More ill-informed ramblings...
Experimenting with DXDiag's Display tests plus RegMon from www.sysinternals.com it looks like you can read the Registry key "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Direct3D\Drivers\SoftwareOnly" (using the Win32 API's RegistryOpenKey and RegistryQueryValue functions) to determine whether you're in software mode or not (hardware 3D acceleration being available should give a value of 0, software 1). It can also be used to set the mode -- DXDiag updates in real time to reflect this when you edit the value in RegEdit; this is NOT a good idea, other than for testing on your own machine!
Fiddle at your own risk! Stick to only reading the key.
For OpenGL, I guess you could check to see if you can open "opengl32.dll" via LoadLibraryA if you want to be really careful, then open your display, and use this to try and determine whether it's accelerated: "5.040 How do I know my program is using hardware acceleration on a Wintel card?". Yikes. It doesn't seem like you can check with OpenGL until you have a display, or at least not via any official method.
Experimenting with DXDiag's Display tests plus RegMon from www.sysinternals.com it looks like you can read the Registry key "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Direct3D\Drivers\SoftwareOnly" (using the Win32 API's RegistryOpenKey and RegistryQueryValue functions) to determine whether you're in software mode or not (hardware 3D acceleration being available should give a value of 0, software 1). It can also be used to set the mode -- DXDiag updates in real time to reflect this when you edit the value in RegEdit; this is NOT a good idea, other than for testing on your own machine!
Fiddle at your own risk! Stick to only reading the key.
For OpenGL, I guess you could check to see if you can open "opengl32.dll" via LoadLibraryA if you want to be really careful, then open your display, and use this to try and determine whether it's accelerated: "5.040 How do I know my program is using hardware acceleration on a Wintel card?". Yikes. It doesn't seem like you can check with OpenGL until you have a display, or at least not via any official method.