You Are Using Update Loop Wrong | Practical Unity Tutorials

you have an idea for this game you watch some  tutorials added some enemies created a player character you have the latest graphics card  for the Knight DTI but for some reason your game runs slowly at only 20 FPS then you start  having these self-doubting thoughts because you just realized that a full fledged game like  Red Dead Redemption 2 runs at steady 60fps on a microwave while your empty project that  contains only placeholder white cubes burns more electricity than a Bitcoin Farm if you 

can relate to this then watch this video till the end and I will tell you exactly what you  are doing wrong it's the same reason why all those Early Access games on Steam are always  laggy it's because their developers didn't subscribe to my channel and if you also didn't  subscribe please do it now let's begin our video you are already probably familiar with an update  loop it's one of those first things that you will ever learn in unity an update Loop is only  executed once per frame but what

does that mean if your game is running at 60 FPS that means that  an update Loop will execute exactly 60 times if you tell Unity to print hello world in an update  Loop it will print it 60 times every second so this is only a simplified way of how it works I  assume that many of you have used an update look before but what if you are unaware that you are  doing something wrong in that case I'm going to guide you through some points of what you could be  doing wrong and provide you with some alt

ernatives recently A friend of mine reached out to me to  help him with his code he showed me this class of enemy where he checks whether enemy is dead or not  if it's true then it proceeds to destroy the enemy game object if it's not true then it returns out  of the method the only problem with his approach is that he is doing all of this in an update Loop  so that means that his CPU will keep checking the enemy State forever is this really necessary in  a real case scenario you would want to k

now the enemy state only when you need to know it let  me explain since his game is running at 60 FPS that means that it will check enemy State 60  times every second so your computer is doing all these extra calls that the player does not  benefit from a player does not need to know if enemy is dead or not every frame every second on  top of that it is wasting CPU resources that could be allocated somewhere else in other words this  is what we call game optimization you have to be very smart wi

th how you did distribute tasks for  your computer but remember that my friend had 10 enemies which means that his CPU had to check  for 10 enemies and not for one for 10 enemies that is 60 times 10 equals 600 checks every second  that's still okay if you are running on a high-end PC but let's say that you are making a game for  Android phones and it needs to run on a low end Android phones that could drastically affect its  performance and even though your high-end PC can eat all of this it doe

sn't mean that you should  keep doing this bad practice or on a job interview an interviewer might dismiss you immediately if he  notices that you are doing this beginner's mistake also my friend had this code where he finds the  distance between the player and the enemy which was like 5 lines of code of course I'm just making  this up for this simplification now let's do the math 5 times 60 equals 300 calls and times 10  enemies which is 3 000 calls every second let's not forget from this other

example those 600 calls  which now adds up to 3600 calls every second and this is one of the most common mistakes that every  beginner does everything that they add to the game they put it inside an update Loop and not just  them but also in these other YouTube tutorials you can see it too that's exactly why you cannot  escape the tutorial hell is because you were never taught the best practices 3600 cores might not be  much but things can add up easily and now it could become 80 000 calls and

your game could experience  spikes which is something you never want to happen in an example where we check whether enemy is dead  or not instead we could do checks only when it's hit by a projector and now when projector Collies  with the Enemy that's the only time where we're going to check the enemy state so we don't need  to check enemy stay constantly like we did before at Max let's say we can only shoot 15 projectiles  in one second that will make a worst case scenario 15 and that will red

uce calls from 600 to 15 and  our best case scenario is zero or no calls at all because our enemy is not shooting and if player  does the shooting and misses all the enemies that's still going to be zero cause because  no enemy was collided with the projectile if you remember calls are only made when projectile  successfully collides with the Enemy so we could make our projectiles disable self on collision  and that will make our CPU to only make calls on a single enemy but in my friend's exampl

e it  made calls on every single enemy in the scene even those that are not in the player's view now  imagine a large game as a Grand Theft Auto and if Rockstar developers checked if some random NPC  at the other end of the map was alive and imagine if they did that for the every NPC in the game  and do you know how many NPCs are there in GTA probably thousands do the math and see yourself  how many calls are there of course this is just an exaggerated example of our problem Rockstar  developers

will never have some random NPC at the other end of the map loaded in the memory  normally in games like these an NPC would be loaded only when the player is close to him  and this is what we call object pooling and we will discuss that in the future videos never  call get component in an update Loop ever it's a relatively expensive operation it searches  through all game objects in the scene hierarchy until it finds the one that you need and it's  another good thing to do what you want to do i

nstead is to Cache the reference in the awake or  start or just drag the reference in the inspector another thing I want to add is to build a  habit of using core routines quarantines are way easier to handle than having the same  code running in an update loop it's way easier to stop according when it finishes while an  update Loop can only be disabled when the game object is disabled but what if you can't  disable that game object then that update will keep running I will make tutorial on core

  routines so if you didn't subscribe please do it this is a very common beginner mistake and you are  probably unaware that you are doing it never leave an update Loop empty ever because Unity will  call that update Loop internally even though it's empty and it will make unnecessary calls is  the best practice to remove awake unenable start update fixed update all those methods if they  are empty I used to do this as well don't go for an update Loop immediately 99 the script  that you are writi

ng probably can be written outside of an update Loop if you are dealing  with the UI stuff like players Health enemies held remaining bullets anything that needs to  change constantly all of that can be updated in a single frame don't even think of an update  Loop what I recommend instead is to go for an event-driven Solutions and what do I mean by  event driven as a beginner I used to grab a player and grabs its Health property and then I  would update that Health constantly in an update Loop a

nd so the CPU would tell the player hey this  is your health even when the hell didn't change so it's very important to make calls only when  something actually changed and not every frame here's one more optimization tip that I will  share with you I have this skeletons AR game that's of course an augmented reality game in  order for a player to be able to play the game he has to place this turret on the ground so for  my phone to be able to place the turret on the ground he has to run this Ray

from the phone in  direction of the ground and the only way to do this it has to be run in an update Loop raycasts  are very expensive so you don't want them to run when not used so when I actually place the turret  on the ground I disable the game object that runs the raycast so the CPU is not calculating the  distance between the phone and the ground when the player is playing the game because it doesn't  benefit from knowing that information and also the phone battery will last longer becaus

e of that  in conclusion always disable game objects that run an update Loop if possible if you are looking  for free unity and programming tips I built the community that you can join I will provide  the link in the description it's still a new community that I'm looking to grow and I'm always  there so if you have any questions feel free to ask me this is it guys if this video was helpful  Please Subscribe and see you in the next video