Vertex Animation Export Sprites - missing particles and non-working Color map

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Hello everyone!
I followed Luiz Kruel's GDC Vertex Animation Project Overview (link: https://vimeo.com/207832662 [vimeo.com] ). I installed the HDA from its source files. I had luck with the FLIP sim mesh export/import, but the Sprite export/import is somewhat tricky.

In UE it seems to stop loading all the points it should after some time. It's noticable on the bottom, where in Houdini I am emitting new particles all the time, but in UE they are appearing from the middle of the height of the sim. So is there like a particle count cap, or why the new ones stop appearing?

Also if I use the Color Map (tick on its usage in the material and drag/drop it in the slot) the particles disappear completely. -That's why I saved the material without the use of the color map - so that anyone can at least see the particles, when they open the test level

I copy/pasted the min and max bounds from houdini
I correctly set the number of frames
On mesh I ticked on (and applied ) the “usefull precision UVs”
On textures I changed the filtering to Nearest

I use houdini Indie version 16.0.736 with the GDC version of the exporter HDA and latest UE4.

Thanks for any help!

Bye, Vasa.

Attachments:
vertex_anim_test.zip (14.0 MB)

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Hey Vasa,

In theory the particles should be getting recycled, with the ones that are dying moving back to where the original ones were.

It might be worth getting the new exporter too, Mike Lyndon upgraded it recently and has probably fixed a few bugs. You can grab it from https://github.com/sideeffects/GameDevelopmentToolset/tree/Development [github.com]

Make sure that the material is double sided as well, that has caused some issues before as well.

Let me know if those help you

Luiz
Luiz Kruel
Senior Technical Artist
SideFX
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Thanks a lot, Luiz!
After updating the plugin, everything worked perfectly.

One more question on UE (since you have a history with it ) - Is it possible to somehow control the playback of the vertex animation from ingame?

Is it through altering the shifting of the UVs in the mat based on time?

Or is there some easy way?

I'd like to be able to start/stop the animation from within the game, or from the editor somehow set the start of the playback.

Thanks a lot!

Bye, Vasa.
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The sprites are driven by a time node in the material. You could replace that with a dynamic parameter and use particle life or you could set the value through a blueprint (but I think that might be inefficient).

Mike
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Hi, Mike!
Thanks for the answer!

Yes, I thought it will work like that, I just wasn't sure about the best aproach though.
Thanks for clarification!

Bye, Vasa.
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mikelyndon-sesi
The sprites are driven by a time node in the material. You could replace that with a dynamic parameter and use particle life or you could set the value through a blueprint (but I think that might be inefficient).

Mike

Can you elaborate on how you can use particle life so that the vertex animation starts on the first frame only once, and then reloop on the last few frames.

Ive attached the vertex animation to a particle system , but all particles are playing the loop at the same time, so ive been unable to have a continuous emitting effect.

cheers !

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regift.gif (4.6 MB)

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I think what you would need to do is create 2 separate simulations. One for the start where the particles are emitted and then a second that loops. I don't think there's a way to do it one. So you would play the first simulation and when it dies start playing the second which loops. The last frame of the first sim should match the first frame of the second sim.
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mikelyndon-sesi
I think what you would need to do is create 2 separate simulations. One for the start where the particles are emitted and then a second that loops. I don't think there's a way to do it one. So you would play the first simulation and when it dies start playing the second which loops. The last frame of the first sim should match the first frame of the second sim.

so id have to render new vertex animation and color maps, with a different instance, material and mesh than the initial one? I thought there might be a way to loop the material instance to read the maps from a different frame number after looping once

what about using the subimage index ?


thank you for your help
Edited by zyadM - Nov. 24, 2017 08:29:50
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zyadM
mikelyndon-sesi
I think what you would need to do is create 2 separate simulations. One for the start where the particles are emitted and then a second that loops. I don't think there's a way to do it one. So you would play the first simulation and when it dies start playing the second which loops. The last frame of the first sim should match the first frame of the second sim.

so id have to render new vertex animation and color maps, with a different instance, material and mesh than the initial one? I thought there might be a way to loop the material instance to read the maps from a different frame number after looping once

what about using the subimage index ?


thank you for your help




Found it!
you can use particle relative time instead of world time when setting up UV scrolling in the material
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