Making a custom selection box with DrawRect

Questions & Answers
1

I call the following during OnSceneGui in my custom editor to draw a custom selection box. Everything works as it should, as far as the debugger tells me - the proportions and position of the rectangle are correct, and are adjusted as you’d expect when the mouse moves, but the rectangle will not draw. What am I getting wrong?

Rect boundingRect = new Rect(0,0,0,0);

    void CheckForBoundingBox()
        {
            Event e = Event.current;
            HandleUtility.AddDefaultControl( GUIUtility.GetControlID( FocusType.Passive ) );
    
            if( e.button == 0 )
            {
                if( boundingRect.min != Vector2.zero )
                {
                    boundingRect.size = e.mousePosition - boundingRect.min;
                    EditorGUI.DrawRect( boundingRect, Color.red );
                    Debug.Log( "Dragging continues "+boundingRect );
                }
                if( e.type == EventType.MouseUp )
                {
                    e.Use();
                    Debug.Log( "Dragging stopped" );
                    boundingRect.min = Vector2.zero;
                }
                else if( e.type == EventType.MouseDown )
                {
                    e.Use();
                    boundingRect.min = e.mousePosition;
                    boundingRect.size = Vector2.zero;
                    Debug.Log( "Dragging started" );
                }
            }
        }
2

This is a solution to my problem, not an answer to my question, but instead of EditorGUI.DrawRect I used Handles. There might be something wrong with this solution, but it works. Here’s that part as it stands now:

if( boundingRect.min != Vector2.zero && e.type == EventType.Repaint )
{
    boundingRect.size = e.mousePosition - boundingRect.min;
    Ray ray = HandleUtility.GUIPointToWorldRay( boundingRect.min );
    Vector3 posA = ray.origin + ray.direction;
    ray = HandleUtility.GUIPointToWorldRay( boundingRect.min + (boundingRect.width*Vector2.right) );
    Vector3 posB = ray.origin + ray.direction;
    ray = HandleUtility.GUIPointToWorldRay( boundingRect.max );
    Vector3 posC = ray.origin + ray.direction;
    ray = HandleUtility.GUIPointToWorldRay( boundingRect.min + (boundingRect.height*Vector2.up) );
    Vector3 posD = ray.origin + ray.direction;
    Handles.DrawDottedLine( posA, posB, 5 );
    Handles.DrawDottedLine( posB, posC, 5 );
    Handles.DrawDottedLine( posC, posD, 5 );
    Handles.DrawDottedLine( posD, posA, 5 );
    Debug.Log( "Dragging continues "+boundingRect );
}