The blueprint math expressions node feedback/bugs

Development Programming & Scripting Blueprint
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1

The blueprint math expressions node seems bugged on the latest 4.2 build.

In 4.1.1 you can add variables and choose different types like vector’s, but currently in 4.2 that stuff does not appear to be working. As the drop down menu for type selection does not change the type it remains a float.

Both versions have a rename param issue where changing the variables name does not update the expression string or at least keep a visible mapping between a friendly variable name and the expression.

Lastly the math expression’s node’s name and expression string are mapped to the same string, which prevents friendly naming of complex expressions.

2

Hi Goldfinger,

Thanks for the feedback!

I’ll look into the issue with the type changing, and log a bug for the variable rename issue (this is something we hadn’t thought of).

As for the expression and name being coupled: you could always add a comment to the node providing the friendly “name” that you want.

Keep on banging on it and let me know if you come up with anything else. If you have github access, we recently fixed up the expression node even more and pulled it out of experimental. You might want to try it out in main and see if some of your issues go away.

Thanks!

3

Some extra things I found since,

The reordering of the variables in the list to make more logical sense breaks all the connections. Creating duplicate errors and corrupts the graph requiring you to delete everything in that graph section and start again.

Also the auto save warning popup message takes focus away from the input fields while typing which is annoying.

I will test a master branch build as 4.1.1 has the above problems also but the vector/type params changing works in the current 4.1 release but it starts get screwy if you rename the variables which clearly is not supported.

love the math expression node just needs to be less fragile most of the details panel features cause problems.

4

currently unable to build the master branch due to physX errors would appear required packages need a new physX library

5

Hi Goldfinger,

There was recently an API change in PhysX which is what you’re currently hitting. Unfortunately we only update the libs when we get a screenshot so you’ll need to wait for that, or roll back to the last screenshot.

Sorry for the trouble

6

Hi Ori

yeah was trying to verify Mikes idea to try main see if any of the bugs have been fixed.

can someone make sure the bug are atleast in the tracker

  1. Reordering types in the math expression variable list causing graph corruption

  2. The types not being changeable 4.2+ it worked in 4.1

  3. auto save steals focus in the editor

  4. Variable renaming does not up date the expression.

Thanks

7

Hello Goldfinger,

I was hoping you could explain in further detail about your #1 issue, and the steps you take to reproduce the issue please.

As for issues #2 through 4, there are open bug reports in our tracker for them now!

Thank you,

~Sam

8

Issue 1. is if you have an expression with multiple inputs the order first appears based on the order in the equation if you try to use the up and down arrow buttons in the node details panel to reorder those variables to make the order more logical

the result from clicking those buttons is the graph that makes hidden duplicates of the connection wires and you started getting errors saying you can only have one wire per connector something to that effect.

the only way to resolve this error from this point is delete the graph and start again deleting the math expression and all wires connecting to it and the nodes as the duplicate wire errors remain if you delete the wires you can see depending on how many times you reorder I guess the more duplicate wire links in the backing blueprint graph data are being generated.

Used weight average as a quick test ((v * (N - 1)) + w) / N order appears v N w if you reorder example v w N top to bottom should see graph errors

9

I just resolved issue #2 there with CL 2102010.

Here’s a link to the commit: https://github.com/EpicGames/UnrealEngine/commit/d8b88372ed637509d8aa3abc2ff0c335dd34b807

10

Before the change I mentioned above (to fix issue 2), I couldn’t reorder the variable at all (just like you couldn’t change the variable type), but after that fix the reordering seems to work fine (tried it out with the equation that you specified here). So looks like issue 1 was fixed by the same change: https://github.com/EpicGames/UnrealEngine/commit/d8b88372ed637509d8aa3abc2ff0c335dd34b807