How can I use linear and surface vector information on the terrain surface?
As the terrain surface changes due to triangulation refinement, an easy way to keep the linear and surface information is to make an offscreen image of the desired information at the same resolution as the highest resolution textures and with 4-component rendering selected (i.e., using setComponents(SoOffscreenRenderer::RGB_TRANSPARENCY)). This offscreen image can then be supplied as an overlay texture to the texture preprocessor and merged with the other textures. For example, to add country borders to your terrain, you can make an offscreen image in which the borders are opaque and everything else is transparent. Then supply it as an overlay texture to the texture preprocessor.
