Soft terrain ... how to?

NAIMA

Hi I am curious about how is realized and what is the tech behind soft terrains like snow, mud, sand etc... just like seen in Red Dead Redemption II...

Any technical talk around?

defragger

dynamic terrain tessellation and displacement

NAIMA

Thanks, and how I can see how this works or is implemented ? I mean what kjind of maps, what engines do feature it etc?

TheGabmeister

Check this out. Deformable Snow Rendering in Batman: Arkham Origins

https://www.youtube.com/watch?v=87rg95XBalE

I think there's also a GDC talk about the deformable snow in Rise of the Tomb Raider.

NAIMA

Thanks, Do you have a link to that talk?

Mark Dygert

In Unreal you use dynamic tessellation and displacement, either on static meshes or on the landscape. You displace the mesh up however deep you want the snow and the collision is set by default to be at the original position of the mesh. If you want to set up footstep masking, then that gets a lot more involved but it's not terribly difficult.

Using Landscape
https://www.youtube.com/watch?v=WGbdMIFT_KE

Using Static Meshes and Render Targets
https://www.youtube.com/watch?v=WZfaVOHhiRc

If you want to take the quick way, there are systems available in the marketplace for fairly cheep
https://www.unrealengine.com/marketplace/dynamic-plane-deformation-blueprint-with-snow-demo 

NAIMA

Thanks I am just curious to know how... 
I noticed that in RDR2 its not just a layer iver terrain but snow has shapes and appearence due to Wind or cumulated by storm...
Any ideas on how they did that or did they say anything about?

Mark Dygert

I suspect they built those assets specifically for those scenarios on those areas of the map. I doubt they are doing complex weather simulations on snow, especially on a console. They might have used some complex simulations in Houdini or another 3D app to make those effects but they are baked out and rendered at much cheaper cost in the final game.

It also looks like they spawn meshes and decals around disturbed areas and then soften those effects over time to show the accumulation of snow.

They also use particle effects when the snow is disturbed to help sell the disturbance. They do the same when you bump into trees.