Jim Wilson writes:
> Norman Vine said:
> > Jim Wilson writes:
> > > >
> > >
> > > As far as the reason the existing alpha-blend code doesn't work may be
> > > related
> > > to an update in 1.8.4 that was described in ChangeLog as "smaller and
> > > cleaner
> > > scene graphs". That's just a WAG, but it seems that this function would
> > > be
> > > better accomplished through an API rather than writing directly back to
> > > scenegraph memory from SimGear anyway (I find it mildly irritating that
> > > you
> > > can even do that :-/).
> > My guess is that you aren't following the rules :-)
> > http://www.opengl.org/resources/tutorials/advanced/advanced97/notes/node111.html
> You might be right. From the above link, it says: "If lighting is enabled,
> then the ambient and diffuse reflectance coefficients of the material should
> correspond to the translucency of the object." So does this mean that when
> using the plib API it is necessary to set alpha in both the ambient _and_
> diffuse state colors? I think I tried that but...
> ..for some reason I was seeing some bogus numbers (> 1.0 colors) come up for
> ambient when dumping the ssgLeaf objects concerned. Maybe finding the source
> of that problem will fix things.
I was alluding render ordering.
Note it could be that the 'optimization' code in ssgBranch.cxx is doing things
'behind your back' after loading that invalidates any assumptions about the
render order being the inverse of the loading order.
< not that you are necessarily making this assumption >
you are familiar with this
Flightgear-devel mailing list