I’m stuck. (topology for the cloth)

mountains

Hi Polycount forum, 

I am modeling a tent. In Unreal, I want to animate the fabric, but my problem is that I don’t know how to model this shape since I’ve never made a form like this before and I also plan to add a small amount of thickness to the cloth. I’d appreciate any help with this. Will the topology I sketched in red work? 

I want the tent’s fabric to have some subtle movement as well, and I’m open to any suggestions on how to achieve it.

Thank you in advance

Eric Chadwick

What is the end intention? Is this to be in a game, as a looping ambient animation for a prop asset?

Assuming this is the intention, I would suggest pre-baking the animation into bones, and using skinning to animate the meshes. This is highly performant, but not interactive.

To do this you could create the initial mesh using a cloth simulation tool like Marvelous Designer. Which will give you natural-looking creases and draping. 

Then you could animate some bones to replicate wind-like behavior, and weight the vertices to the bones.

Eric Chadwick

To add some subtle wind-like rippling animation, I would suggest using a normal map of fabric ripples, and scrolling this across the surface, masking it to reduce as it nears the edges (perhaps using vertex color as the mask).

Do you have some reference video of what you're aiming to achieve? Super-essential I think, to guide you towards something that looks good.

I'm not endorsing this product, but there are some nice animated GIFs of tent fabric here: https://backercrew.com/skynest-ultralight-hammock-tent-all-in-one-quick-setup/

pior

Hello ! Always loving the JuniorSenior avatar

Along the lines of the suggestions from the Great Eric, and considering that the goal is an actual game asset for UE, then simply start by modeling a first version of the final polygon game asset of the tent at rest.

Garment making tools may be useful to an extent since they would generate some nicely evenly distributed tris or quads, but given that you are making a mere tent this is not really needed - just model things manually and keep things even, at least for a first version.

Then, get that first static version in game (perhaps with temporary UVs as that wouldn't hurt) and : 

- After observing it for a while, start thinking about your course of action for the modeling of final version (like whether or not you need baked details, establishing the overall level of detail that you actually need, and anything else of that nature). You could also try to see how far you can take this first model with clever texturing alone. My bet would be that it would take you 90% there.

- Then, start experimenting with the many animation/dynamics tools at your disposal : like pre-baking the animation (either as Alembic vertex motion, or as a simulation baked onto bone clusters as suggested above) or creating said vertex animations either by hand or by sim ; but also exploring what the in-engine tools can do (cloth sim applied to certain regions of vertices, vertex shader node in the material for subtle sway, and so on).

- And then start worrying about the final asset once you reach a decision on all of the above.

In other words : get your full tech stack locked first and foremost, on a temporary asset that doesn't even necessarily need to look like your final.

IMHO your most reasonnable course of action is probably to just run a sim on your final low (in Blender) and bake that to vertex animation for export. Hence zero calculation on the engine, just playback, therefore no bottleneck for performance. But if you just need some very subtle sway, then a mere vertex motion on the material (maked by vertex colors) would be more than enough.

Here's a scene from Ground Zeroes (an exceptionally well optimized game with great performance and still looking fantastic today). I bet that the these tarps moving under the storm are either fully pre-baked as vertex animation, and/or using some clever (but very lightweight) vertex shader for noise (at the 13mins mark).

https://youtu.be/8e88I1CFKu0?feature=shared&t=787