Forcing hardware accelerated rendering

Question

I have an OpenGL library written in c++ that is used from a C# application using C++/CLI adapters. My problem is that if the application is used on laptops with Nvidia Optimus technology the application will not use the hardware acceleration and fail.

I have tried to use the info found in Nvidias document http://developer.download.nvidia.com/devzone/devcenter/gamegraphics/files/OptimusRenderingPolicies.pdf about linking libs to my C++-dll and exporting NvOptimusEnablement from my OpenGL-library but that fails. I guess I have to do something with the .exe not with the .dlls linked to the .exe

For us it is not a good option to use profiles since we need to ensure that the nvidia hardware is used.

Is there some way a C# application can force Optimus to use the Nvidia chipset instead of the integrated Intel chipset?

Answer 1

A working solution. Actually all those already mentioned, but it took me a time to understand how to get it work...

[System.Runtime.InteropServices.DllImport("nvapi64.dll", EntryPoint = "fake")]
static extern int LoadNvApi64();

[System.Runtime.InteropServices.DllImport("nvapi.dll", EntryPoint = "fake")]
static extern int LoadNvApi32();

private void InitializeDedicatedGraphics()
{
    try
    {
        if (Environment.Is64BitProcess)
            LoadNvApi64();
        else
            LoadNvApi32();
    }
    catch { } // will always fail since 'fake' entry point doesn't exists
}

Important - call InitializeDedicatedGraphics() before any window is created

Answer 2

I tried both options from the swine, but neither worked by themselves. I found I needed to attempt to call the imported function.

using System.Runtime.InteropServices;

class OptimusEnabler
{
    [DllImport("nvapi.dll")]
    public static extern int NvAPI_Initialize();
};

then in my app startup:

try
{
    ///Ignore any System.EntryPointNotFoundException
    ///or System.DllNotFoundException exceptions here
    OptimusEnabler.NvAPI_Initialize();
}
catch
{ }

On an nVidia Optimus system, I am getting a System.EntryPointNotFoundException, but it still works to make the application use the nVidia hardware. Tested on a system with an ATI card, I got a System.DllNotFoundException. Either way, attempting to call this and ignoring any exception here seems to work fine.