I'm still pretty new to scripting in Unity3D, and I'm following along with a tutorial that uses GUI.Button() to draw a button on the screen.
I am intrigued by how this function works. Looking through the documentation, the proper use of GUI.Button is to invoke the function in an if statement and put the code to be called when the button is pushed within the if statement's block.
What I want to know is, how does Unity3D "magically" delay the code in the if statement until after the button is clicked? If it was being passed in as a callback function or something, then I could understand what was going on. Perhaps Unity is using continuations under the hood to delay the execution of the code, but then I feel like it would cause code after the if statement to be executed multiple times. I just like to understand how my code is working, and this particular function continues to remain "magical" to me.
I don't know if it's the right term, but I usually refer to such system as immediate mode GUI.
how does Unity3D "magically" delay the code in the if statement until
after the button is clicked?
GUI.Button simply returns true if a click event happened inside the button bounds during last frame. Basically calling that function you are polling: every frame for every button asking the engine if an event which regards that button (screen area) is happened.
If it was being passed in as a callback function or something, then I
could understand what was going on
You are probably used to an MVC like pattern, where you pass a controller delegate that's called when an UI event is raised from the view. This is something really different.
Perhaps Unity is using continuations under the hood to delay the
execution of the code, but then I feel like it would cause code after
the if statement to be executed multiple times.
No. The function simply returns immediately and return true only if an event happened. If returns false the code after the if won't be executed at all.
Side notes:
That kind of system is hard to maintain, especially for complex structured GUI.
It has really serious performance implications (memory allocation, 1 drawcall for UI element)
Unless you are writing an editor extension or custom inspector code, I'd stay away from it. If you want to build a menu implement your own system or use an external plugin (there are several good ones NGUI, EZGUI,..).
Unity has already announced a new integrated UI System, it should be released soon.
Good question. The unity3d gui goes through several event phases, or in the documentation
Events correspond to user input (key presses, mouse actions), or are UnityGUI layout or rendering events.
For each event OnGUI is called in the scripts; so OnGUI is potentially called multiple times per frame. Event.current corresponds to "current" event inside OnGUI call."
In OnGUI you can find out which event is currently happening with >Event.current
The following events are processed link:
Types of UnityGUI input and processing events.
-MouseDown
-MouseUp,mouse button was released
-MouseMove,Mouse was moved (editor views only)
-MouseDrag,Mouse was dragged
-KeyDown, A keyboard key was pressed
-KeyUp A keyboard key was released.
-ScrollWheel The scroll wheel was moved.
-Repaint A repaint event. One is sent every frame.
-Layout A layout event.
-DragUpdated Editor only: drag & drop operation updated.
-DragPerform Editor only: drag & drop operation performed.
-DragExited Editor only: drag & drop operation exited.
-Ignore Event should be ignored.
-Used Already processed event.
-ValidateCommand Validates a special command (e.g. copy & paste).
-ExecuteCommand Execute a special command (eg. copy & paste).
-ContextClick User has right-clicked (or control-clicked on the mac).
Unity GUI has much improved lately and is quite usefull if you want to handle things programmatically. If you want to handle things visually, i recommend looking at the plugins heisenbug refers to.
If you decide to use unity gui, i recommend using only one object with ongui, and let this object handle all your gui.
Related
I try to handle some events during animations, but everywhere I look, every tutorial have access to AnimatorEvent Inspector like this:
A nice simple field, where you can select a function, I want this!
But instead of this, I always getting this sick 5 fields view, and don't have any idea how to handle animation event in this case!
I tried to create function test() with debug log, but it didn't work anyway. Why I can't get access to this simple window where I can choose an function?
You will need to add this animation into a State in Animator Controller (via Animator Window).
In the object which contains Animator component, attach your script component to it.
Open the Animation window, select the object above, you will see a dropdown of animations (top left) which Animator Controller of this object contains. Choose and add event to the animation you want to.
Select the event in Animation Window, in the Inspector, you should see the dropdown of public functions of your script component attached above.
Answer by Aluminium18
Sometimes it doesn't work even if you do all things according to tutorials or advices in internet. I often leave Unity editor launched for a long time without any interactions with it. After several gibernations and several days it can get buggy - various errors appear, you can't see some functions from scripts and so on. So, just reloading the Unity editor solves many of such issues for me. And it continues to happen so for several years no matter what Unity version you have. I tried versions from 2019.x.x to 2022.x.x - all this time Unity behaves itself the same.
