Okay, I have two adjacent terrain tiles. I used UpdateNormals() to calculate most of their normals, but the edges need to be "locked" so there isn't a visible line between terrain tiles.
I find the adjacent vertices, sum their normals, then normalize and set both vertices to this same normal. This looks a lot better, but I still have a little bit of a visible line between them in some spots. By definition, summing the normals and normalizing should give a really smooth result that looks good on both the tiles...but I can still see as line. Any ideas?
nx#=(VertexNX(surf,v0)+VertexNX(topsurf,v1))
ny#=(VertexNY(surf,v0)+VertexNY(topsurf,v1))
nz#=(VertexNZ(surf,v0)+VertexNZ(topsurf,v1))
mag#=Sqr(nx*nx+ny*ny+nz*nz)
nx=nx/mag
ny=ny/mag
nz=nz/mag
VertexNormal surf,v0,nx,ny,nz
VertexNormal topsurf,v1,nx,ny,nz
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