{ config, pkgs, ... }:
{
###### intel igpu ########

hardware.opengl.enable = true;
#hardware.opengl.extraPackages = [ pkgs.mesa.drivers ];  
#hardware.opengl.extraPackages = [ pkgs.vaapiVdpau ];  

hardware.opengl.extraPackages = with pkgs; [
  intel-media-driver
  vaapiVdpau
  libvdpau-va-gl
];

#hardware.nvidia.nvidiaSettings = false;
#hardware.nvidia.modesetting.enable = true;  
#hardware.nvidia.package = config.boot.kernelPackages.nvidiaPackages.stable;

hardware.nvidia = {

  # Modesetting is required.
  modesetting.enable = true;

  # Nvidia power management. Experimental, and can cause sleep/suspend to fail.
  # Enable this if you have graphical corruption issues or application crashes after waking
  # up from sleep. This fixes it by saving the entire VRAM memory to /tmp/ instead 
  # of just the bare essentials.
  powerManagement.enable = false;

  # Fine-grained power management. Turns off GPU when not in use.
  # Experimental and only works on modern Nvidia GPUs (Turing or newer).
  powerManagement.finegrained = false;

  # Use the NVidia open source kernel module (not to be confused with the
  # independent third-party "nouveau" open source driver).
  # Support is limited to the Turing and later architectures. Full list of 
  # supported GPUs is at: 
  # https://github.com/NVIDIA/open-gpu-kernel-modules#compatible-gpus 
  # Only available from driver 515.43.04+
  # Currently alpha-quality/buggy, so false is currently the recommended setting.
  open = false;

  # Enable the Nvidia settings menu,
      # accessible via `nvidia-settings`.
  nvidiaSettings = true;

  # Optionally, you may need to select the appropriate driver version for your specific GPU.
  package = config.boot.kernelPackages.nvidiaPackages.stable;
};

##### nvidia offloading ########

 services.xserver.videoDrivers = [ "nvidia" ];

  hardware.nvidia.prime = {
    #sync.enable = true;
    offload = {
      enable = true;
      enableOffloadCmd = true;
      };
    
    # Bus ID of the NVIDIA GPU. You can find it using lspci, either under 3D or VGA
    nvidiaBusId = "PCI:1:0:0";

    # Bus ID of the Intel GPU. You can find it using lspci, either under 3D or VGA
    intelBusId = "PCI:0:2:0";
  };
}