In this second part of the Introduction to Unity tutorial you'll learn: "How to use the Project window to import and organize your assets", "The difference between GameObjects and Prefabs", "How physics work in Unity", "How cameras work and which types of projections are available" and "The basics of Materials in Unity".
I did the 2016 version of the tutorial and had a problem. Then I saw this updated version and tried it, but I’m having the same problems.
When the game starts, the asteroids don’t always generate on the same plane, so eventually I get 5 asteroids floating around, and they can’t be destroyed. This doesn’t happen to all of them, however, some are able to be shot.
I am getting this error, which I think is related: “UnassignedReferenceException: The variable screenDebris of GameManager has not been assigned.
You probably need to assign the screenDebris variable of the GameManager script in the inspector.
GameManager.Update () (at Assets/Scripts/GameManager.cs:31)”
Also, when I build the game and run it, there is no way to escape from the game back to the computer. I have to re-start the computer.
Currently I am doing this on a MacBook with OS 10.12.3 installed, and Unity 5.5.1f1 personal (64Bit).
Thanks,
Haole
Hi Haole,
Thank you for taking the time to have another crack at the updated tutorial! Let’s see if we can help get to the bottom of what’s going wrong.
Asteroids spawning on the wrong plane occasionally:
Troubleshooting is sometimes best done in Unity’s Scene View.
Open your project in Unity
In the Hierarchy, double click on “Spaceship” to zoom into the spaceship in the scene view.
In the Scene view click the red “X axis” on the control at the top right of the window.
You should be looking at you spaceship from the side now.
Zoom out a little using the scroll wheel (or hold down Ctrl and Alt, right-click and move the mouse down to zoom out) and click play to preview your game…
Ignore the Game view and watch the Scene view. Are the asteroids spawning on the same plane as your spaceship? Are they remaining on the same plane, or are they drifting off course as the game continues? If not double check the transforms of these elements against the positions described in the tutorial. Please let me know what the results are and I can help further.
Your UnassignedReferenceException:
This variable screenDebris is a public variable that should appear as an assignable field in the Inspector when you select your GameManager. The error suggests you have not dragged the “Debris” Game Object from the Hierarchy onto this assignable field. However, as you are spawning asteroids during gameplay I assume you have indeed completed this step! Is your console set to “Clear on Play”?
Open the console window (either go to “Window” → “Console” or Command + Shift + C on the mac) And check that “Clear on Play” is selected to ensure the old logs are removed each time you enter play mode.
Restating the computer to quit:
As this tutorial is simply a “learning the basics of Unity’s user interface” We don’t get into creating user interface elements such as buttons and the like. If you create a standalone mac build and run the game it will keep running till you quit the application. Usually you should be able to move your cursor to the top of the screen to reveal the menu bar and navigate to “SpaceDebris” → “Quit” Alternaticaly, use the hot keys Command + q. However, depending on the settings used to build your application (“File” → “Build Settings” → “Player Settings”) you may not be able to access the menu bar, however, using the hot keys Command + q should still shut the application down regardless.
Please let me know how you get on with these suggestions… if you have any other difficulties, please do no hesitate to reach out.
Mark :]
Mark,
Thanks for the quick response. I went over what you suggested and here is what I came up with.
I’m not sure why it is different, but when I select the objects the in the prefab folder, the Ship is Z: 10, the Asteroid is Z: 12.5976, and the bullet (which I noticed is also on the wrong plane) is Z: 10.423. I ran the game, and the ship Z is still 10, but the asteroids are all at Z: 0, although visually, they are on different planes (although only slightly, and the rotation of some is Z: -180) and the bullet Z is 10 (Same as the ship, but visually it is off). The Sphere Collider component is in the Asteroid object, and the Z axis all says, 0. Yet this doesn’t explain why some asteroids get shot and some don’t (also, the ship runs into some asteroids and some it passes through). So I’ve done something wrong somewhere, but I’m not sure where. I’ve included a screenshot of looking down on the scene to show visually where everything is.
Looking at the sphere colliders also, the ship’s is set to Z: -0.72, the bullet is set to Z: 0, and the asteroid is Z: 0.89. I’ve verified the required inputs on the asteroid are the same, although the Z axis in Transform → Position is different. So I think there is an error there as well.
I’m rehashing the steps I think are were I made a mistake, but I’m still getting the same results. Maybe need to start from scratch.
I’m finding it difficult working on this on my little laptop, I’m going to try to export the project to my iMac, where I have more space to work, and verify everything again. Or I will build the game again tonight (japan time) and see if I can find the error.
Thanks again, I’ll keep working it.
Haole
Hi Again,
Thank you for the information.
Two nuggets of info to help us understand the values you are seeing in your game:
Keeping these things in mind… there are two things I think you should check to help you troubleshoot your game.
And one more thing I’m noticing, maybe this is just nothing, but when the asteroids generate, it looks to me like the sphere collider and does not generate where the asteroid is. Again, this doesn’t happen consistently, but I got a screenshot of one instance of Asteroid with what looks like the sphere collider (the green sphere?) and then the controls in two different spots, and not centered on the asteroid.
Hi Haole,
Thank you for persisting with this.
Please have a look at your Asteroid prefab in the Prefabs folder. Click the disclosure arrow beside it to reveal rockLP001. This is the Game Object that contains the asteroid’s mesh renderer, and as you will see, it has a transform or it’s own. Please make sure this transform is set to 0, 0, 0 for both the position and rotation and 1, 1, 1 for the scale. Any alteration to these values will offset the rendered asteroid from the Collider.
Let me know how you get on!
Mark
I had an issue with a part of the script when shooting a bullet, I wasn’t able to actually spam the button. The moment I pushed the spacebar button to shoot a projectile my spaceship was actually disappearing until the bullet flew off screen which was extremely confusing, not to mention the bullet never actually got destroyed. After scowering through the codes I found a fix by making a new variable in the bullet script and adding an update() function to replace the onBecameInvisible() function
using UnityEngine;
using System.Collections;
public class Bullet : MonoBehaviour {
// new variable to allow bullet on screen for specified time
private float timer = 1;
/**
* Remove Bullet when it leaves the screen
*/
void Update() {
timer -= Time.deltaTime;
if (timer <= 0) {
Destroy (gameObject);
}
}
// I decided to leave this here because Well it didn't make a difference to be honest
void OnBecameInvisible() {
Destroy (gameObject);
}
}
Hope this helps anyone who was having the same issue as me! 
I am a beginner and I had to set the depth of Camera to not less than 0 to see the Game preview correctly because the default value was set to -1.
This tutorial is more than six months old, so questions regarding it are no longer supported for the moment. We will update it as soon as possible. Thank you! :]