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What is the correlation between "No Weight-Blend" layers and the "Alpha Blend" blend type?

Hi
When you create a Landscape Layer you got the option between a “Weighted(normal)” Layer and a “No Weight-Blend” layer.
When you use a Landscape “Layer Blend” node in the material graph you can choose between 3 blend modes: Alpha Blend/ Weight Blend/ Height Blend.

I wanted to ask,
First: what is the correlation between these 2 layers types and the 3 Blend Types?
Second: Must I use “No Weight-Blend” layers only when I want to use a “Alpha Blend” blend mode?
In the documentation it is advised that the first layer in a “Layer Blend” node should have the blend type “Alpha Blend” to avoid black patches in certain portions of the landscape. Should this layer also be set to “No Weight-Blend”?
**Third: **On the documentation it is also advised to use “No Weight-Blend” for layers like “Snow” and “Puddles” who are supposed to be on top of the blended material stacks no matter what. Does that mean that if I want a Snow layer I should use “Alpha Blend” blend mode in conjunction with a “No Weight-Blend” layer?
Fourth: If, in a material which has already a stack of layers blended together with a **Layer Blend node, I intend to add a layer with the unique purpose to be used in conjunction of a landscape Layer Sample node, rather then be added to the Layer Blend **node, should this new layer be created as a “No Weight-Blend” layer? (For instance to create a “Puddle” mask where I will use this mask to multiply some roughness and specular with a certain value).

Thanks

  1. Despite the similarity in the names, the landscape layer type is not a technical requirement for the blending method used in the actual material. Once painted (or imported) both types of layers contain weighting information that’s treated in the exact same way in the material.
    The layer type controls how the weights are added or removed WHEN PAINTING, and the blend type controls how those weights affect the layer blending in the material.
    Certain combinations were clearly intended by epic to be used together more often than others, hence the confusion.

  2. No - as the docs state, even with all your landscape layers set to ‘weighted(normal)’, you probably want at least one layer in your material blend set to ‘alpha’ to avoid certain artifacts

  3. Likely yes, though this isn’t a technical limitation - more of a recommended workflow to prevent painting landscapes being annoying / frustrating / difficult to control. If you set up your landscape like this, you won’t take into account the height of the other layers when blending in the puddles, which you might want, so it’s not a rule.

  4. Again, likely yes, depending on your use case - you probably don’t want this layer to remove weights from other landscape layers when painting.

As a general rule of thumb. Use no weight blend on layers that can go over other layers - for instance landscape grass layers and other procedural which can all coexist.

Use weight blend for base material that are exclusive (and the base material should be set to no weight blend probably.

Thanks @Scribbler
and thanks [USER=“3140864”]MostHost LA[/USER]
I think I finally understand.

As a follow up question on this theme, if I have a “layer blend” node which is blending between 4 “Weighted(normal)” biomes/materials , like desert, tundra, *prairie *and marsh, one of these must be setted to “alpha blend” instead of “height blend”.

The question is which one?
Meaning, does that layer loose the height blending capability when painting right? I would really like each of them to have this feature, so is there any workaround that is not too expensive? Like creating an extra simple base layer set to “No Weight-Blend” and “alpha blend” with not textures? Would something like this work?

Thanks!

Doesn’t have to be. But usually the very first layer of the blend - and you also need to fill the landscape with it and paint other stuff on top.
which to me is a red flag. You pay the cost of 2 layers on everything if you look at the shader cost. I prefer artifacts to that :stuck_out_tongue:

Make a near empty layer with a neutral grass. Only 1 texture. And use that as the base with no blend so it’s the cheapest cost possible without using a solid color.

To be honest, I have seen 0 artifacts/black spots so far, I only seen that everyone strongly advises to do this procedure, so I was being cautious. I also would prefer a few artifacts to add another layer. It takes already a lot of time to compile it so it might just not be worth it.