[vox-tech] opengl: lines and points

[Ken Bloom]

On Sun, 30 Jan 2005 13:59:46 -0500
p at dirac.org (Peter Jay Salzman) wrote:

> On Sun 30 Jan 05,  9:58 AM, Ken Bloom <kabloom at ucdavis.edu> said:
> > On Sun, 30 Jan 2005 00:49:56 -0500
> > p at dirac.org (Peter Jay Salzman) wrote:
> > 
> > > Hola,
> > > 
> > > These are some really embarrassing questions, but I've been
> > > stumped for a while on this.
> > > 
> > > I've already written the requisite spinning cube.  I've even
> > > texture mapped it.  I've written a "flight simulator" that lets
> > > you fly around a teapot.
> > > 
> > > But there are 3 really basic questions I'm at a complete loss at.
> > > 
> > > 
> > > 1. The only point size that appears to be available is the default
> > > pointsize
> > >    of 1, whether I'm dealing with AA or not AA points.  I've
> > >    verified this with glGetFloatv() and GL_POINT_SIZE_RANGE.
> > > 
> > >    If there are any GL programmers out there, I'm curious what
> > >    point size ranges you have available on your system.
> > 
> > The GL_POINT_SIZE_RANGE on my nVidia Corporation NV18 [GeForce4 MX
> > 440 AGP 8x] is 0.000000 to 63.375000. This is probably
> > system-dependant.
> > 
> > What graphics card are you using?
>  
> Ken, I'm assumming that you actually ran a program like the one I
> posted to get your point size?  I'm really curious what Richard finds
> about his OpenGL point sizes.

I added a couple lines into your code to use glGetDoublev to read the
values of those properties, and printf them.

> I run a Voodoo-5 on the machine I'm having the wierd problems on.

There's a lot of OpenGL stuff that's dependant on the capabilities of
your graphics card, and this is one of them. (in fact, this is
true anywhere that you can ask OpenGL to tell you the minimum or maximum
value for a property)

You can use the properties GL_POINT_SIZE_RANGE and GL_LINE_WIDTH_RANGE
to find the values *your* graphics card supports.

> BTW, all my other machines seem to be posting a min and max point size
> of 1.0 too.   :-(
> 
> > > 2. Same problems with lines.  It appears that the only available
> > > width is
> > >    1.  I can make them thicker by drawing lines next to each
> > >    other, but the only width available on my system, both AA and
> > >    non-AA, is 1.  Again, I'm curious what other people have
> > >    available to them.
> > 
> > I don't know how to get this information.
>  
> I believe it's "GL_LINE_WIDTH_RANGE".

The OpenGL red book didn't document this. Thanks

0.500000 to 10.000000

--Ken Bloom
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