I’m not entirely sure where this issue is stemming from, but I hope the following screenshots highlight the problem I’m having. I have re-created a material network that I created in UE3 to UE4, but there are apparently some math differences in the way the panner nodes now work, which is causing it to break/render incorrectly.
The idea is to add a second layer of more interesting UV distortion, this is the material network in UE3, all the nodes are commented with their values and ‘live preview’ is switched on, so you can see exactly what’s happening at each node:
I then re-created this network in UE4, but as you can see, the panner nodes offer quite a different preview, setting negative panning speeds in the panners actually seems to cause them to preview completely incorrectly, and this is having an effect on the resulting math that follows, the difference between the UE3 and UE4 material is quite substantial and broken.
A more obvious example is probably here, where I’m using another layer of distortion on top of the original, again, the UE3 preview shows the correct result, whereas the UE4 preview is completely blacked out on some nodes due to the negative values in the panners. This is causing some strange tiling on my resulting material.
I’m not really sure how to explain the issue further, but you can see the difference in the nodes themselves, and this is causing an issue with my final material.
Hi James,
I’ve been looking into your issue as well. Would it be possible to provide an example image of your final result in-game from UE3 vs. UE4 so that we may see the difference?
Thanks!
-W
Hey guys, hopefully this will help a bit more!
I’ve attached a .zip which contains some UE4 UAssets and a UE3 UPK which has the materials + textures that I’m using, if you connect the nodes in the UE4 material in the same way as the UE3 one, or if you switch on live node preview, you’ll see that the nodes are doing some different things.
I’m fairly sure that the UE3 build I used for this package was Either March or Feb 2013 
Hope this helps!
You’ll notice that the tiling of the material goes a bit funky when the nodes are connected up in UE4 the same way, at the moment I’ve just omitted those extra steps.
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Hi James,
Thanks for providing the assets and additional information. I was able to load them up and take a look and it appears to be functioning correctly in our internal build. Please look for the adjustments in an upcoming Rocket release.
Regarding the UE4 preview being completely blacked out on some nodes due to the negative values in the panners, our developers have indicated that this is an intended change from UE3 as in this situation they were not accurately representing the preview values correctly. Since there is no good way to visualize negative values, we display them as black instead of display an incorrect preview.
Thanks!
-W
Interesting, I’ll have our QA try to reproduce this in house so we can investigate.
