y - 1f;
             nextTrackLocation.z = this.gameObject.transform.position.z + 5f;
             */
             
             
             //print (nextTrackLocation);
             
             //Instancing the next track in line
             GameObject trackInstance = Instantiate(planeStraightPreFab, nextTrackLocation, Quaternion.identity) as GameObject;        
             currentTrackLocation = trackInstance.transform;
             print ("nextTrackLocation after inst " + nextTrackLocation);
             print ("currentTrackLocation after inst" + currentTrackLocation.position);
         }

I'm currently attempting to generate a track 10 units infront of the current track. The first track is predefined and works well but as soon as this function is called again the next track in line will spawn at the previous track's position. The nextTrackLocation = currentTrackLocation.forward * 10; line does not seem to update the location.

Any help would be great. Thanks!

Answer 1

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Answer by Hoeloe · Sep 04, 2013 at 08:25 AM

You're misunderstanding what Transform.forward is. It gives you a direction relative to the transform object. So let's say you have a transform at coordinates (10,10,10), facing along the z-axis. Transform.forward would give you the vector: (0,0,1), which is the direction the object is facing, relative to its position. The problem you are experiencing is that (I assume) all the objects are facing in the same direction, so all your calls to currentTrackLocation.forward give the same vector, which you are then multiplying by 10 and using as the position. Hopefully you can see why they are all being instantiated in the same place. There is a solution, however, and a simple one: I mentioned that the forward vector was relative to the position, so the fix is simple: add the position back on! If you change your code to set the location to this:

  nextTrackLocation = currentTrackLocation.position + currentTrackLocation.forward * 10;

You should get exactly what you need, and hopefully you can see why.

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biggestgeek · Sep 04, 2013 at 08:33 AM 0

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Thanks @Hoeloe! That worked! I've actually solved it by changeing the currentTrackLocation.forward to currentTrackLocation.transform.TransformPoint(Vector3.forward * 10);

Guess that works the same too.

Hoeloe · Sep 04, 2013 at 08:42 AM 0

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That works in pretty much exactly the same way, except that will also take into account the scale of the transform,so if you double the length, the new position will change accordingly - watch out for that.

biggestgeek · Sep 04, 2013 at 09:12 AM 0

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@Hoeloe I have another problem in that I have tracks which curve left and right and right now I have trouble getting them to align properly. Currently they are all just spawning in a straight line even if the track goes left or right.

Any idea how am I to go about doing that?

Hoeloe · Sep 04, 2013 at 09:18 AM 0

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That's because of the forward direction of the object. You'll want to make sure the forward vector (the blue arrow in the editor) is pointing in the direction you want the track to go - that should solve the issue.

Transform.Forward dosen't work consistently

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