const
  GL_GPU_MEM_INFO_TOTAL_AVAILABLE_MEM_NVX = $9048;
  GL_GPU_MEM_INFO_CURRENT_AVAILABLE_MEM_NVX = $9049;

function GetTotalGraphicsMemory: Integer;
var
  i: GLInt;
begin
 i:=0;
 glGetIntegerV(GL_GPU_MEM_INFO_TOTAL_AVAILABLE_MEM_NVX, @i);
 result:=i;
end;

function GetCurrentGraphicsMemory: Integer;
var
  i: GLInt;
begin
 i:=0;
 glGetIntegerV(GL_GPU_MEM_INFO_CURRENT_AVAILABLE_MEM_NVX, @i);
 result:=i;
end;