View Full Version : Choosing a GL laptop

05-23-2002, 02:06 AM

I'm currently trying to get a demonstrator up together to demo a GL application that I've been developing. The powers that be decided that I should not have the nVidia GeForce2 spec machine that I asked for, and instead bought a Dell Latitude with a poxy ATI Mobility RADEON with 16MB DDR.

Am I right in thinking that the diabolical performance I'm seeing is down to the graphics adapter, i.e. CPU max'd out, really, really bad blending and unexpected artifacts in the rendered view? My desktop has a 32 meg GeForce2 and runs really nicely. The laptop CPU is about 1/2 a gig faster.

If it turns out that I can't get good graphics performance from any of the company's standard build rubbish, can anyone recommend a decent spec for a laptop that will give me usable performance?



05-23-2002, 04:22 AM
have a look at: http://www.tomshardware.com/mobile/02q1/020220/

The ati chip you have is currently the fastest mobile graphics chip - beating the geforce2 go chip by quite a margin. Chances are that you have chosen a pixel format etc that is dropping you into software rendering on the laptop but not on the geforce desktop machine. This is all I can think of at the moment.

05-23-2002, 05:15 AM
Sorry to be a pain. What you said sounds sensible. Do you know of a way to determine the hardware supported pixel formats before I set them?



05-23-2002, 05:57 AM
Use this code after you have set the pixel format:

PIXELFORMATDESCRIPTOR pfd_new;DescribePixelFormat (hDC, nPixelFormat, sizeof(PIXELFORMATDESCRIPTOR), &pfd_new);int generic_format = pfd_new.dwFlags & PFD_GENERIC_FORMAT;int generic_accelerated = pfd_new.dwFlags & PFD_GENERIC_ACCELERATED;if (generic_format && !generic_accelerated){ // software rendering}else if (generic_format && generic_accelerated){ // hardware rendering with MCD}else if (!generic_format && !generic_accelerated){ // hardware rendering with ICD}

this should let you find out if this is actually the problem. If you find that you are in software then keep changing the pixel format and re-trying. The more advanced solution would be to write some code that loops through all hardware pixel formats and chooses the closest one to the one you are requesting. I have not done this more advanced way yet so couldn't help you on this yet.

Well anyway, hope the above code helps.

05-23-2002, 05:59 AM
sorry - code didn't paste over very well, just split it after the semi-colons.

05-23-2002, 06:30 AM
Thanks for that snippet. It seems to work nicely. I'll go for the more advanced approach when I've worked out how to enumerate the pixel formats, seen an example somewhere, trying to find it....

Don't yet know however, if it really is the laptopn dropping into software rendering as it's behaving very strangely at the moment.

Thanks again