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c#unity-game-engineoptimizationconditional-statements
Edward Severinsen
Edward Severinsen

Reputation: 703

Ways to optimize conditional?

I'm making a game in Unity3D and am currently creating an AI for the enemy. The enemy needs to walk around and search for the player without running into walls.

The enemy always moves forward on it's local z-axis until it encounters an obstacle or the ray made by Raycast hits an object. When the Raycast hits an object that is part of the environment it then Raycast in all 7 directions diagonally, side-to-side and front-to-back to check for more obstacles near it as shown in this image.

Raycast Example

The path it takes is then determined by whether or not these rays hit another object and go in the direction in which a ray didn't hit anything and that is the most optimal direction.

By most optimal I mean in the order:

  1. fl OR fr
  2. l OR r
  3. bl OR br
  4. b

I need to decide based on this data which direction to turn. If in a case where say fl and fr are both true then I would randomly decide between the two directions.

I want to optimize this process so I don't have to use multiple if-statements. I had thought of using bitmasking techniques since there are 8 directions, if you include forward, and each bit could represent a direction.

Any ideas, constructive criticism, etc is welcome. Thanks for your time.

Upvotes: 1

Views: 194

Answers (2)

zambari
zambari

Reputation: 5035

Do not optimize pre-maturely, it is the root of all evil, as some say. This would be a perfect example.

The reason we code in C# and not in assembly (or even C) is not performance, it's readability. While it may be possible to make your code run a tiny bit faster, the results may not even be measurable. an IF branch here is still pretty tiny, and I would strongly advice against replacing it with anything else - you will loose a lot of readability, while not gaining much, if any at all performance. Bitmasking techniques start to become effective when you deal with thousands of objects (i.e. Entity), but if your if branch fits on a couple of pages, I would not touch it unless I'd find it to be a major drag by measuring it in the profiler. If you are not sure what you are doing its not that hard to make your code run slower. The priority is to make the code readable (definitely in your case as you won't be running it in a tight loop), and easy to modify. In some cases it's better to unroll the code into a more verbose if branch than to pack it into some bizarre loop - remember a loop is also an instruction.

Upvotes: 1

Dan Ferguson
Dan Ferguson

Reputation: 31

G,day!

I have been reading a lot lately about the new path-finding system in Unity 2018. I was wondering if you had checked it out yet?

If you wanted to create it from scratch, mad props to you - however, I would be following the documentation (on the Unity website) to create an Update script on the enemy GameObject that would find the shortest path to the player GameObject's transform position, making sure to adjust for obstacles.

Have a browse around on YouTube as well - there are heaps of great tutorials.

Otherwise - if you were looking to do it on your own, the way that I would personally do it (which probably won't be the most optimal) will be though at each frame, scanning for potential paths and then finding the shortest one and acting upon it by moving the enemy based on a predetermined speed * time.deltaTime. A great visualization of the system can be found on Devon Crawford's website (link below).

Unity Documentation Link: https://docs.unity3d.com/Manual/Navigation.html Devon Crawford's Website: http://www.devoncrawford.io/software/pathfinding

Upvotes: 1

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