Original Post
Alright - the setup: I've got a 65x65 patch of vertices matched to a heightmap and slopemap - I don't have a problem generating a 65x65 normalmap (vertex normals), but for the way my process works I'd like to resample the maps to 512x512 (or 513x513 and I can cut the middle row/column out.) Now, I've tried a few small libraries for resampling with some small success in using a cubic filter (got some weird artifacts) and I don't mind that either the heightmap or slopemap use linear filtering as they're going to get some pre-built noise added to them probably and are just for texture-matching, but I'd like at least for the normals to be re-sampled up to a greater texture size so when I sub-divide the tile I'm on, I can go a few extra levels without generating a new normal map. Also, I'm aware that I can just put the normalmap as RGB and the Heightmap as the alpha channel - I'm just thinking in terms of speed. I'm trying to find some fast methods for cubic resampling of normal maps, either as a texture or as vectors - I tried a library called CImg and it gave me some unusual results, so I'm not sure what happened there. Sorry the question is a bit vague - feel free to ask for clarifications or more info. Thanks for any help you can give - Merry Christmas!