Support setting program uniform by location

libs/gfx/include/psemek/gfx/program.hpp

@@ -112,6 +112,7 @@ namespace psemek::gfx
 		};
 
 		uniform_proxy operator[] (std::string_view name) const;
+		uniform_proxy operator[] (GLint location) const;
 
 	private:
 		GLuint program_;

libs/gfx/source/program.cpp

@@ -382,4 +382,9 @@ namespace psemek::gfx
 		return {location(name)};
 	}
 
+	program::uniform_proxy program::operator[] (GLint location) const
+	{
+		return {location};
+	}
+
 }