(2020-07-21, 23:13)Travis Cobbs Wrote: That is definitely not true. I believe that you are misunderstanding TEXMAP.
If the texture is drawn over a single quad, then the blank version of that exact same quad is perfectly legal. In this case, that quad would be a geometry2 quad, and would logically use !TEXMAP NEXT, since it's a single geometry line. If a texture is displayed over multiple triangles and/or quads, then START/END is required, but omitting the texture would still show blank geometry in the same place, as long as they use geometry2.
Obviously, anything in the geometry1 section would be ignored by non-TEXMAP compliant renderers. So, if there is a geometry1 section, then it is almost certain that there should also be a FALLBACK section. Requiring this in the official parts spec is reasonable. But the easiest way to make a textured part is to simply leave the textured geometry blank for non-TEXMAP compliant renderers. So disallowing NEXT and geometry2 in official parts is wrong.
I agree
geometry2 is basically shared code (between the textured and fallback version)
NEXT is only useful for simple shapes (e.g. sticker quad), and as Travis explained it is its own fallback (the plain quad)
bit off-topic:
Something that does bother me a bit though, is the fact we seem to assume the textured version is 'better'.
This is not always true. The textured version could be faster to render and even give nicer results (especially on curved surfaces) but in many cases a vector representation will result in higher details upon zooming.
So unless we allow vector formats alongside png the textured version is not always visually the best solution.
For this reason I find the whole 'fallback' term a bit misleading, I wouldn't mind some hint system in order to let the renderer choose fallback over textured in some cases.