What is the cost and viability of conditional materials with open world level streaming?

I’m looking to build a large scale open world with changing seasons. As far as I understand, importing a tiled landscape with level streaming/world composition enabled will subdivide the overall world into separate levels as defined in the imported file. Can I use Landscape Layer Switch (or something similar) to assign different layers of landscaping materials based on a Season boolean value when the level loads? How will this impact performance?

Another question ( Conditional statement in material - Rendering - Unreal Engine Forums ) mentions conditional statements in materials, which would be useful for un/applying a snow layer on trees or grass, although that leads me to my second series of questions-

Is there likely to be much of a performance impact in loading different tree models based on a seasonal value? Can I assign conditional foliage? Also, how might this impact LODs?

Thanks! This is exactly what I was looking for. That’s a shame about foliage blueprints, but this is a long-term endeavor, so as long it’s on the to-do list, I can be patient.

You could use Material Parameter Collections to make global changes in materials like seasonal changes you mention. As to replacing the foliage meshes in run time, currently it is not possible without touching the source code(and i wouldnt know how to achieve that with code) but we will be able to use blueprints as foliage in the future so that may be the solution for this.