Magnet Operations

In this chapter you'll learn how to use N-Geometry's magnet operation technique to distribute the effect of a command over a selected area of a model.

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In this Chapter

• Magnet operations

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Building a Mountain Range

2. (CTRL-L) on Grid.

The following dialog box is displayed:

Note. Holding down the CTRL key when creating any primitive lets you specify additional parameters about how the primitive is created.

Additional parameters typically let you specify size, orientation, number of subdivisions in the object, and so forth.

3. Set the Orientation to Y and (CLICK-L) on the Make Grid button.

A grid appears in the N-Geometry window:

Figure 5.2 A simple grid, oriented along the Y plane

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Using Magnet Operations

4. (SHIFT-L) on a vertex near the corner of the grid.

This will be the "peak" of our first mountain:

5. (ALT-M) on Axis Move.

Hold down the ALT key when you (CLICK-L) on Axis Move.

Now, move the cursor over the grid again. You'll notice that as you move the cursor over the model, the vertex under the cursor is highlighted.

When the cursor is in this mode, you're being asked to select a point that defines the perimeter for the area of influence for the magnet move.

7. (CLICK-L) on a vertex two units away from your peak.

Figure 5.4 Choose a point a short distance from the "center" of the magnet move

This defines the area of influence for the move.

8. Move the mouse to the right.

The vertex at the center rises the most; those toward the edge are affected less and less the further they are from the original point selected:

Magnet Moves on Multiple Elements

Try this:

9. Collect several points on the grid that are somewhat separated from each other.

Figure 5.6 Select several vertices on the grid

10. (ALT-M) on Axis Move.

11. (CLICK-L) on Y to select the Y Axis.

12. (CLICK-L) on a vertex one square away from the peak closest to the upper right grid.

Figure 5.7 Select an area of influence

13. Move the mouse to the right and pull up several mountains.

Note that all the mountains are identical; the sphere of influence is based on the distance of the point selected in step 12 and the nearest selected element.

Note. The "sphere of influence" is calculated based on the defining vertex's distance from the closest selected element.

Figure 5.8 The sphere of influence is the same for each selected element

Note. This feature makes it easy to create features such as scales on a dragon (or other types of bumps across a wide surface) using a uniform area of influence.

If you want to have different areas of influence for different elements, you should select them independently.

Try pulling out several different mountains, using different areas of influence.

Performing Magnet Moves on Other
Element Types

Repeat steps 4 through 8, selecting a segment or face (instead of a vertex) in step 4.

Figure 5.9 A mountain range landscape with 101 polygons (1 on bottom!)

Which Commands?

Conceptually, the important thing to understand is that there is a falloff across the defined area. Some other example might produce results like those shown below.

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Making an Egg

Figure 5.10 Select the top face on the sphere

2. Select a point somewhere near the sphere's "equator" to set the area of influence.

3. Move the mouse to the right.

Figure 5.11 Magnet with Scale operation

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Creating a "Vacuum" Effect

Try this:

1. (SHIFT-L) on the face on top of the sphere.

2. (ALT-M) on Rotate>X.

3. Select a point somewhere near the sphere's "equator" to set the area of influence.

4. Move the mouse to the right.

(Note that in the example below, note that the object we're performing the magnet move on has been moved from global center.)

We'll use magnet operations in several of the other N-Geometry tutorials.

How the Area of Influence is Calculated

Specifying an Area of Influence Numerically

Figure 5.13 Specifying an area of influence numerically

• Influence dist lets you specify the distance used for calculating the area of influence.


• If you use either the Midpoint or Shortest methods, the distance represents the radius of the "invisible" sphere.

  
  

• If you use the Surface method, it represents the distance measured along the surface of the object.

Both of these methods are described in more detail in the N-Geometry Reference Guide.

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Congratulations!

Copyright © 1996, Nichimen Graphics Corporation. All rights reserved.