Because this question reappears every month or so i decided to make illustrated howto rocks.
First you need blocky layout of your level. It needs to be single mesh without holes and if possible no triangles. Convert that mesh to poly in max.
Edit: by holes here i mean open borders inside of mesh or unwelded vertex and such errors, those appear as nasty artefacts later in zbrush.
[SHOT]http://nawrot.windglider.net/forum/rocks01.jpg[/SHOT]
Tessellate it manually so all faces are nice even squares (this help greatly when vertex painting later). To tessellate select one EDGE then use ring+connect in max.
[SHOT]http://nawrot.windglider.net/forum/rocks02.jpg[/SHOT]
Remove unnecessary surfaces. And now mesh is ready to sculpture in ZBrush or mudbox. Or if you do not have those use max with soft selection.
[SHOT]http://nawrot.windglider.net/forum/rocks03.jpg[/SHOT]
Mesh imported from max and subdivided to 200-300k. Now i torment it until i have result i like. If you want create normalmap in zbrush its good idea to uvunwarp before importing.
[SHOT]http://nawrot.windglider.net/forum/rocks04.jpg[/SHOT]
When you satisfied with mesh look its time to pick subdivision with poly count that fits your map. I pick poly count that will result in 4000-8000 polygons per mesh after i split this one. In this case it was 20k one, because i decided to split that rock into 4 meshes.
[SHOT]http://nawrot.windglider.net/forum/rocks05.jpg[/SHOT]
Back to max, and UV unwrapped. You should UV map whole rock in way it has no visible seam textures besides horizontal floor or roof surfaces. Try to minimize vertical seams. There is great way to hide horizontal ones but it work bad for vertical: Worldposition node used to UV map floor texture instead of mesh UVs.
[SHOT]http://nawrot.windglider.net/forum/rocks06.jpg[/SHOT]
Kepp first UV chanell for mesh in 1uv space something like on this picture. You can pan and scale textures on mesh later in UDK. More reasons for this posted at end.
[SHOT]http://nawrot.windglider.net/forum/rocks07.jpg[/SHOT]
This is how i split for purpose of this howto.
[SHOT]http://nawrot.windglider.net/forum/rocks08.jpg[/SHOT]
After splitting mesh do not modify first UV channel, you have seamless rock texture that you really do not want to mess with. Second UV that is used for lightmaps is different matter, cut and resize those shapes until you use 1uv space in best possible way. This is that "V" shape split into 2 and resized:
[SHOT]http://nawrot.windglider.net/forum/rocks09.jpg[/SHOT]
This is almost final result you can get with vertex painting and material that blends textures. Level is far from complete, I stopped making it at layout stages, no global normal map yet, and it has very basic vertex painting.
[SHOT]http://nawrot.windglider.net/forum/rocks10.jpg[/SHOT]
This method has one big drawback if you want to keep UV mapping seamless. After every change you need attach all meshes together then uv unwarp whole thing and split again. This is also reason that "final" picture is far from final level of detail.
When you have final version of mesh you can vertexpaint it in udk, or max, or make RGB mask texture to blend materials. And fact that first UV channel is in 1uv space and same for all meshes after split makes much easier to paint such mask. Also keeping square faces all the time really helps with detail you can achieve with vertexcolors. If you decide to use mask texture you can optimize whole mesh before splitting with decimator plugin in zbrush or in max.
First you need blocky layout of your level. It needs to be single mesh without holes and if possible no triangles. Convert that mesh to poly in max.
Edit: by holes here i mean open borders inside of mesh or unwelded vertex and such errors, those appear as nasty artefacts later in zbrush.
[SHOT]http://nawrot.windglider.net/forum/rocks01.jpg[/SHOT]
Tessellate it manually so all faces are nice even squares (this help greatly when vertex painting later). To tessellate select one EDGE then use ring+connect in max.
[SHOT]http://nawrot.windglider.net/forum/rocks02.jpg[/SHOT]
Remove unnecessary surfaces. And now mesh is ready to sculpture in ZBrush or mudbox. Or if you do not have those use max with soft selection.
[SHOT]http://nawrot.windglider.net/forum/rocks03.jpg[/SHOT]
Mesh imported from max and subdivided to 200-300k. Now i torment it until i have result i like. If you want create normalmap in zbrush its good idea to uvunwarp before importing.
[SHOT]http://nawrot.windglider.net/forum/rocks04.jpg[/SHOT]
When you satisfied with mesh look its time to pick subdivision with poly count that fits your map. I pick poly count that will result in 4000-8000 polygons per mesh after i split this one. In this case it was 20k one, because i decided to split that rock into 4 meshes.
[SHOT]http://nawrot.windglider.net/forum/rocks05.jpg[/SHOT]
Back to max, and UV unwrapped. You should UV map whole rock in way it has no visible seam textures besides horizontal floor or roof surfaces. Try to minimize vertical seams. There is great way to hide horizontal ones but it work bad for vertical: Worldposition node used to UV map floor texture instead of mesh UVs.
[SHOT]http://nawrot.windglider.net/forum/rocks06.jpg[/SHOT]
Kepp first UV chanell for mesh in 1uv space something like on this picture. You can pan and scale textures on mesh later in UDK. More reasons for this posted at end.
[SHOT]http://nawrot.windglider.net/forum/rocks07.jpg[/SHOT]
This is how i split for purpose of this howto.
[SHOT]http://nawrot.windglider.net/forum/rocks08.jpg[/SHOT]
After splitting mesh do not modify first UV channel, you have seamless rock texture that you really do not want to mess with. Second UV that is used for lightmaps is different matter, cut and resize those shapes until you use 1uv space in best possible way. This is that "V" shape split into 2 and resized:
[SHOT]http://nawrot.windglider.net/forum/rocks09.jpg[/SHOT]
This is almost final result you can get with vertex painting and material that blends textures. Level is far from complete, I stopped making it at layout stages, no global normal map yet, and it has very basic vertex painting.
[SHOT]http://nawrot.windglider.net/forum/rocks10.jpg[/SHOT]
This method has one big drawback if you want to keep UV mapping seamless. After every change you need attach all meshes together then uv unwarp whole thing and split again. This is also reason that "final" picture is far from final level of detail.
When you have final version of mesh you can vertexpaint it in udk, or max, or make RGB mask texture to blend materials. And fact that first UV channel is in 1uv space and same for all meshes after split makes much easier to paint such mask. Also keeping square faces all the time really helps with detail you can achieve with vertexcolors. If you decide to use mask texture you can optimize whole mesh before splitting with decimator plugin in zbrush or in max.
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