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Cathedral

In this chapter you'll learn how to create a lamina from a wire, manipulate and edit wire segments, use multiple extrude, and mirror large sections of a building.

In this Chapter

You'll learn about the following techniques and commands:

Using the sketch editor and building a lamina

Flatten

Mirror

Merge Region

Multiple Extrude

Sketching the Wire

A lamina is a flat, two-sided polygon which can have any number of edges.

To build a lamina, you first sketch a wire to define the contour (perimeter) of the lamina, then make a polyhedron based on that wire's shape.

1. (CLICK-L) on GeoMenus>File>New Object>Lamina.

We call the process of drawing wires "sketching " or "encoding." N-Geometry has a special sketch editor devoted just to drawing wires. Before you begin sketching, however, you need to specify your sketching parameters in the dialog box that appears:

Figure 9.1 Setting your sketch parameters

Each of these parameters is described in detail in the N-Geometry Reference Guide. For now, change the following parameters:

2. (CLICK-M) on Mouse Grid (x).

Enter a new value of 1 and press RETURN.
Repeat the process for (y) and (z)

This constrains wire segments to a 1-unit grid in all three directions.

Figure 9.2 Change the grid parameters

3. (CLICK-L) on the Set Sketch Parameters button.

The Sketch Editor opens in the N-Geometry window. The target shape for the wire is shown in Figure 9.3:

Figure 9.3 The finished wire-refer back here if you need to

4. Move the cursor straight up the Y axis and (CLICK-L) to start encoding the wire.

Drag the mouse, then (CLICK-L) at each point until you've created the overhang for the top level roof. The distance between points 2-3, 3-4, and 4-5 should be one grid unit:

Figure 9.4 Starting the wire

Part of planning out a good lamina is determining where you should add segments for later. Under the roof's overhang, make three one-unit segments-later, we'll bridge through the middle segment to make some windows in our structure.

5. Add two more one-unit segments going straight down.

then repeat the entire process to create both levels of the roof.

Figure 9.5 Adding another roof

Starting an Arc

6. Now, (ALT-L) and move the mouse straight down.

As you move the mouse, a circle appears, using the segment from the last sketched point to the cursor's current position as the radius.
We're interested in the portion of the circle's edge, or arc, that leads from the last sketched point.

Figure 9.6 Defining the arc

7. (CLICK-L) when the arc is the right size.

8. Now, drag the mouse and (CLICK-L) at the point along the circle that you want drawn.

Figure 9.7 Completing the arc

The finished arc should look like this:

Figure 9.8 Completed arc

Now start the bottom of the cloister:

9. (CLICK-L) and drag one unit to the right, then (CLICK-L) again.

Figure 9.9 Start of the cloister

10. Now, (ALT-L) to start a new arc.

Drag the mouse right one unit, creating a preview of a two-unit circle:

Figure 9.10 Preview the circle

11. (CLICK-L) to define the arc, then continue to drag to the left. (CLICK-L) at the point of the circle straight across from where you started:

Figure 9.11 Use the arc tool to create a semi-circle

Now, using the skills you've learned so far, continue sketching the wire until it looks like that in Figure 9.12:

Figure 9.12 Adding a vertex here will let us extrude a column later on

Make sure that the vertical portions are divided into three one-unit segments so that we can bridge through them properly when the lamina's been extruded.

Figure 9.13

12. Now, (ALT-L) to start our last arc.

Drag the mouse right one unit and (CLICK-L), then drag up one unit to complete the arc.

Figure 9.14 Defining the final arc

13. (CLICK-L) to complete the arc.

Figure 9.15 The completed sketch

If You Make a Mistake While Sketching

To undo the last segment that you sketched, (SHIFT-L) on the sketch editor This undoes the previous segment on the wire-you can undo all the way back to the beginning of the wire.

14. (CLICK-R) when you are finished.

The following menu is displayed:

Figure 9.16 Choose Wire Only

15. Enter a name like "cathedral" for the wire in the dialog box that appears:

Figure 9.17 Name the wire

Fixing the Wire

Now when you look at the wire, you can probably see how we're going to use it. It looks like the side view of a cathedral that was cut right down the middle along the z-axis.

Later, we'll use the mirror command to create the "right" half of the cathedral, but to do so, we need to ensure that the face we're going to mirror from is perpendicular to the ground.

Look at the top of the wire:

Figure 9.18 Adjusting the wire to build a good lamina

Note that the two ends of the wire are not aligned. Since this section of the wire will create the face that we're going to "mirror" on, they need to be aligned:

16. (CLICK-L) on points on the element sensitivity menu.

17. (SHIFT-L) on the point at the top of the arc:

Figure 9.19 Choose the vertex you want to align

18. (CLICK-L) on Flatten.

Flatten "aligns" the selected element (in this case a point) with some other element, along a specified axis. In this case we want to move the selected vertex so that it lines up with the vertex that starts the lamina along the X axis.
When you use Flatten, you're prompted to first specify the axis for the operation:

Figure 9.20 Choose the axis for the flatten operation

19. (CLICK-L) on X.

Now, when you move the cursor over the N-Geometry window, you're in point-select mode.

20. (CLICK-L) on the node at the beginning of the wire:

Figure 9.21 Align the vertex using the vertex indicated

The lower node is "flattened" so that it lies in the same X plane as the target point:

Figure 9.22 Adjusting the wire to build a good lamina

Making the Lamina

Now you have the wire from which to create your lamina. A lamina is a two sided ("flat") polygon that uses the contour of the wire as an outline to describe its shape.

21. (CLICK-L) on GeoMenus>File>New Object.

22. This time, (CLICK-R) on Lamina.

If you (CLICK-L) you get sent to the sketch editor; (CLICK-R) lets you make a lamina from a wire you've already sketched.

23. Choose the wire "cathedral" from the object list that appears.

Figure 9.23 Choose the wire you created in step 15

24. A dialog box appears, asking for additional parameters to be used in creating the lamina.

Figure 9.24 Name the wire

For now, use the defaults and (CLICK-L) on the Make Lamina button.
The lamina is created and given the name "Lamina."

25. (CLICK-L) on GeoMenus>Visibility>Lamina.

This makes the Lamina the only visible object in the scene. (CLICK-L) on the front face to select it:

Figure 9.25 The completed lamina

Building the Cathedral

Now we can get down to business. We can build the cathedral using some of the same techniques we used in building the mansion earlier, plus some new techniques.

26. (CLICK-L) on faces on the element sensitivity menu.

27. (SHIFT-L) on the front face of the lamina, then (CLICK-L) on Extrude.

Extrude the face out so your object looks like this:

Figure 9.26 Extrude the face

Now, move the camera so that you're looking at the bottom and right sides of the lamina:

Figure 9.27 Reaping the benefits of planning

Reposition the camera again, so that can see the faces along the bottom of the object.

28. Collect the following faces:

Figure 9.28 Collecting faces where we want to add columns

29. (SHIFT-L) on the collection, then (CLICK-L) on Inset.

Specify an Inset Width of 0.2.

Figure 9.29 Inset the faces

30. (CLICK-L) on the Inset button.

The faces are inset by the specified amount:

Figure 9.30 Inset faces

31. (SHIFT-L) on the collection, then (CLICK-L) on Extrude.

Extrude the faces slightly downward and (CLICK-L).

Figure 9.31 Extrude the faces

Now, since we want all the columns to "line up" with our ground plane, let's use the Flatten command again.

32. (SHIFT-L) on the collection, then (CLICK-L) on Flatten.

33. When prompted, choose the Y axis.

Like before, N-Geometry goes into point select mode. (CLICK-L) on a point at the base of the main column:

Figure 9.32 Extrude the faces

The columns "flatten" along the Y axis to the main column:

Figure 9.33 The columns are now aligned

The Advanced Cathedral

Here are some optional additions you can make to your cathedral.

51. (CLICK-L) on faces on the elements sensitivity menu.

52. (SHIFT-L) on the face at the end of the hall, then (CLICK-L) on Multiple Extrude.

The following dialog box appears:

Figure 9.46 The Multiple Extrude dialog box

The Multiple Extrude operation lets you extrude a face one or more times, optionally combining other operations on the face with each iteration. This operation is described in more detail in a later tutorial.

53. (CLICK-L) on Add.

54. (CLICK-L) on Extend.

Enter a value of 50 in the dist text edit box.

55. (CLICK-L) on Add again.

56. (CLICK-L) on Rotate.

Enter a value of 45 in the angle text edit box.

Figure 9.47 Extruding and rotating with the Multiple Extrude operation

57. Leave the rest of the parameters at their default value and (CLICK-L) on the Extrude button.

The selected face is extruded and rotated:

Figure 9.48 The extruded face

58. (CLICK-L) on bodies on the element sensitivity menu.

59. (SHIFT-L) on the cathedral, then (CLICK-L) on Mirror.

60. Again, (CLICK-L) on the face at the end of the object.

Figure 9.49 The completed cathedral

For a final view, you might want to turn shading for the object back on:

Figure 9.50 The completed cathedral, shaded

You might want to use some of the skills you've learned so far to pull up towers, add doors, and so forth, to the cathedral.

Congratulations

You've now completed a fairly complex structure starting with a single well-planned wire. The techniques you learned in this chapter can be used in creating any object with an irregular contour, whether it be a building or a shard of glass.

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