Jim Wilson wrote:

> Frederic Bouvier said:
> 
> > Jim Wilson wrote:
> > 
> > > We first ran into this problem with the old back to front scheme when
> > David
> > > did the first trees. But I'm wondering now why the prop disks are a
> > problem.
> > > Shouldn't the aircraft model be on the bottom of the stack anyway?
> > Generally
> > > there's nothing between it and the camera.
> > 
> > The plane is in the same scenegraph than the terrain or other objects,
> > except
> > clouds. You have to draw them either before ( with terrain clipped or no
> > clouds
> > between the viewer and the terrain ), or after ( with prop disc problem ),
> > or
> > both like in the current situation.
> > 
> 
> We could do it in a separate sg, the only issue would be noticed taxiing
> behind a building, etc. With the triple rendering option it might be good to
> do the ac model that way in the default rendering mode. I don't know, maybe
> it is better to just deselect the transparent aircraft components in the
> external view.

In fact, I already render the scene 3 times, but for different objects :
 * 1st time, only terrain (OBJECT_BASE and OBJECT kind of scene objects ).
  To do that, I added a cull callback that returns the value of a boolean.
 * 2nd time, only 3d models except the aircraft ( another cull callback )
 * 3rd time the aircraft ( using the already existing ssgSelector )

in between, I draw clouds layers with depth update disabled ( but with depth
test enabled ). Thinking mode about it, I will test if I can remove one pass of 
cloud rendering. It will become :

 0. draw sky without clouds.
 1. draw terrain ( depth test, depth updated )
 2. draw all clouds ( depth test, no depth update )
 3. draw static objects ( stencil buffer updated with 1, depth test and depth updated )
 4. draw all clouds ( depth test, stencil test, no depth update )
 5. draw the aircraft.

That way, all semi transparent surface from objects or main aircraft will appear 
correctly without the need to discard them

Cheers,
-Fred


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