Uvmap Guide For Dummies
From Serious Sam Wiki
This article explains some basics of uvmapping with general usage in mind (advanced stuff like arranging the uvmap manually is covered elsewhere). Dummies only!
- Uvmaps are basically used to tell a texture how it should appear on a particular surface. You will typically need to create uvmaps for each particular element of your model for the textures to appear correctly. In case of a room, you would need an uvmap for the walls and the floor/ceiling. For instance, since the floor and ceiling are both on a flat plane, the same uvmap can be used for both of them. Likewise, slight changes in walls (such as beveled holes) can usually use the wall uvmap. Spherical parts would need a Sphere uvmap, and so on.
- Uvmaps can be stretched along the U and V axes for better display of the texture. It is usually difficult to manually arrange uvmaps perfectly, so stretching them is recommended as an easy solution to texture problems. Experiment with different stretch values for better results, for a wall with a cylinderical uvmap for instance, you can usually put stretch u to 10 and keep stretch v at 1 for a near-perfect looking texture.
- If stretching doesn't fix your texture problems, you can try creating a new surface or uvmap for the broken texture.
- Three uvmaps are typically needed for most models: a planar uvmap, a cylinderical uvmap, and an arranged atlas uvmap for enabling shadows (lightmap). In case of planar and cylinderical uvmaps, "fit both uv" option should be selected. To arrange the atlas uvmap, go to the uvmap tab (on the right) in mesh editor with the uvmap and its polygons selected, and choose Arrange (BSP). Arranging is usually recommended for nicer results. Shadowmaps should be named Shadow (see help on naming below). There are other ways to create shadowmaps, such as copying an uvmap from an existing uvmap, but atlas is the most simple and effective solution unless your model is very complicated.
- For special models, such as sphere shapes, you may have to try a little different uvmaps. Spherical models can use the sphere uvmap for instance. If all else fails, atlas uvmap should work on most simple shapes.
- Uvmap naming should be kept simple for usability's sake; it's recommended to name your uvmaps Texture, Texture2, Texture3 and so on. Shadowmaps (arranged atlas uvmap) should always be named Shadow, as that is the default shadowmap name for most Croteam models.
- Uvmaps can be further adjusted after you have created them by pressing Shift+S again and going to the Adjust tab (be sure to have the desired uvmap selected first!). You can for instance flip the uvmap along the U and V axes, which mirrors it accordingly to those axes. For instance, if you wish to make a door that appears to open from the middle, you could split the door polygon (surface) in half and create a seperate flipped uvmap for the other half, mirroring the texture. To put it simply: if you just want the texture to go some other way, flip it.