Re: pfLayer polygons and the clipping plane
John Rohlf (jrohlf++at++tubes)
Thu, 18 May 95 17:50:44 PDT
>
> My loader uses pfLayer for the network (roads, rivers, etc.) polygons
> in the scene. The underlying terrain forms the base and the roads are
> decaled on top. Note the database is "tiled". The terrain and
> network polygons for each 1K tile are placed in a single pfLayer node
> for that tile. The network polygons are clipped to the tile boundary.
>
> I've noticed that the decaled polygons at the far clipping plane make
> the cull before the base layer. So when there is a hill in the
> distance coming into view with a road on it, first the roads stick up
> with no terrain underneath, then the terrain comes in. Is this a
> problem with bounding spheres? Do I need to force the bounding
> spheres of the base and decal layer geometry to be the same? Or is
> there something else going on here?
>
This is an artifact of the PFDECAL_BASE_DISPLACE method
for rendering layers. The displace mechanism brings the roads closer
to you so you see them before the ground. The only solution now is to use
the higher quality, but slower stencil mechanism:
pfLayerMode(layer, PFDECAL_BASE_STENCIL)
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on Mon Aug 10 1998 - 17:51:30 PDT