(NDK) Added Velocity component/system

Former-commit-id: 427b7175fbf9723fcd1d54fc279b8b70167745d4

SDK/src/NDK/Systems/VelocitySystem.cpp

@@ -0,0 +1,28 @@
+// Copyright (C) 2015 Jérôme Leclercq
+// This file is part of the "Nazara Development Kit"
+// For conditions of distribution and use, see copyright notice in Prerequesites.hpp
+
+#include <NDK/Systems/VelocitySystem.hpp>
+#include <NDK/Components/NodeComponent.hpp>
+#include <NDK/Components/VelocityComponent.hpp>
+
+namespace Ndk
+{
+	VelocitySystem::VelocitySystem()
+	{
+		Requires<NodeComponent, VelocityComponent>();
+	}
+
+	void VelocitySystem::Update(float elapsedTime)
+	{
+		for (const Ndk::EntityHandle& entity : GetEntities())
+		{
+			NodeComponent& node = entity->GetComponent<NodeComponent>();
+			const VelocityComponent& velocity = entity->GetComponent<VelocityComponent>();
+
+			node.Move(velocity.linearVelocity * elapsedTime);
+		}
+	}
+
+	SystemIndex VelocitySystem::systemIndex;
+}