> It would be pretty easy to write a python script that would convert all
> faces in the scene to one-sided.
I really don't want those faces to be converted to one-sided. I like
them as they are. I just don't want the .ac exporter to trash the few
ones I purposely set as double-sided.
> I think you are also confusing two issues. The fact that objects are
> created by default with two sides is the work of the Blender developers.
> In the context of making computer animations, this is probably the right
> choice. The decision not to honor this data when exporting was made by
> Willian Germano, the developer of ac3d_export.py, so people wouldn't
> have to do a lot of work flipping them back. I also think that this was
> a correct decision, though perhaps offering both behaviors in the
> exporter would be better. Willian accepts patch submissions, so that is
> another possible solution to your problem.
Maybe I was not clear. I already have one-sided faces.
My .obj files contain only one-sided faces objects. I import the .obj
file into Blender and faces still remain one-sided (that's ok). I am
modelling for FGFS, one sided faces are enough for almost any purpose.
Then I add texture maps to the 3d object inside Blender, maybe I tweak a
few vertex too, and finally I export it to .ac format and I get correct
one-sided faces into my ac3d file.
Well, the problem is when I want just a few of those faces to be
double-sided, I'd like to to that into Blender (since Blender is capable
of specifying that), but that's useless because the .ac export converts
them back to one sided again! :-(
>>Sorry Josh, I disagree with the above method; duplicating faces in order
>>to get double sided rendering into FGFS is not a solution to me at all.
>>That just increases the geometry and has bad consequences on
>>performance. I would not suggest this solution to anybody.
>
>
> Actually, this is not the case. There is a small performance hit on
> model loading because the extra data for that surface must be loaded.
> Once in memory however, it makes no difference. Plib converts 2 sided
> ac3d surfaces into duplicate 1 sided ones in memory and flips on set of
> normals for the simple reason that there is no such thing as a 2 sided
> poly in either openGL or a graphics card. This duplication also created
> a one time performance hit, but since the disk isn't involved it is
> smaller. From this point on both methods are equivalent.
That's interesting. That means a two-sided face takes double the memory
of the GPU (once loaded) then the one-sided version.
>>By the way, FGFS does not resemble reality with high fidelity at all;
>>ok, it aims to that, but we are far from that. In the meanwhile, we
>>accept a lot of compromise between reality, performance and visual
>>quality into FGFS. Most 3d objects have to be seen from a distance and
>>do not need high poly geometry at all; zero thickness surfaces are very
>>often used and are a very good solution for building lowpoly objects
>>with double sided visible geometry.
>
>
> I guess I am not as willing as you are to make compromises. I really
> don't find rendering the edges of thin objects in scenery (so that they
> can be seen from all angles) to be a big deal.
Most of the objects you see into a FGFS scenery are buildings with
really few thin parts. I consider using full volume objects when needed,
but that's not the most common scenario.
Anyway I was talking about things like fences (especially when seen from
a distance) whose thickness is really irrelevant, and you see the
thickness when yhen you are really close to them only. In most cases,
objects like these can be rendered using simple double sided textured
planes, without any thickness at all. No UV map consistency struggle, no
need for high poly, maximum rendering performance, low GPU memory footprint.
>>That is something Blender developers should face one day or another.
>>Blender is going to grow every day more, it has to cope with a wide
>>variety of modellers' needs; it has to be flexible with respect to that,
>>otherwise it will stop being used, even if it's free.
>
>
> I seriously doubt this. Don't forget that Blender isn't model building
> software, it's a computer animation package. It's a testament to how
> good the software is that people even use it at all for a purpose that
> it is not even meant for. Still, you are free to make models however you
> want. It's just that I have in the past made all the arguments that you
> are making right now, and I found that I had come to the wrong
> conclusions because of inexperience.
>
> Josh
By the way, Josh you made your points clear.
The only way to go is to ask William to add a new option to his Blender
.ac exporter plugin and let the user decide if they want double sided to
be trashed away or not.
thanks Josh,
Roberto
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