How to make grass grow in daylight and stop at night unreal engine 4

Development World Creation
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Any walk through videos on How to make grass grow in daylight and stop at night unreal engine 4

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Hi @Wendy2025a

It really depends on how you want the game mechanics to work. Basically, the first thing you would need is a defined day-and-night cycle. Then, create a material that simulates grass growth, which can be done using a Timeline node to control a parameter that adjusts grass height via world position offset. You can then use a Blueprint to manage this parameter, starting grass growth during the day and pausing it at night. If you can share more information about your project, I might be able to give you more specific guidance on how to set it up.

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I wonder if a tutorial on this would be akin to watching paint dry.
You do use the expressions interchangably generally speaking…

Define Day.

Define night.

Define growth.

If growth’s definition is anything like the real thing - just forget about it; The engine can’t even render regular grass as a set of static meshes without running at 2FPS. A realistic growth isnt going to be possible (Done it on leaves. You can run maybe one single tree per level, and it’s much less demanding than grass).

Also define Application:

Recording a short/movie? Maybe. Fps doesnt matter there.

Running in a game? Not going to happen with unreal (at least for another decade going by hardware limitations).

Overall:
Changing grass height (which is not growth) is achevable by levaraging vector paint and stretching up on Z all of the vertex vased on said weight paint. The result is pretty much garbage on anything that looks like a good grass mesh and only barely acceptable on meshes you specifically make with that objective in mind.

BUT - you cannot run that shader on all your grass at the same time because performance would be below 0 fps.
So you have to curtail the effect to be screen based or localized around the player. And even that will likely topple most GPUs to where you cannot play.

Done right, not impossible. Much like the trees, but just not in this engine. Why tilt against windmills if you don’t need to?