dash lines in pbuffer

OpenGL OpenGL: Advanced Coding
1

hi,

I’m struggling against a strange problem with pbuffers.
My pbuffer used with RGBA or Z is polluted by some kind of empty dash-dot lines (??!!)

I mean i fill my pbuffer with a Z or RGBA, and Some pixels are not filled and remain empty. don’t understand why !?

If I switch to use a framebuffer (or zbuffer) instead of pbuffer, the problem disapear.

here’s a picture (hope it works)
blue is the clear color, other is my pbuffer partially filled.

My card is geforce 4 ti 4600.

2

The above link would help if you also gave us access to your F: drive.

3

so here’s the picture.
now you will understand what I mean
dash in pbuffer

thanks

4

Looks like an enlarged polygon stipple pattern. Is polygon stipple enabled?
For more insights you need to show the code which sets up the pbuffer and draws into it.

5

thx relic,
yep, if I disable the polygon stipple my pb does not occur any more.

That’s strange, cause when I render directly in framebuffer the stipple does not appear.
And in Pbuffer the stipple sometime appears and disappears. depends where I am in the 3d scene. strange , isn’t it ?!

anyway thx for your help
now I can move forward.

6

That’s simple to figure out if you have all the code doing OpenGL rendering under you control:
Polygon stipple is off and the pattern is solid per default.
Do a search for GL_POLYGON_STIPPLE and glPolygonStipple in the code. It must be set and enabled somewhere.
If there’s a mismatch between the enables and disables in the pbuffer case, fix it.
If not, search for all glPush- and glPopAttrib to see if there’s a mismatch and fix it.
If not, things get difficult. Maybe render contexts not current, or driver bug.
However, fine that it works now.