GL_MULTISAMPLE and textures
Anonimous Anonimous
I'm confused on the multisampling extension. I made an openGL context
through a QTGLWidget which has samplebuffers enabled, and set the
samplecount to 16 (also tried 4).
Some of the objects in my scene are anti-aliased fine. But if I just
draw a rectangular texture (GL_TEXTURE_RECTANGLE target, GL_RGBA), the
pixels of the rectangle are not anti-aliased. If I set the texture
object's filtering to GL_LINEAR, some AA is done, but my understanding
is that this filtering is different from the multisampling in that it
just enables smooth scaling of pixels.
GL_MULTISAMPLE is enabled, and I don't want to use mip-mapping because
the rectangle texture is written to a lot.
So my idea was that this extension enables a framebuffer that multi-
samples everything drawn in it, even pixels of a texture object. Am i
missing something here? Does the multisampling maybe only apply to
primitive edges? If so, how should I multisample the texture itself?
ciao,
C.
fungus
wrote:
> If I set the texture
> object's filtering to GL_LINEAR, some AA is done, but my understanding
> is that this filtering is different from the multisampling in that it
> just enables smooth scaling of pixels.
>
The two things are completely separate.
> GL_MULTISAMPLE is enabled, and I don't want to use mip-mapping because
> the rectangle texture is written to a lot.
>
So? Use the GL_SGIS_generate_mipmap extension and the
graphics card can make the mipmaps very efficiently.
> So my idea was that this extension enables a framebuffer that multi-
> samples everything drawn in it, even pixels of a texture object. Am i
> missing something here? Does the multisampling maybe only apply to
> primitive edges?
>
No, multisampling applies to all pixels.
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