z-buffer error

lordcool · Post by **lordcool** » Wed Feb 21, 2007 3:36 pm

i draw a grass ploygon on a plane ground. but z-buffer error.
see this,
http://hompy.ollio.com/view.asp?fnm=hompy164071.jpg

tested gforce7900GT(with latest driver) winXP
irrlicht1.2 D3D9 and OPENGL

i need help.

datamagik · Post by **datamagik** » Fri Feb 23, 2007 7:38 am

Your jpg was not visible when i looked at your page.

Perhaps you might just upload the jpg instead of using the asp to show it?

Phant0m51 · Post by **Phant0m51** » Fri Feb 23, 2007 7:10 pm

Your problem is that you're drawing the grass polygon at the exact height that you're drawing the ground.

Try moving the grass polygon up.

lordcool · Post by **lordcool** » Sat Feb 24, 2007 2:20 pm

grass polygon height is high enough.
I found out this problem.
my program uses the high position values. it's higher than 2^24.
i guess the problem is 24bits z-buffer overflow.
i tested some ATI card and most NVidia card have this problem.
but some ATI Radeon card was fine.

this problem is existing the position value higher than 2^18.
and skybox shaked when camera moving.

because of 32bits depth buffer dosen't working both gl and d3dx.
i resolved this,
- position data recalculate lower values real time from DB when recieving often.

reply any suggestion if you have any good idea or info.