Screen wipe getting skipped after level load

Unity Engine
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1

So I wrote some code to make a custom screen wipe every time a level loads.
The problem is that when I wipe in after a new scene loads, the whole effect usually gets skipped or only appears for a couple frames, when it is supposed to play for a full second.

Okay, this is probably happening because the code that animates the wipe is based on a simple counter that adds unscaled delta time, and after loading a scene that delta time is probably pretty high since no code was executed during the scene load.

So that’s a simple fix, right? Just add an extra bool so that the first frame gets ignored, and then the second frame is when the wipe counter actually starts.

Except that it still gives me this problem. So I added a second bool so that it waits two frames. Annoying, but fine, I can deal with that.

But no! Even after that I still face a crap-shoot where sometimes I get this wipe that disappears in the blink of an eye, and sometimes it doesn’t even appear at all!

I’m just using the default load scene function from the scene manager; no asynch load because my scenes aren’t big enough to be worth any kind of loading screen or animation.
But what is going on that I still randomly get multiple frame drops when the scene loads?

I don’t believe it is an issue with too much going on with scripts initializing, because if I load the current scene again (which resets all the scripts but doesn’t load anything new) I only get a nearly-imperceptible drop in frames, and the animation still proceeds as normal.
(though that said, I do wonder if there is a simple way to make sure all starting scripts have run their wake functions before running the wipe effect.)

Any ideas what might be causing this?

2

That does not sound like debugging to me. :slight_smile:

Whenever you need more information about what your program is doing as well as how and where it is deviating from your expectations, that means it is…

Time to start debugging!

By debugging you can find out exactly what your program is doing so you can fix it.

Here is how you can begin your exciting new debugging adventures:

You must find a way to get the information you need in order to reason about what the problem is.

Once you understand what the problem is, you may begin to reason about a solution to the problem.

What is often happening in these cases is one of the following:

  • the code you think is executing is not actually executing at all
  • the code is executing far EARLIER or LATER than you think
  • the code is executing far LESS OFTEN than you think
  • the code is executing far MORE OFTEN than you think
  • the code is executing on another GameObject than you think it is
  • you’re getting an error or warning and you haven’t noticed it in the console window

To help gain more insight into your problem, I recommend liberally sprinkling Debug.Log() statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

  • is this code even running? which parts are running? how often does it run? what order does it run in?
  • what are the names of the GameObjects or Components involved?
  • what are the values of the variables involved? Are they initialized? Are the values reasonable?
  • are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as Debug.Log("Problem!",this);

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

Visit Google for how to see console output from builds. If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer for iOS: https://discussions.unity.com/t/700551 or this answer for Android: https://discussions.unity.com/t/699654

If you are working in VR, it might be useful to make your on onscreen log output, or integrate one from the asset store, so you can see what is happening as you operate your software.

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

If your problem is with OnCollision-type functions, print the name of what is passed in!

Here’s an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

https://discussions.unity.com/t/839300/3

If you are looking for how to attach an actual debugger to Unity: https://docs.unity3d.com/2021.1/Documentation/Manual/ManagedCodeDebugging.html

“When in doubt, print it out!™” - Kurt Dekker (and many others)

Note: the print() function is an alias for Debug.Log() provided by the MonoBehaviour class.

If you learn more by debugging and there is some specific thing that still seems mysterious…

How to report your problem productively in the Unity3D forums:

http://plbm.com/?p=220

This is the bare minimum of information to report:

  • what you want
  • what you tried
  • what you expected to happen
  • what actually happened, log output, variable values, and especially any errors you see
  • links to actual Unity3D documentation you used to cross-check your work (CRITICAL!!!)

The purpose of YOU providing links is to make our job easier, while simultaneously showing us that you actually put effort into the process. If you haven’t put effort into finding the documentation, why should we bother putting effort into replying?

If you post a code snippet, ALWAYS USE CODE TAGS:

How to use code tags: https://discussions.unity.com/t/481379

- Do not TALK about code without posting it.

  • Do NOT post unformatted code.
  • Do NOT retype code. Use copy/paste properly using code tags.
  • Do NOT post screenshots of code.
  • Do NOT post photographs of code.
  • Do NOT attach entire scripts to your post.
  • ONLY post the relevant code, and then refer to it in your discussion.
3

Is the screen wipe effect in the previous scene that’s getting unloaded?

4

No, the screen wipe is handled by my GameManager object, which is set to not destroy on load. So the effect and the graphics it uses are never unloaded.

5

Well does just sound like a thorough debugging is needed. Even the most strange things usually have a straight forward root problem.

Debugging the frame count and the timer seems like a good starting point.

What stands out to me is this, though:

The Unity documentation recommends using the async scene loading methods even under normal circumstances. There’s a lot of steps to loading even a small scene, and this is best spaced out over a number of frames; what the async methods do.

Also note that scene loading in the editor is notably slower than in a build for editor reasons.