> Yes, I think that's a very good idea; in fact, if you wanted to go to > three layers, the furthest one could be simply untextured, coloured > polys (that's what you'd see from 120,000ft, for example). For each > tile, we need to sample to find the commonest material and then use it > for the texture (and/or colour) at load-time.
Each tile has a replacement of a single color at the lowest altitude in that tile at the near edge and the highest altitude at the far edge. These colors and altitudes are stored in textures that are statically computed in TerraGear. I figure a couple dozen textures can do the whole planet; of each texture pair, one does the color without alpha and the other uses the RGB to store that altitude information. > Curt is worried about joining meshed tiles (with irregular terrain) to > flat tiles, but I don't think that will be a big problem if the flat > ones are far enough away. If we wanted to, we could also sample the > elevation variation for each tile to help us decide how far away it > should be drawn as a full mesh: flat tiles could go to a single poly > much earlier than mountainous ones, for example. We start with the whole planet only being those thousand-mile textures, mapped onto the sphere at sea level altitude. When the viewpoint is closer than a thousand miles to any of those textures, it gets broken up into triangles of the same texture mapping and the altitude data is used to position the triangle above sea level somewhere. When tile-pixels are more than 10 screen pixels wide, i.e. nearer than 400 miles for most, we load and draw full tiles. _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
