/// <summary>
 /// System.Drawing.Color to C4d.
 /// </summary>
 public static C4d ToC4d(this Color color) => new C4d(
     Col.DoubleFromByte(color.R),
     Col.DoubleFromByte(color.G),
     Col.DoubleFromByte(color.B),
     Col.DoubleFromByte(color.A));
 /// <summary>
 /// System.Drawing.Color to C3d.
 /// </summary>
 public static C3d ToC3d(this Color color) => new C3d(
     Col.DoubleFromByte(color.R),
     Col.DoubleFromByte(color.G),
     Col.DoubleFromByte(color.B));