I am facing issue with callbacks. I have 3 drop downs, one scattermap , one table and one slider on the screen and they all need to work in tandem and i have 5 call backs. When i execute the application all my callbacks associated with these controls execute in random order. After that when i click on scattermap it may or may not work. Say we assume it worked. Then i can navigate all around without any hassle. Then if i execute the application then click on the scattermap then as i mentioned it may or may not work. Say suppose it didn't work this time. If so is the case it will not work at all no matter what i do and simulaneously one specific dropdown also becomes dysfunctional. However if click any of the other two drop downs then evrything will start functioning as normal.
I have digged really deep into this and figured out that this has nothing to do with my code. The underlying issue is that when the click doesn't work the reason the reason behind that is the callback isn't getting triggered. I found out this by applying some debugging techniques and i am 100% sure the callback is not firing. Can anyone help me resolve/understand this please.
I want to use an editor to display a log from a program, I just need a very basic text field:
With a vertical scrollbar
With a contextual menu for copy/paste
Prevent the user from changing the text
In order to activate the copy/paste menu, I use the class racket:text% from framework rather than the basic one.
How to prevent the user from changing the text?
I read the documentation, as far as I understand the closest thing I found is lock method:
https://docs.racket-lang.org/gui/editor___.html?q=lock#%28meth._%28%28%28lib._mred%2Fmain..rkt%29._editor~3c~25~3e%29._lock%29%29
But it is not convenient, as it also prevent my program to write the data.
I also find get-read-write? but cannot find set-read-write.
Use the lock method, and just unlock the editor around any modifications that you want to do. You may find it useful to write a call-with-unlock helper function or with-unlock macro.
If you do your updates from the eventspace's handler thread (and you probably should; use queue-callback if they originate from another thread), then as long as you re-lock the editor at the end of an update, the user will never be able to interact with the unlocked editor.
I am working on a large (>30k lines) event-driven app. I have a sequence of inputs that produces a bug. What I want to do is to break as soon as the final input enters my code.
Is there a general way to do that?
I understand that for any specific sequence of inputs, I can find out where that last input is going to enter my code, then set a breakpoint there. What I would like to do is take out the step of "find out where that last input enters my code." In other words, I am running the app in the simulator, and I want to set a flag somewhere that says "break the next time you are going to enter non-system Objective C code." Then I send the event that causes the problem.
I understand what you are asking, but have you tried using an Exception Breakpoint? This will basically act like an auto-inserted breakpoint on the piece of code that throws the exception. If that doesn't work for you, try a symbolic breakpoint
If you want to intercept UI events, you can try subclassing UIWindow and overriding its sendEvent: method, then setting this class as the class of the UIWindow object in your main XIB file. sendEvent: will be called each time the user generates a touch event. Unfortunately, at this point you cannot yet know which UI object will finally consume the event (read: which event handler code will be ultimately called) since that depends on the actual state of the responder chain. But anyway, you can use this method to inject events into the system.
In our project, we're using gtkmm and we have several classes that extend Gtk::Window in order to display our graphical interface.
I now found out what call produces the behaviour (described in the previous revision. The question now slightly changed.)
We're displaying one window, works like a charm.
Then, we have a window which displays various status messages. Let's call it MessageWindow. It has a method setMessage(Glib::ustring msg) which simply calls a label's set_text().
After some processing, we hide this window again and we now show a toolbar. Just yet another simple window, nothing crazy.
For all windows applies: The main thread calls show() on the window and creates a new thread which calls Gtk::Main::run() (without argument).
That's how it should be, until now.
The problem starts here: The main thread now wants to call MessageWindow::setMessage("any string"). a) if I call this method, the message window reacts completely correctly. But afterwards, the toolbar-window is displayed empty. b) if I don't call it, the message window doesn't change the label (which is absolutely clear), and the toolbar window is displayed as it should.
Seems like the windows are messing up each other.
Now the question:
If my gui-thread is blocking in Gtk::Main::run(), how can I now change the text of a label?
We're using gtkmm-2.4 (and no, we cannot upgrade)
Any help is appreciated.
Wow! That's complicated...
First: you should not manipulate windows from several threads. That is you should have just one GUI thread that does all the GUI work, and let the other threads communicate with it.
It is theoretically possible to make it work (in Linux; in Windows it is impossible) but it is more trouble than it is worth.
Second: the line Gtk::Main main(argc, argv) is not a call, it is an object declaration. The object main should live for the duration of the program, so if you use it in a object constructor, as soon as you return from it, the object will be destroyed! Just put it at the top of the main function and forget about it.
UPDATE: My usual approach here is to create a pipe, a g_io_channel to read, and write bytes on the other end.
Other option, although I didn't test it is to call get the GMainContext of the main thread and then g_idle_source_new() and attach that source to the main context with g_source_attach(). If you try this one and it works, please post your result here!