5 Microsoft Windows Specifics
5.010 What's a good source for Win32 OpenGL
programming information?
See Blaine Hodge's web page. Be aware that this page shows usage of the AUX library,
which is not recommended.
5.020 I'm looking for a Wintel OpenGL card in a
specific price range, any suggestions?
The consumer-level 3D graphics marketplace
moves fast. Any information placed in this FAQ would be soon
outdated.
You might post a query on this topic to the
comp.graphics.api.opengl newsgroup, or one of the many
newsgroups devoted to Wintel-based 3D games. You might also
do a Web search.
Tom's
Hardware Guide and Fast
Graphics have a lot of information
on current graphics cards.
5.030 How do I enable and disable hardware
rendering on a Wintel card?
Currently, OpenGL doesn't contain a switch
to enable or disable hardware acceleration. Some vendors
might provide this capability with an environment variable or
software switch.
If you install your graphics card, but don't
see hardware accelerated rendering check for the following:
- Did you install the device driver /
OpenGL Installable Client Driver (ICD)? (How do I do that?)
- Is your desktop in a supported color
depth? (Usually 16- and 32-bit color are accelerated.
See your device vendor for details.)
- Did your application select an
accelerated pixel format?
You might also have acceleration problems
if you're trying to set up a multimonitor configuration.
Hardware accelerated rendering might not be supported on all
(or any) devices in this configuration.
To temporarily disable hardware
acceleration, move or rename your OpenGL ICD. Also, check
your device's documentation to see if your device driver
supports disabling hardware acceleration by a dialog box.
5.040 How do I know my program is using hardware
acceleration on a Wintel card?
OpenGL doesn't provide a direct query to
determine hardware acceleration usage. However, this can
usually be inferred by using indirect methods.
If glGetString(GL_VENDOR) returns something
other than "Microsoft Corporation", then you are
using the board's ICD. If it returns "Microsoft
Corporation", normally this implies you chose a pixel
format that can't be accelerated by your device. However,
this is also returned if your device has an MCD instead of an
ICD, so you might still be hardware accelerated in this case.
Another way to check for hardware
acceleration is to temporarily remove or rename the ICD, so
it can't be loaded. If performance drops, you know that you
were hardware accelerated before. Don't forget to put the ICD
back the way it was.
You can also gather performance data by
rendering into the back buffer and comparing the results
against known performance statistics for your device. See the section on
performance for more information.
5.050 Where can I get the OpenGL ICD for a
Wintel card?
If your device supports OpenGL, the
manufacturer should provide an ICD (commonly referred to as
the device driver) for it. After you install the ICD, your
OpenGL application can use the device's hardware capabilities.
If your device didn't come with an ICD on
disk, you'll need to check the manufacturer's Web page to see
where you can download the latest drivers. The chip
manufacturer will probably have a more current ICD than the
board manufacturer. Find the device driver download page, get
the latest package for your device, and install it per the
instructions provided.
Check Reactor
Critical for nVidia device drivers.
They often have more current and better performing OpenGL
device drivers than nVidia makes available from their web
page.
GLsetup, a free utility, is available.
According to the GLsetup Web page, it "detects a
user's 3D graphics hardware and installs the correct device
drivers." You can get it from http://www.glsetup.com.
5.060 I'm using a Wintel card, and an OpenGL
feature doesn't seem to work. What's going on?
It could simply be a bug in your code.
However, if the same code works fine on another OpenGL
implementation, this implies the problem is in your graphics
device or its ICD. See the previous question for
information on obtaining the latest ICD for your device.
5.070 Can I use OpenGL with DirectDraw?
This won't work on some drivers, and is
therefore unportable. I don't recommended it.
5.080 Can I use use DirectDraw to change the
screen resolution or desktop pixel depth?
This probably depends on your graphics
device and what, if any, support for this type of operation
your device driver provides. You need to keep this basic
tenet in mind: Microsoft doesn't require, and consequently
does not test for, the ability to render OpenGL into a
DirectDraw surface. For this reason, you shouldn't expect
this window creation strategy to be available.
5.090 My card supports OpenGL, but I don't get
acceleration regardless of which pixel format I use.
Are you in 8bpp? There are few 3D
accelerators for PCs that support acceleration in 8bpp.
5.100 How do I get hardware acceleration?
The pixel format selects hardware
acceleration. Pay attention to the flags GENERIC_FORMAT
and GENERIC_ACCELERATED. You want both of them on if you're
using a 3D-DDI or an MCD and neither on if you are using an
ICD. You may have to iterate using DescribePixelFormat()
instead of only using ChoosePixelFormat().
5.110 Why doesn't OpenGL hardware acceleration
work with multiple monitors?
In Windows 98, Microsoft decided to disable
OpenGL hardware acceleration when multiple monitors are
enabled. In Windows NT 4.0, some drivers support
multiple monitors when using identical (or nearly identical)
cards. I don't believe multiple monitors and hardware
accelerated OpenGL work with different types of cards.
I don't know the story with Windows 2000, but it's likely to
be similar to Windows NT 4.0.
5.120 Why does my MFC window flash, even though
I'm using double buffering?
Your view class should have an
OnEraseBackground() event handler, which should do nothing
other than return TRUE. This tells Windows that you've
cleared the window. Of course, you didn't really clear the
window. However, returning TRUE keeps Microsoft from trying
to do it for you, and should prevent flashing.
5.130 What's the difference
between opengl.dll and opengl32.dll?
According to OpenGL Reference Manual
editor Dave Shreiner:
"Unless there's an absolutely
compelling reason … I really would suggest using opengl32.dll,
and letting the old opengl.dll thing die.
"opengl.dll comes from the now
totally unsupported OpenGL for Windows release of OpenGL
for Microsoft Windows by SGI. We stopped supporting
that release over two years -- like no one ever touches
the code. …
"Now, why use opengl32.dll?
For the most part, SGI provides Microsoft with the ICD
kit, sample drivers, and software OpenGL implementation
that you find there. Its really the same code base
(with fixes and new features) as the opengl.dll, its only
that we got Microsoft to ship and support it (in a manner
of speaking)."
More information on
linking with opengl.dll can be found here.
5.140 Should I use Direct3D or
OpenGL?
A good comparison of the two can be found here.
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