A Software Engineer’s Guide to Unity and AR/VR Development – Part 1

1) Resource.Load and GameObject.Instantiate during a runtime loop. Both of these are very expensive and will generate a ton of garbage.

2) Constantly Instantiating and Destroying GameObjects during runtime. This will create a ton of garbage on top of the expense of the Instantiate. The solution to this should be an object pool (http://catlikecoding.com/unity/tutorials/object-pools/ ). Realistically this is probably outside of the scope of this blog post, but maybe the author should have avoided Instantiate in an introductory example.

3) GameObject.Find to locate a fixed game object in the scene. This should be replaced with an object reference (references can be connected in the editor), or if that doesn't work for whatever reason use Find once in Start or Awake and store a reference to the object are a member variable. Unity recommends to not use it every frame in it's documentation (https://docs.unity3d.com/ScriptReference/GameObject.Find.htm...)

4) Debug.Log can be useful in a pinch, but doing it in Update or other frequently called method can cause performance problems, also printf debugging has never been great. Visual Studio debugger support is really good in Unity, use that.

This code is ok if you don't care at all about performance, but in a VR or AR app you can quickly add milliseconds frame time and make yourself sick writing relatively simple code in this style.

I might go so far as to say it's the ActiveRecord to Unity-as-Rails for AR/VR, although the analogy is really flawed.

While I like your overall approach (a true, comprehensive intro to Unity), I would have liked to see more about, I guess I'd call it, the philosophy of putting code into Unity, covering (specifically and, IMHO, most importantly) the type of component system they're using, and type of event system they're using. The equivalent of describing a new language in terms of which features from the language grab-bag the authors decided to use.

PS - Pluuuuug, because dealing with JSON/YAML in C# suuuuucked: https://github.com/narfanator/maptionary

- Boo support is all but dropped, so avoid going with that.

- The JavaScript variant is not exactly what is in a browser.

- For C# MonoBehaviours, the class name must match the file name (without extension) in order for Unity Editor to see it. Namespaces are both supported and not displayed when adding a component.

- The Editor identifies file relationships by the GUID assigned in "meta files" if "Visable Meta Files" is chosen in the "Version Control" entry in the project settings. All files imported will then have another created with a suffix of ".meta".

- Selecting an "Asset Serialization" mode of "Force Text" will cause Unity to use YAML for things such as scenes, prefabs, meta files, etc. This can make using Git much nicer as well as enable use of text processing tools (such as grep or ack).

- When importing assets from the Asset Store, always review what files the package wants to import! Many will ship resources such as Standard Assets which can be outdated and/or cause conflicts.

- The built-in package management will only update or add files from a package. This many times leaves stale files lying around which can cause problems.

EDIT: If using text (YAML) serialization and Git, trying to merge conflicts in scenes (.unity) or prefabs (.prefab) will almost certainly end badly. Better to coordinate changes between people through communication, doing a "use mine or use theirs" conflict resolution strategy when people step on each other's work.

EDIT-2: Here are three utility assets which I have found to be invaluable (all are free):

- Vexe Framework: https://github.com/vexe/VFW

- LINQ to GameObject: https://www.assetstore.unity3d.com/en/#!/content/24256

- Unity Test Tools: https://www.assetstore.unity3d.com/en/#!/content/13802

Even Unity's own official tutorials are all in video form.

https://www.amazon.com/dp/B014DIV1IO/ref=dp-kindle-redirect?...

I've been using Unity for the last 3 years and that book covers a good chunk of what it takes to make a performant game with it. Good books on Unity are hard to come by. Also highly recommend this book if you are just learning about game and simulation engines:

https://www.amazon.com/Engine-Architecture-Second-Jason-Greg...

Day job is Java HFT FinTech, so I wanted a short bridging course.

There are many blogs about it, but if you really want to learn fast yet thoroughly I would recommend an online video course.

I recently did Ben Tristem's Unity Course - https://www.udemy.com/unitycourse/ which is excellent and shows you all the tips and tricks of the trade. Wishlist the course and often there are massive discounts

Some non-obvious things:

- Animation - Prefabs - AudioSources - Colliders - Scenes and Scene Management - localPosition - Quaternion.EurlerAngles - Raycast - finding named objects in the scene - relation between GameObjects and Transforms