What actually are LB_AlphaBlend, LB_HeightBlend, and LB_WeightBlend

Don’t suppose documentation bugs go here, do they?

I can’t find a description of what LB_AlphaBlend, LB_HeightBlend, or LB_WeightBlend actually do, and how they work. I can find a bunch of stuff telling me I should have a single LB_AlphaBlend layer in a LayerBlend node, while the rest use LB_HeightBlend, and I’ve worked out that LB_WeightBlend was not an option originally, but I can’t find anything that discusses how they work, in any detail.

Could this page, or the correct page, be updated to actually talk about them?

Or, if I’ve just failed to find something that is in the documentation, could you let me know where it is, please?

EDIT:

I’ve been pointed to Landscape Material Layer Blending in Unreal Engine | Unreal Engine 5.1 Documentation

Essentially the difference is how many layers of information you have of information:

  • LB_WeightBlend gives you a weight map. A weight map is where you have a single layer of information saying: this pixel is material 1, this pixel is material 2, etc. A single splat map is a weight map.

  • LB_AlphaBlend gives you a layer, or mask, per material. So if you have material 1 (rock), material 2 (grass), material 3 (snow), then you are painting a black and white mask for each of these materials, or layers, to determine where they are. If material 1 is on the bottom and material 3 is on the top, then painting material 3 over material 2 or 1 would layer the snow over the grass or rock. When you erase it, it would go back to the material that was there before, as the layer for the rock or snow is not edited. This is different to a weight map, as you only have 1 layer of data, and painting over the data removes the data that was previously there.

  • LB_HeightMap is a weight map, which adds a height map in transitions. So if you have a wet layer under a dry layer, you can apply an appropriate weight to make the material wet in crevices, or something similar. The LB_HeightBlend result image below the linked table is, I think, a good visual description.

I was looking for an answer to the same question and found this page, which explains it in more detail:

I have the feeling that I didn’t quite understand it to the fullest yet, so I am not trying to explain anything here, as I may be utterly wrong. I, however, hope that the page may help you understand it a little better.

Hey thanks for the response. Now that I’ve seen that I do believe that I understand it. I’ll edit the original comment with an explanation.

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