Event-driven Graphics Mode

Before we begin the next part of the exercise, it is necessary to understand how to use the cursor to pick points in the graphical view. Whenever the status line immediately below the menu bar of the 3D View shows a prompt other than ’Navigate’, as now, the graphical view is switched automatically into event-driven graphics mode. This means that when you pick a point in the displayed graphics, your action is interpreted in whatever way is appropriate to your current design operation (that means, the current event) rather than simply as a request to navigate to a new current element. In this example, picking in event-driven graphics mode will be used to specify a position.

The position derived from your cursor pick can be the exact point at which you have placed the cursor or, more commonly, it can be a position which is related to the picked point in a specified way. The main concept involved in structural applications is that of the snap function, which automatically chooses the nearest Start, End or (optionally) Secondary Node position to the picked point, so that you do not need to be very accurate when positioning the cursor.

The full range of options available for identifying positions is extensive. We will use it in the exercise simply to pick a p-point which is already at the required position.

Exercise continues:

1. The current position of the design template origin, relative to the template geometry, is at the center of the box, as shown by the Template Origin label which you will now see in the 3D View (rotate the view if necessary to see the position properly; the label may be difficult to read because the equipment origin is labelled at the same location).

2. In order to provide a more convenient datum point for positioning the kickplate assembly relative to the surface of a panel, we will redefine the origin as being at the center of the lower face of the box.

   To do so, we will enter the Origin data on the Create Template form by picking an existing p-point at the required position. We are already in event-driven graphics mode (as shown by the 3D View status line which says ‘Defining a Template Snap’).

3. On the Positioning Control form, set the Pick Type (left-hand box) to Ppoint and the Pick Method to Snap. This constrains the system to allow you to pick only p-points. Move the cursor into the 3D View, hold down the left-hand mouse button, and move the cursor over the box (click on any edge of the box if you are using a wireline view). The p-points appear as dots in the view and the cursor shape changes to when it is over a p-point. The name of the selected point is shown in the status line. Release the mouse button when the cursor is over P6 of BOX /Kickplate-Outer.

   Notice how the Origin coordinates are now shown in the Create Template form as Y 0, X 0, U 125 and how the labelling has changed in the new 3D View.

4. Leave the Add Properties and Add Points selected and OK the Create Template form. The Template Browser should now show the following elements:

   

   The 3D View will now show both the original equipment and the template derived from it (offset by the amount by which the origin has been repositioned). From the Template Browser, select Display to show just the current template in a new 3D view.