I have an Atmo world which is 100% Viewpoint objects. It consists of a terrain, with a lake and river, and an area of dense vegetation, through which a path is cut. The explorer should not be able to deviate from the path, but should be able to wade into the water. The vegetation consists of billboarded planes that have alpha maps applied. Since textured planes never look that great close up, and collision does not always work well on them (it is possible to slide past them as they swivel) I have also added a 3D invisible wall either side of the path.

Now, here's the problem. Since the water and the plants do not need collision, but the path walls and the terrain do, I have placed the water and plants in one mtx file, and the terrain and path walls in the other. Then I put both mtx files in roughly the same place in the .aer, so that I could scale and fine tune the positioning of them accordingly.

However, when I publish the world, weird things start to happen. The terrain behind the transparent part of the billboard planes does not show - instead, I just get the lilac Atmosphere background, as if there was a hole in the terrain. It looks like my plants are floating inside lilac squares against the backdrop of the terrain.

I read somewhere in this forum that solid Viewpoint objects in the background not showing through transparent Viewpoint objects in the foreground, has something to do with the order in which you place things in the .aer. So I put each mtx file into separate folders, and swapped the order around so that the terrain mtx was above the plants and water mtx. This time, the terrain showed through the billboards perfectly, but the transparent part of the terrain (the path walls) blocked out the textured images of the plants. I also tried the path as a separate, third mtx file, but that just looked like I'd made a hole in the terrain the shape of the path, I could see the lilac background right through it. No matter how I shuffle the order of these mtx file around, I cannot get everything to show through everything.

The best I can manage is to have the plants in a folder lower down in the pecking order in the object inspector, than the terrain, and no path... and then everything seems fine - that is, until I move one of the mtx files along the x or z planes to fine tune the positioning, then the problem with the holes returns. So maybe it is not just the order of things that is the problem?

I know that it would make sense to put everything in one mtx file (because you can control the render order that way) but then either everything would have collision (which would increase load time) or everything would not....

Has anyone else experienced this problem, or knows a solution? For example, is it possible to apply collision only to certain instances in one mtx, or is there something I can do in the Atmosphere builder to fix this problem?

*ever hopeful*