Best way to check if an object is within the visible range of the play area?

You can get the coord of border

X Left Frame, etc.

Then you can compare the object coord to this, by manually making four compare conditions

That's right, but instead of using the object's X position, you may want to test the edges of the object - ie. "X coordinate of left edge", "Y coordinate of top edge" etc.
That way, it'll work if any part of the object's bounding box is on screen, rather than just the hotspot (it's a small detail that may or may not be significant, but with larger objects especially, it makes sense).

There's no condition to compare those directly though, so you'll need to use the object's "Compare expression to a value" condition (do NOT use "Compare two general values" if there are going to be multiple instances of the object).

Also, note that if you just say "add 1 to a counter", it will add 1 if ANY instance is within view, but will never add more than 1, even if many instances are within view.
Instead, set the counter to "Number of selected objects".

eg.
* Enemy: X Right( "Enemy" ) >= X Left Frame
+ Enemy: X Left( "Enemy" ) <= X Right Frame
+ Enemy: Y Bottom( "Enemy" ) >= Y Top Frame
+ Enemy: Y Top( "Enemy" ) <= Y Bottom Frame
Counter : Set Counter to NSelectedObjects( "Enemy" )

another way to do it: create an invisible asset the size of the "screen", position it at 0.0 and uncheck "follow the scene" then test if "the object is in collision with the asset"
at the same time I do "if object is not in collision": make invisible (speeds up the runtime enormously)

on android, i can have 40 fps without this technic and 60 using it! (with a lot of sprites)

Quote from MuddyMole

That's right, but instead of using the object's X position, you may want to test the edges of the object - ie. "X coordinate of left edge", "Y coordinate of top edge" etc.
That way, it'll work if any part of the object's bounding box is on screen, rather than just the hotspot (it's a small detail that may or may not be significant, but with larger objects especially, it makes sense).

There's no condition to compare those directly though, so you'll need to use the object's "Compare expression to a value" condition (do NOT use "Compare two general values" if there are going to be multiple instances of the object).

Also, note that if you just say "add 1 to a counter", it will add 1 if ANY instance is within view, but will never add more than 1, even if many instances are within view.
Instead, set the counter to "Number of selected objects".

eg.
* Enemy: X Right( "Enemy" ) >= X Left Frame
+ Enemy: X Left( "Enemy" ) <= X Right Frame
+ Enemy: Y Bottom( "Enemy" ) >= Y Top Frame
+ Enemy: Y Top( "Enemy" ) <= Y Bottom Frame
Counter : Set Counter to NSelectedObjects( "Enemy" )

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Outcast  MuddyMole Already had the best answer to this, basically compare ranges, it's the fastest and cleanest way honestly
As you are dealing with rectangle ranges, compare ranges like MuddyMole showed above (there is also a range expression for that) or in terms of circles, compare distances, other than that, I wouldn't really recommend checking for collisions, as it's not the most ideal way, not the cleanest and the slowest out of all methods (also the zone objects have to be on the same layer as the objects that gonna be inside the zone, and the only way to check for collisions with objects on other layers is to move them to that layer, check for overlap, then move back to the og layer)

The collisions method should only be used for ranges that are not necessarily rectangles or circles..

In terms of zoning objects, DON'T resize the object manually in the frame editor, rather, scale in events, as that would be a texture for each unique zone, so a 512x512 zone, would be a 512x512, which is not good for memory
But in case you want to the convenience of just resizing objects in the frame editor, you can use Active System Box objects that act as spawners to spawn the real zone objects that are just normal Actives scaled to the size of the Active System Object that spawned them, then after the spawn procedure is done, destroy the active system boxes..
But why do that when you can just use the Active System Objects as the zones outright instead of as spawners? they are slower than Actives, in fact, it's much slower than Actives especially on other runtimes, so I only use them as spawners of something to there convenience of being able to resize them in the frame editor without affecting memory usage (and also the cool ways I can customize there appearance, they can be used s great visualizers)

Here is a very simple example I made before about limiting camera movement, it uses the zones method I just explained with the with ranging method MuddyMole explained, should be fairly simple to understand:

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Note: If you want to check with multiple "players" (like enemies or something) you can slightly modify tthe way it checks for zones by running a foreach loop on the enemies then checking for that loop in the zone comparison event, like this:
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If you don't need to detect the exact moment that an object leaves the screen with absolute pixel-perfect precision, then there's a simpler way to do this. The following example will add 1 to an altVal of all splash objects that are on the visible part of the game area (or at least are close to it).

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That's the method I use, and it works well. The -700 creates a margin around the outside of the screen so that objects must be beyond this margin before they are considered out of screen. That ensures that any objects 700x700px and smaller will be entirely out of sight (and not merely partly off-screen) before they are considered out of the visible area. Set the number to the maximum dimension of the objects you'll be testing, as a negative number. For example, if the largest object you'll be testing is 32x64px, then set the number to something like -65.

The condition to use is this one:

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...and you must negate it:

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Quote from Outcast

I am curious how you made those even lines? Like ----------Movement----------. I have tried but I just get an error when trying to insert a - sign

I imagine they're a special unicode character rather than the normal minus sign on the keyboard

The top left symbol in the first table that appears in Please login to see this link. on undicode box/line characters worked for me where the standard minus wouldnt

Or you can copy/paste it from here: "─"

He's using dash characters instead of the minus symbol (that's also why the characters line up perfectly, with no gap in between).
You're allowed to use a short "En dash" –
...or you can use a longer "Em dash" —
See: Please login to see this link.

Edit: Haha, never mind, too slow...

Yes, there are a bunch of different dashes of different lengths available. The one I use is the longest, and is called the "Three-Em Dash" (unicode U+2E3B): ⸻

I use different characters and symbols a lot, to keep my code as organised and readable as possible. Though it's important to make the process of using these unusual symbols as quick and easy as possible so that they can aid your workflow rather than impede it.

I've changed the firmware on my QMK keyboard to turn the CapsLock key into a special modifier key that can be used to output certain special characters. So I can press caps+minus for ⸻, caps+period for ……………, caps+space for an extra long space [ ] or caps+shift+space for an extra short space [ ]. Or caps+aeclonszx for the Polish letters ąęćłóńśżź. Also caps+tab/shift/tilde to turn the current selection into UPPER CASE / lower case / Title Case. (I can also press caps+F1 for the original CapsLock functionality).

I can also output certain symbols that I use in altVal/string/flag names to denote what type of variable they are, which I find improves the readability of my code:

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I've actually found appropriate keycaps for some of these, as shown above. For others I use my Stream Deck. For the rest, I use a clipboard manager called PhraseExpress (Ditto would work too):

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Anyway, there are loads of useful characters you can use. I recommend using Character Map UWP from the Windows Store to find them - it's less laborious to use than the native Windows Character Map utility. Look through the fonts Segoe UI, Segoe Emoji, Segoe Historic, Segoe UI Symbol, Segoe MDL2 Assets.

Some characters don't work in Fusion, or become illegibly small. But over the years I've built up a text file with categorised symbols that are confirmed to work well in Fusion (in group names, comments, altVal and object names, though some temporarily display as squares in the expression editor). I'll attach the text file below.

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