PreviousFrameSwitch

Development Programming & Scripting
1

Hi, I have questions about PreviousFrameSwitch node in material editor, it’s supposed to enable motion blur and Temporal AA for vertex deformed objects (like alembic ones I guess). My question is, how do I actually use this node??? I guess that the output is supposed to go to World Position Offset, but what are the inputs? The current frame is a constant3vector (0,0,0) I think, but what about the previous frame? What do I plug there, if I plug another constant3vector with a different values I get a static motion blur kind of effect, what I guess I need is a display of motion vectors to plug in so that the motion blur works how its supposed to?

This is an example screenshot from the UE4 4.15 stream: Screenshot - 025cae019fc94dbd1336ffb008237a6b - Gyazo
It says I need “Accurate velocities from Vertex Deformation” (which I do) and velocity in GBuffer enabled (which I don’t), so how to enable velocity in GBuffer?

2

I have also found about this: https://i.gyazo.com/7700f7079447b410010c214f7a85be23.png (from UE4 docs), is there a way to display motion vectors like this? (I guess I need to plug that into previous frame input right?)

3

Well, kinda answered my own question about this (type in console: VisualizeTexture GBufferVelocity RGB UV0), but my first question still remains.

4

Heya,

Did you ever find an answer to this? I can’t figure out how to enable the velocity in gbuffer either.