PhysicsManager now has a job, CollisionManager enabled, using Player velocity instead of position for movement controls, added Entity drag, added spaces

lib/managers/physics_manager.rb

@@ -10,9 +10,27 @@ class IMICFPS
           resolve(entity, other)
         end
       end
+
+      simulate
     end
 
     def resolve(entity, other)
+      if other.is_a?(Terrain)
+        entity.velocity.y = 0 if entity.velocity.y < 0
+      else
+        entity.velocity.y = other.velocity.y if other.velocity.y < entity.velocity.y && entity.velocity.y < 0
+      end
+    end
+
+    def simulate
+      @collision_manager.game_state.entities.each do |entity|
+        entity.velocity.x *= entity.drag
+        entity.velocity.z *= entity.drag
+
+        entity.position.x += entity.velocity.x * entity.delta_time
+        entity.position.y += entity.velocity.y * entity.delta_time
+        entity.position.z += entity.velocity.z * entity.delta_time
+      end
     end
   end
 end