Build a Rocket Launcher! - Unity 3 Game Development - page 196

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In this secion, we used the Instantiate() funcion to clone a new game object from the
prefab object in the Project view. The Instantiate() funcion takes three parameters,
which are the original Object , Position (Vector3) , and Rotation (Quaternion) . The Position
and Rotation objects are the transform parameters at the start posiion of the object, which
will be created in the scene. The Instantiate() funcion can take any kind of object and
the result can also be returned to any kind of objects. We can also see more examples and
details from the Unity document at:
http://unity3d.com/support/documentation/ScriptReference/Object.
Instantiate.html
http://unity3d.com/support/documentation/Manual/Instantiating%20
Prefabs.html .
Next, we will talk about the Invoke() funcion, which we used to call the funcion ater the
ime we have set in seconds. If some of you have experience with Actionscript , this funcion
is very similar to the setTimeOut() funcion. We can also use InvokeRepeating()
to call the method similar to the Invoke() funcion, but this funcion will repeat calling
that funcion every ime we set in seconds. We can see more details about the Invoke()
funcion from the Unity document at:
http://unity3d.com/support/documentation/ScriptReference/
MonoBehaviour.Invoke.html .
For the InvokeRepeating() funcion, refer to the following website:
http://unity3d.com/support/documentation/ScriptReference/
MonoBehaviour.InvokeRepeating.html .
Finally, let's talk about the posiion of the rocket that launches from the same posiion of
the scope target UI. This is a bit tricky because we want the player to be able to aim and
shoot the rocket exactly to the same posiion that he/she is aiming at. So, we add the
RocketLauncher object as a child of the Main Camera because we want it to move or
rotate with the user view, which is the Main Camera . Then, we add the scope target UI at
the center of the screen because it is easier for the player to aim than than if we put it on
one side. So, we set up the posiions X and Y of RocketLauncher object to 0 because it
is the same posiion to the Main Camera and if we get the posiion of the Main Camera
to the screen posiion it will be the center of the screen. Then, we set up the Z posiion
of RocketLauncher object to 2 because it is the same depth as our character weapon
graphics. This is to make the rocket not too close to the camera. We can also see it from the
following diagram: