Onboarding of new SEE members

[koschke]

New SEE members should familiarize themselves with the basics of the SEE implementation by solving a simple task that touches most relevant pieces of code.

A new marking action is to be implemented. A user should be able to select an element in a code city (an inner node or a leaf in terms of the underlying graph) to mark it. When marking a node, the following should happen (marking works as a toggle):

• When a node is not yet marked, it will be marked by showing a sphere above the selected node (developers can select any color). The diameter of the sphere must be the minimum of the width (x axis) and depth (z axis) of the marked node.
• When a node is already marked, the sphere created for the marking is destroyed.

Required implementations:

• A new class SEE.Controls.Actions.MarkAction must be added (note our coding guidelines: the directory structure must reflect the namespace and filenames must be chosen reflecting the main class contained therein; thus, the code of this new class must be contained in Assets/SEE/Controls/Actions/MarkAction.cs.) The new class must be derived from class AbstractPlayerAction. All required methods must be implemented (Update, Undo, Redo, CreateReversibleAction, NewInstance, GetActionStateType, GetChangedObjects). The duty of this class is to manage the user interaction and to provide undo/redo capabilities.
• A new class SEE.Net.MarkNetAction must be added. It must derive from SEE.Net.AbstractNetAction. Its purpose is to broadcast an action of the local player to all clients, that is, to replicate the action in all client code cities such that all players always have a consistent view of the SEE scenery.
• A new static class SEE.Game.SceneManipulation.GameNodeMarker must be added. Its purpose is to provide the necessary functions to create and destroy the sphere for the marking. Both SEE.Controls.Actions.MarkAction and SEE.Net.MarkNetAction must essentially do the same thing: mark a node visually by a sphere. SEE.Controls.Actions.MarkAction does this locally (for the player triggering this action) and SEE.Net.MarkNetAction does this remotely. To avoid duplicated code, the shared code for the marking/unmarking is factored out into this new class SEE.Game.SceneManipulation.GameNodeMarker.
• The action must be made available in the player menu (which can be turned on by the user by pressing the space bar). To add the new action to this user menu, the class SEE.Controls.Actions.ActionStateTypes must be extended by providing a new static property analogous to the other declarations in code region Static Types. This new static ActionStateType property must be returned by method SEE.Controls.Actions.MarkAction.GetActionStateType.

Hints:

• Take a look at the existing code for adding a node, namely, the classes SEE.Controls.Actions.AddNodeAction, SEE.Net.AddNodeNetAction, and SEE.Game.SceneManipulation.GameNodeAdder as an example.
• GameObjectExtensions.GetTop() yields the world-space center position of a game object taking into account the antenna or other kinds of decoration on top of a block.
• Consider the case that a game object is already marked. If so, it should be unmarked, that is, the added sphere should be removed again.