fungus wrote:
> On Aug 22, 8:30=C2=A0pm, Flark <flark...@[EMAIL PROTECTED]
> wrote:
>> Hi,
>>
>> Suppose I want to show a model twice, but I want
>> the 2nd view of it to be in a smaller window tucked into
>> the corner of the main OpenGL window
>>
>> Is there a standard way to achieve this?
>=20
> It's tricky - OpenGL can zoom images but I don't think
> you can shrink them. Hardware to shrink images would
> be quite complicated.
I beg to differ. The filtering function required for shrinking
can be described in terms of a convolution. And convolutions can
be implemented quite efficiently using shaders. Once filtered
you just have to subsample.
> You could render it to a texture and draw quads for each
> size but the small image would only have GL_NEAREST
> filtering and would probably look horrible (though full screen
> antialiasing would help with this).
You can also do GL_LINEAR minification filtering w/o having
mipmaps. Although aliasing/moire artifacts may appear.
=20
> There's an extension to generate mipmaps for a texture
> in hardware but it won't work for non-power-of-two textures
> and I'm not sure that many cards sup****t it anyway.
>=20
> http://www.opengl.org/registry/specs/SGIS/generate_mipmap.txt
The extension has been around for some time and even my good old
GeForce2 can do it. It's no suprise though: You need
generate_mipmap for all kinds of render to texture stuff,
otherwise things would look horrible.
> PS: What happened to www.delphi3d.net ? I used to use
> it all the time to check which cards sup****ted OpenGL
> extensions but it's been broken for months.
>=20
> Are there any other web sites with lists of cards/extensions?
Not that I'm aware of, but I could start such a database, if
there's a wide interest.
Wolfgang Draxinger
--=20
E-Mail address works, Jabber: hexarith@[EMAIL PROTECTED]
ICQ: 134682867
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