Is UpdateNormals too slow?
Couldn't you cheat and cut the number of trinormal calcs in half? Instead of possibly 8 tri normals, use 4:
E normal = Average of trinormals EDB EBF EFH EHD
Won't be perfect unless EDB EBF EFH EHD 'are' the actual tris, if your terrain is built in an ordered fashion, E would normaly have 6 tris connected to it, unless it was at an edge:
EDB EBC ECF EFH EHG EGD
I can't see how you can get trinormals without doing cross products though.
Couldn't you cheat and cut the number of trinormal calcs in half? Instead of possibly 8 tri normals, use 4:
E normal = Average of trinormals EDB EBF EFH EHD
Won't be perfect unless EDB EBF EFH EHD 'are' the actual tris, if your terrain is built in an ordered fashion, E would normaly have 6 tris connected to it, unless it was at an edge:
EDB EBC ECF EFH EHG EGD
I can't see how you can get trinormals without doing cross products though.