added the basic requiements for physics with box2d

TSE_Core/src/elements/PhysicsEngine.cpp

@@ -0,0 +1,57 @@
+#include "PhysicsEngine.hpp"
+#include "utils/Time.hpp"
+
+void TSE::PhysicsEngine::InitPhysics(Vector2 gravity)
+{
+    b2WorldDef def = b2DefaultWorldDef();
+    def.enableSleep = true;
+    b2Vec2 grav;
+    grav.x = gravity.x;
+    grav.y = gravity.y;
+    def.gravity = grav;
+    worldId = b2CreateWorld(&def);
+}
+
+void TSE::PhysicsEngine::UpdatePhysics()
+{
+    if(elapsedTime >= timestep)
+    {
+        elapsedTime = 0;
+        b2World_Step(worldId, timestep, iterations);
+        //update physics objects
+    }
+    elapsedTime += Time::deltaTime();
+
+    for(auto obj : registeredObjects)
+    {
+        obj->UpdatePosition();
+    }
+}
+
+void TSE::PhysicsEngine::DeletePhysics()
+{
+    b2DestroyWorld(worldId);
+}
+
+void TSE::PhysicsEngine::RegisterPhysicsObject(PhysicsObject *obj)
+{
+    registeredObjects.push_back(obj);
+}
+
+void TSE::PhysicsEngine::UnRegisterPhysicsObject(PhysicsObject *obj)
+{
+    auto it = registeredObjects.begin();
+    for (; it != registeredObjects.end(); it++)
+    {
+        if(*it == obj)
+        {
+            registeredObjects.erase(it);
+            return;
+        }
+    }
+}
+
+b2WorldId &TSE::PhysicsEngine::GetWorldId()
+{
+    return worldId;
+}