Instantiate based on camera axes

Unity Engine
1

Hello, everyone.

I’m working on a project in Unity that requires the creation of several objects in line with the camera’s position at any given moment - that is to say, the camera is free to rotate around the scene, but I need to instantiate a formation of objects based on the direction it’s pointing at any moment. These objects then move in several different directions.

I got the camera to work like I need it in the first place by making it a child of a “Camera Field” object and making that rotate instead of moving the camera around and trying to force it to stay locked on to a specific point (it’s an orbital camera).

However, now I’m using the following code to instantiate the Rigidbodys I need:

var dot1 = Instantiate(oneOfTheFinickyObjects, playerCam.localPosition + Vector3(0,0,19.5), transform.rotation);

then I set their velocities and send them on their way.

I didn’t anticipate that, because the camera is a child object, playerCam.localPosition never changes. Since these objects are spawned in world space, they are always relative to the world axes and thus they don’t go where I need them (so that their formation faces the camera).

I looked at this thread:
http://forum.unity3d.com/threads/30654-SOLVED-Instantiate-as-child
but, if I combine the solution there with my above code, I just have a bunch of child objects that are still in the wrong places, because they’re still being instantiated in world space.

TL;DR version: I need to tell some objects to spawn N units in front of the camera along the camera’s own Z-axis without taking the camera out of its parent object. Please tell me, is there a way to do this?

Sincerely,
JA

2

ScreenToWorldPoint fed with the center of the screen.

3

I’m not sure that’s the optimal solution here. It sounds like the OP just wants to spawn some objects at positions relative to a particular transform, in which case Transform.TransformPoint() or Transform.forward would probably be more suitable. E.g. (untested):

spawnPosition = transform.TransformPoint(new Vector3(0f, 0f, 10f));
// Or...
spawnPosition = transform.position + transform.forward * 10f;
4

Alright, long story after this.

First off, Jesse, thanks for your help. I hadn’t thought of using the vectors directly (HERP DERP).

I realized that the question I originally asked wasn’t generalizable and thus I had a problem if I tried spawning the particles anywhere other than directly in front. Then I did the obvious: I put up target objects and set their rotation to that of the camera, then instantiated using (yes!) the directional vectors of the target.

Works great now.