Hi, I am starting a track project and have a couple of questions that i would really appreciate some help on ; Does the track surface for any reason have to be welded to the infield or the rest of the terrain, buildings or objects in the track? can they remain unwelded/unconnected? If objects are seperate in the scene does that cause any problems with collisions or anything else in RF? Can you butt up objects to one another or even have them intersecting each other, whilst not welding their vertices? any tips on topology where an object of higher polycount must connect to a lower poly mesh like track to surrounding terrain? So i have read that it is best to use 4 sided polygons, is it an absolute no no to use 3 or 5 or anything else? kind regards Skynet
No, objects do not have to be welded together. In fact, it's often recommended to break up your objects (depending on size/polycount). About the only downside is that it's possible to get shading discontinuity there (i.e. a seam). This is really only noticeable if the polygons to either side are not coplanar (flat). Of course, this can be used to your advantage to get hard edges without needing extra geometry (i.e. bevels). A general rule of thumb--split into separate objects along "coplanar edges" for large objects such as track and terrain, but for smaller objects, only split into separate elements if you want a hard edge (and are exporting gMotor normals--which is advised). Yes, you can have objects intersecting. This can be a great polygon saver in many situations. However, it should be known that depending on how the final lighting ends up, it 'could' cause some shading errors--or even if you're using vertex colors (i.e. AO from vertex colors). I had some posts around that talked about doing LODs for the track--but the same principle 'could' be used for terrain to track blending. I'll try to add them when I find them. Yes, you can use 3,4,5,6,7,8...-sided polygons if you want to. It doesn't matter, because all the game sees is triangles, anyway. The reason people tend to recommend 4-sided polygons is because they tend to have evenly-sized triangles--which matters quite a bit for shading and things like RealRoad.
Quads are just so much easier to work with, especially down the road when you might want to add some polys for rounder edges. Other number of sides in polys are fine too though, it's more an ideal case thing to have quads if you can. On my trackside geometry like the grass between the road and guardrail there's few quads as the guardrail is usually "lower res" than the road, thus requiring say three road polys to connect to just one guardrail poly. Intersecting - I try to avoid it but there's cases where it's just that much quicker to just have them intersect, both to build and render. It works "best" if the intersecting polys are as far apart in angle as possible, i.e. close to 90°. Them being coplanar is the worst case, unless you use the decal tag it will give you z-fighting issues. Splitting - I only split (detach to element) what needs to be split, i.e. where I need hard edges or where I export to different .gmt files.
I think the margin of error is caused by discrepancy between system units and display units which both need to be set accordingly. I was going to work in Metric hope this is ok when it comes to modelling for RF2? Will look in to units setup some more tonight and will make sure its right before starting the project properly. .......Meanwhile have been experimenting with some terrain in the shape of an island using paint deformation on a 7km X 7km plane.
