Growth Mesh Effect

Does anyone have some pointers on creating the effects that Ivy’s plant growing?

I think Arkham knight was done in Unreal not sure. But I wonder if this effect can be created in Unreal

I am going to try and rig a plant mesh but the effect is not the same
I think its done with spline meshes in but I can’t find a good explanation of how to weaponize it or use it as an ability in Unreal like they do in games like Paragon.

How about exporting as an Alembic cache? Then you can make however fancy rig you want in your DCC app.

I’ve used Alembic caches a lot, and I love them, but I haven’t tried them in Unreal unfortunately

Arkham Knight was unreal 3 and this effect is 100% achievable in stock unreal for sure!

I didnt do this particular one - this was done by one of the incredible character artists - although I did a ton of the other plant stuff.
The way I’d do it is just store two states of the mesh - there’s a ton of tools to store morph targets in static mesh data now, at the time we just used a UV set for full precision - and then simply blend between State A - thin and invisible, ungrown and State B - the default mesh state/fully grown.

Make sure the fully grown version is the one you have as default so you get nice normals/lighting etc.


I’m not sure how much overhead their is in Unreal Alembic importer, but using alembic for this seems overkill, you could most likely get away with using a vertex texture animation for this.

Alex above has definitely the most traditional method with some morph targets!

Importing an Alembic file into Unreal effectively makes it a skeletal mesh with each frame being a morph target

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So here are some tests that I have done with Morphs and Unreal. I am using Maya and Zbrush to sculpt the morphs/blendshapes
I have a tree mesh Rigged with chunks of the branches rigged as well.

This one the tree is animated bending forward and I used the curves in Unreal to control the Morph

This is with an Alembic file and it got funky I am not sure it baked right or not.

Neither of these are the best and I think I need to pose the tree mesh and then use the morphs to animate it only. But to get the effect of the growth I think I need to morph in sections and “Grow” it gradually. That sounds like it would not be an efficient use of time use of time.

At the moment I only have one morph of thin to thick. Is there away to control where the thickness occurs in the Engine or so I just need to morph in sections and gradually.

I think I am making this harder than it should be

yes the Alembic looks broken

It’s not an easy task to make a growable tree and two states will probably not be enough. As you suggest, growing it gradually with a few extra morphs in-between will most likely be better. Creating these in-between states is the difficult part I think

Controlling thickness in engine? Maybe with a clever shader, where you have a gradient mapped over the length of the tree or pivot painter for growing the branches

Maybe try to create the tree model in a more flexible way to make animating it easier? Possibly in Maya using Curves, circle extrude, NURBS. Then again, I don’t know how many trees you need to do

You also should keep in mind not change the vertex count/ order when working with morph targets

jsut in case How about vertex animation transfer from Houdini??
You can use skeletal animation too with this, I made most simple test.
Please check it :slight_smile:

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How much control does the houdini file give in unreal?

This effect is for an ability that can held/charged and will also be a bridge function to get across trenches

From what i understood from houdinis files and effects need to be timed in houdini and can’t easily be moded in unreal engine. Like a building blowing up is fine but the effect was time locked and so on. Unless i am thinking about something else

I wonder if the mash network in maya with the blendshape node would work and if that mesh can be baked and exported

It is very easy to modify sideFx’s ue4 material for control play time by parameter or dynamic parameter so, I think You can play that effects by Sequencer, BP or particle system.
also you can transform


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