r.SeparateTranslucencyScreenPercentage bug with worldPosition as UVs

Development Rendering
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1

I’m using worldposition to drive some uvs and when I lower the translucency screen percentage, the textures swim around when the camera turns. looks like the world position input isn’t being scaled with the resolution change.

2

Hey dokipen,

Could you provide me with some screenshots and simple steps to reproduce the issue on my end?

I am familiar with the settings you are mentioning, and there are some known issues with WPO, but I would like to see if what you are seeing is related to the reported issues.

Cheers,

3

Sure. The easiest way to see it is with a cube and noise node.

Make an unlit material with a noise plugged into it (lower the scale so you can see the noise pattern). I’ll try and get a scene together.

4

That would be appreciated. Once I can get a reproduction case in front of me, I can move forward with the bug reporting process.

5

Here you go andrew.

Just open up project (4.11) and set r.SeparateTranslucencyScreenPercentage to 50 pc.

Cheers
Dan
link text

6

Thank you for taking the time to get a repro case over to me. I was able to verify what you are reporting and have gone ahead and entered a bug report for the issue (UE-30267). I will say I did find a temporary workaround to the swimming of the textures, by disabling the ‘Separate Translucency’ option within the material editor.

Once the fix has been made it will be added into an upcoming full engine release or hotfix, and added to the list of known issues. If you have further questions or need additional assistance, please let me know.

Thank you,

7

Cheers glad I could help.

I think to get the option to control the resolution with that primvar then the material has to have that option turned on. I believe that is what enables it to be possible because that material goes into its own separate buffer which has its own resolution(which must be part of the problems). Anyway I’m sure someone will find a fix for it.

8

Thanks for reporting this and the simple repro. WorldPosition and ScreenPosition have been fixed for downsampled separate translucency in

cl 2984423
5/19/2016 6:27:12 PM
Fixed WorldPosition and ScreenPosition for downsampled separate translucency by scaling SvPosition before those computations. The View uniform buffer still contains incorrect buffer sizes for this pass.

This will make it into the 4.13 release.

9

Thanks so much !

10

Uh oh, just seen this…

Change 2994849 on 2016/05/31 by .Wright

Disabled fix for WorldPosition and ScreenPosition in downsampled separate translucency, since it breaks GetScreenAlignedUV (used in DepthFade), since the uniform buffer still contains full res buffer sizes

Any other fix ideas coming? I had a similar issue when using custom depth within a post process with worldposition and changing r.screenPercentage. Same problem I’m assuming.

Cheers
Dan