delphi_fmx_3d_to_screen_func.pas

{ Obtains device scaling }
function GetScreenScale: Single;
var
   ScreenService: IFMXScreenService;
begin
   Result := 1;
   if TPlatformServices.Current.SupportsPlatformService (IFMXScreenService, IInterface(ScreenService)) then
   begin
      Result := ScreenService.GetScreenScale;
   end;
end;

{ Calculates position and applys screen scaling of devices if necessary }
function CalculateScreenPosition(Context: TContext3D; Point: TPoint3D; Scale: TPoint3D; Rotation: TPoint3D; Translation: TPoint3D; ApplyScreenScale: Boolean = False): TPoint3D;
var
  Tmpsp: TPoint3D;
begin
  Tmpsp := TPoint3D.Zero;
  Tmpsp := Point;
  Tmpsp := Tmpsp * TMatrix3D.CreateScaling(Scale);
  Tmpsp := Tmpsp * TMatrix3D.CreateRotationX(DegToRad(Rotation.X));
  Tmpsp := Tmpsp * TMatrix3D.CreateRotationY(DegToRad(Rotation.Y));
  Tmpsp := Tmpsp * TMatrix3D.CreateRotationZ(DegToRad(Rotation.Z));
  Tmpsp := Tmpsp * TMatrix3D.CreateTranslation(Translation);
  Tmpsp := Context.WorldToScreen(TProjection.Camera,Tmpsp);
  if ApplyScreenScale then begin
    Tmpsp := Tmpsp / GetScreenScale;
  end;
  Result := Tmpsp;
end;