How do I use Particle Cutouts in 4.11?

Development Asset Creation FX
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1

We just implemented the 4.11 preview build into our project and I am currently trying to figure out how to use the new feature “particle cutouts” described in your stream here:

In the stream it is stated that the exact method of how to use this feature will be explained in the full 4.11 release notes, yet I have the feature before me and would like to start implementing it. Can someone quickly explain how to use this feature?

I have the SubImage Index in the Emitter referencing the SubUvAnimation for the specific flipbook image, I just can’t figure out the next step.

Thanks!
-Alex

2

Hi Alex -

Setup Steps:

  1. Create a new SubUV Animation asset off of the flipbook texture (from Right Click menu in Content Browser)

94993-material.png

  1. Open the SubUVAnimation asset and make sure the SubUV Images Horizontal and Vertical are set correctly. (These two steps need only be done once per flipbook.)

94994-animation.png

  1. In Cascade, find the SubUV module and assign the Animation asset

94995-modules.png

You will still need to setup your particle system and material to use Particle SubUVs as previously in the engine as well.

I have a small sample project setup below for you to examine as well. If there is anything additional you need please feel free to comment back.

Thank You

Eric Ketchum

[Test Project 4.11_preview 6][4]

3

Ok, I see what I was doing wrong. This method does not work with GPU type data. I removed it and now it works.

Since it is now generating meshes for each emitter, does this mean we are spending an extra draw for this method as well?

Thanks for the quick and detailed response Eric!

4

Hi Alex -

All Sprite Emitter will generate a set of two triangles in order to render the sprite, the SubUV Animation essentially adds a few vertices in order to eliminate the overdraw caused by using the standard 2 triangle plane.

Overall, the cost of the extra vertices is significantly less than the overdraw generated by a flipbook. My test asset flipbook is a bad example since each frame mostly fills the individual UV space, but something like an explosion flipbook which begins very small then grows to fill the UV space, would get a much greater boost from this method.

In the SubUV Animation file you can set the Bounding mode which will allow you to control how many new vertices are generated, so you can balance the number of vertices with the amount of overdraw.

Eric Ketchum