[gameprogrammer] Re: Sky in OpenGL

when you draw the whole sky, you could also skip glClear() which is nice

On 11/17/05, Sami Näätänen <sn.ml@xxxxxxxxxxxx> wrote:
> On Wednesday 16 November 2005 10:30, Alan Wolfe wrote:
> > make the sphere smaller then, the result should be the same :P
> >
> > have you tried that?
>
> One way would be to make the sphere so small that it fits in the clip
> region, but this has disavantage. You have to render the sky first
> without Z-buffer writes, which means multiple drawing of pixels. But
> one can draw the sky and then do some calculations etc before rendering
> the rest of the scene, so this might be in fact good solution.
>
> Other one is to use larger cliparea for the sky sphere.
>
> The best solution of course depends from the goals of the game.
>
> > On 11/16/05, Stephen <gp@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> > > Sorry, I spoke too soon - it doesn't work for me, but probably cos
> > > I'm doing something wrong.
> > >
> > > I'm setting up the openGL with this:
> > > glu.gluPerspective(45f, height_ratio, 0.1, 30f);
> > >
> > > Then I loop through all the objects, which all draw okay, and then
> > > the sky:-
> > > gl.glDisable(GL.GL_DEPTH_TEST);
> > > glu.gluSphere(Canvas3D.quadratic, DIAMETER, 24, 24);
> > > gl.glEnable(GL.GL_DEPTH_TEST);
> > >
> > > If I increase the 30f in the perspective command, it draws the sky.
> > > But at the moment it doesn't, even with the disabling of the depth
> > > test. BTW, I'm using Java and JOGL. Any help much appreciated!
> > >
> > > Thanks in advance,
> > >
> > > Steve.
> > >
> > > Stephane Marchesin wrote:
> > > > Stephen wrote:
> > > >> I'm having trouble working out what to do about how I implement
> > > >> a sky in my OpenGL game. I originally surrounded the game world
> > > >> with a massive sphere, and drew the image onto the inside, and
> > > >> it worked well (especially when I rotated it). However, I've now
> > > >> set the maximum view distance to be something more sensible, so
> > > >> OpenGL doesn't try to draw everything in the distance. However,
> > > >> this obviously means that the sky sphere now doesn't get drawn.
> > > >> How do other games get round this? I can't think of another way
> > > >> that would still produce a realistic looking sky.
> > > >
> > > > glDisable(GL_DEPTH_TEST);
> > > > render_sky();
> > > > glEnable(GL_DEPTH_TEST);
> > > >
> > > > Stephane
> > > >
> > > >
> > > >
> > > >
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