Translucent material visible render lag

Development Asset Creation
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1

We are using a translucent material for windows. The windows have dirt and grime added via texture in the material.

When moving the camera in the scene there is a visible lag on the movement of the dirt on the window. This scene is being put on an LED volume where the issue is considerably magnified in scale and noticeable.

The current material in the scene takes advantage of subsurface features, but I have reproed with a variety of different shading models, textures, ppv settings, approaches.

I still see the lag whenever the dirt and grime is translucent.

How would we remove or mitigate this?

2

Hey George,

On the Main/Master Material of that glass can you try and go under the translucency submenu and enable Output Depth and Velocity. This should help inform the AA systems a lot better.

3

Steps to Reproduce
In Repro project attached:

Level: /Game/PL_WindowDirtRepro

There are multiple SLs with different approaches to glass in each.

SL_PEN_Content and SL PEN_LIT_02 should be visible for all glass SLs.

SL_SubsurfaceGlass is our hero glass.

All blueprint loaded glass SLs are alternate tests.

Only one glass SL should be visible at a time.

To repro, go to this camera position: BugItGo -886.572808 -184.016915 489.958372 -10.759924 1989.396593 0.000000

Camera speed should be slow, <0.1.

Use A and D keys to track side to side and watch the grime on the windows.

The lagging is more noticeable to the eye over the brighter sky color and looks like it is not happening at the edges over the window mullions.

4

Yeah, that’s the trade-off, unfortunately. Less aggressive real-time AA.

5

Repro project didn’t attach, here it is again.

6

Thanks Shaun,

This fixes the issue with the glass. However, we’ve noticed that it causes an issue with the environment behind the glass.

Before, the dirt on the glass looked streaky/laggy on movement. Now, with Output Depth and Velocity on, the BG behind the glass looks streaky/laggy on movement. Is there a way to counteract that or is that the trade off of that setting?

7

Copy that, thanks!