Re: [Flightgear-devel] Tree issues

[Vivian Meazza <vivian.meazza@li...>]

Stuart

> Sent: 19 May 2013 21:42
> To: FlightGear developers discussions
> Subject: Re: [Flightgear-devel] Tree issues
> 
> On Thu, May 16, 2013 at 11:02 PM, Vivian Meazza wrote:
> >> I'm going to have one more attempt to fix the black hat in a square
> > texture
> >> before looking into reducing the number of variations.
> >
> > Yup, works nicely here, there's definitely an improvement. I've also
> > modified the predicates for techniques 4 and 9 take that into account
> >
> > I've also fixed the black hat by increasing the bleed margins in
> > treebin.cxx a tad:
> >
> >         t->push_back(Vec2(variety + 1.0f, 0.234f));
> >         t->push_back(Vec2(variety, 0.234f));
> >
> > I'm using the old square texture - that would need adjusting because
> > those margins clip the top of the higher trees.
> >
> > All looking really good here now.
> 
> Thanks for the pointer.  I've committed a change using the reduced UV
> coordinates, converted all the tree textures back to squares and ensured
> they have an appropriate spacing at the top.
> 

That all looks very good here. No artefacts that I can see, no clipped
trees.  Job done for now, I would say.

Well Done

Vivian 

Re: [Flightgear-devel] Atmospheric Light Scattering during nighttime and the Sun

[Renk Thorsten <thorsten.i.renk@jy...>]

> By any chance, is this a bug when using atmospheric light scattering?

Yes. 

The issue you see is that real terrain is drawn out to some draw distance set by visibility and LOD range, and beyond what appears as fogged terrain is drawn by the skydome code. And the sun is set to be always visible on the skydome - so it becomes visible through skydome posing as terrain. I'm not quite sure, the same issue should also appear in the default rendering scheme then, although the colors are less dramatic, the default scheme retains a lot more red light for the sun below the horizon.

The problem is that the sun (moon,...) code is outside ALS and doesn't seem to run via a shader, so I can't fix it. A related issue is the sun shining through overcast sky (fog becomes so dense that the clouds are faded, in essence looking up you see the skydome drawn in grey, and the sun is never fogged.

The sun rendering would have to be made to respect the angle with the horizon and some fogging settings better in order to address this properly. A cheap 'fix', as you realized, is to draw terrain further out.

* Thorsten