Lighting in opengl is not only specified by an abient and a diffuse component,
but also by an emission and a specular.
These four components are added together before rendering a primitive.
Emission ( which I think is enabled on the C172) is a color component
independet of any ambient or diffuse light setting. That's why it glows or
shines even at night. I am pretty sure that when you remove that component
the C172 will look ok.
The specular component is the reflection of the light on the surface.
You see this component only if you are looking to the surface and it's
reflection hits the sun.
I try do some ASCII arts to make clear:
sun viewpoint
\ /
\ /
\/
--------------------------- surface
Juergen
Am Sonntag, 21. Juli 2002 16:58 schrieb Frederic Bouvier:
>
> > Curtis L. Olson writes:
> > > However, the C172 still stays fully illuminated all the time, even in
> > > the dead of night. Futhermore it is not shaded at all during the day
> > > relative to sun position. So, I my theory at this point is that this
> > > model must have the emmissive property set???? so it is always fully
> > > self illuminating?
> >
> > The glow (as opposed to sun illumination) is the result of a different
> > and strange effect -- it depends on the non-textured rgb value of the
> > surface, even though the surface is textured. Set rgb in the *.ac
> > file to 1 1 1 (the default for many AC3D models exported from Blender)
> > and the model glows at night; set rgb to 0 0 0 and the model is always
> > black, even in the day time; set it to .5 .5 .5 and the model is
> > always grey, etc.
> >
> > But wait, there's more ...
> >
> > For reasons unknown, the effect is different depending on whether
> > you're inside or outside the plane. This is best illustrated by two
> > screenshots of the same buildings, one from inside view and one from
> > outside view:
> >
> > http://www.megginson.com/flightsim/inside-lighting.jpg
> >
> > http://www.megginson.com/flightsim/outside-lighting.jpg
> >
> > Notice that not only the plane starts to glow, but also the water
> > tower and most of the buildings. For some reason, the rgb colour gets
> > blended with the texture in external view (also in the two tower
> > views) but not in cockpit view.
>
> I have just noticed that too, but models I send you yesterday are not
> glowing. Compare small-glass-office-building and cube-apartment.
> The first glow and not the second in the external (chase) view.
> I think your textures are rgba while mine are only rgb. Going to verify
> that point.
>
> Wait... the tower-hexa only glow on certain faces and not on others.
> It's going strangers...
>
> Cheers,
>
> -Fred
>
>
>
>
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