Draw Controller - Version 0

DrawControllerV0.cs

public class DrawController : MonoBehaviour
{
    public DrawRectangle RectanglePrefab;

    private readonly List<DrawRectangle> _allShapes = new List<DrawRectangle>();

    private DrawRectangle CurrentShapeToDraw { get; set; }
    private bool IsDrawingShape { get; set; }

    private void Update()
    {
        var mousePos = (Vector2) Camera.main.ScreenToWorldPoint(Input.mousePosition);

        var click = Input.GetKeyUp(KeyCode.Mouse0);
        var canUpdateShape = CurrentShapeToDraw != null && IsDrawingShape;
		
        if (click) {
            AddShapeVertex(mousePos);
        } else if (canUpdateShape) {
            UpdateShapeVertex(mousePos);
        }
    }

    /// <summary>
    /// Adds a new vertex to the current shape at the given position, 
    /// or creates a new shape if it doesn't exist
    /// </summary>
    private void AddShapeVertex(Vector2 position)
    {
        if (CurrentShapeToDraw == null) {
            // No current shape -> instantiate a new shape and add two vertices:
            // one for the initial position, and the other for the current cursor
            var prefab = RectanglePrefab;
            CurrentShapeToDraw = Instantiate(prefab);
            CurrentShapeToDraw.name = "Shape " + _allShapes.Count;
				
            CurrentShapeToDraw.AddVertex(position);
            CurrentShapeToDraw.AddVertex(position);
			
            IsDrawingShape = true;
				
            _allShapes.Add(CurrentShapeToDraw);
        } else {
            // Current shape exists -> add vertex if finished and reset reference
            IsDrawingShape = !CurrentShapeToDraw.ShapeFinished;

            if (IsDrawingShape) {
                CurrentShapeToDraw.AddVertex(position);
            } else {
                CurrentShapeToDraw = null;
            }
        }
    }

    /// <summary>
    /// Updates the current shape's latest vertex position to allow
    /// a shape to be updated with the mouse cursor and redrawn
    /// </summary>
    private void UpdateShapeVertex(Vector2 position)
    {
        if (CurrentShapeToDraw == null) {
            return;
        }
		
        CurrentShapeToDraw.UpdateShape(position);
    }
}