Add mipmap calculation function

libs/gfx/include/psemek/gfx/texture.hpp

@@ -399,4 +399,20 @@ namespace psemek::gfx
 		: id_{0}
 	{}
 
+	template <std::size_t D>
+	std::size_t mipmap_count(geom::vector<std::size_t, D> const & size)
+	{
+		std::size_t s = 0;
+		for (std::size_t i = 0; i < D; ++i)
+			s = std::max(s, size[i]);
+
+		std::size_t result = 1;
+		while (s > 1)
+		{
+			s /= 2;
+			++result;
+		}
+		return result;
+	}
+
 }