Get Landscape height in material applied to a static mesh

[Deathrey (DeathreyCG)]

so far these are the limitations I’ve found:

• decals won’t have the landscape tessellation so you might notice that when the decal reaches the rock mesh, the landscape texture projected on the mesh no longer has the tessellation and instead just matches the mesh topology. but unless you use some crazy high displacement it’s not really visible (in my screenshot above it’s really not evident)

We can live with that.

so far these are the limitations I’ve found:

• another small limitation is that the decal rotation ‘contributes’ to the normalmap, so the more uneven your landscape is, the more spots you’ll have where the decal lighting can feel a little off. but since I fade the edges of the decal anyway, there will never be a hard transition so it’s quite alright

Normal projection for decal is dependent on decal rotation. Suggest skipping tangent space normals, and outputting world space normals by rotating result of normal map sample based on difference between world up and decal up vectors.

so far these are the limitations I’ve found:

• since I rely on WorldPosition-XY as UVs, if the decal gets projected on a vertical surface it will stretch really badly. decals don’t seem to have any angle filtering options, and the decal material is limited to either reading or writing the world normals (but not both) so it’s not trivial to reduce the opacity based on the projected angle (reconstructing the normals from depth might work but it’s not accurate and adds to the cost anyway). this for me is the biggest issue at this point. I could stop using WorldPosition-XY as UVs but then the magic of having the landscape texture match the decal 100% would be gone

Well, yes.
Indeed, you can use partial derivative of underlying position to estimate normal, that you would use to blend between projections.
Generally, I don’t agree here, that it is game breaker. It most cases it is safe to leave it as it is.

But this issue is tied together with another one. You really need those underlying normals anyway to get rid of lit backsides of the mesh, where the decal rotated normals to point towards the light, while it should be fully shaded.

about drawing the decals as instanced static meshes, I fail to understand what you mean
the rocks/meshes can indeed be added as foliage to reduce drawcalls (but that’s irrelevant to the blending we’re discussing). unless you mean using Mesh Decals somehow? (but they are terrible)

I will revert with clarification a bit later.