File and Edit Menus

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The File Menu

• Creating new primitives
• Opening previously saved objects
• Saving an object to disk
• Exporting an object to a different file format
• Deleting an object from N-Geometry

The GeoMenus>File menu looks like this:

Figure 2.1 The File menu

Each of the options on the File menu are described in the following sections.

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New Object

• (CLICK-L) or (CLICK-M) to select the primitive type you want to add from a menu. The New Object menu looks like this:

Figure 2.2 The Create menu

Use the New Object menu to add lights, polyhedra, and other types of primitives to your scene. Primitivies are the basic "building blocks" for creating more complex objects in N-Geometry.

Scaling Center

When you scale an object in N-Geometry or N-Dynamics, you can specify that the scaling take place with respect to this point.

To add a scaling center:

1. (CLICK-L) on GeoMenus>New Object>Scaling Center.

A list of methods for locating the center is displayed:

2. (CLICK-L) on Cursor.

You can use any of the methods listed on the menu for locating a scaling center. These methods are described in "Operations That Need an Origin," on page 1-45.

Figure 2.4 A scaling center

The scaling center appears as a single point in the N-Geometry window. You use a scaling center in scaling operations that take place around a certain point.

5. (CLICK-M) on Scale.

6. (CLICK-L) on the scaling center.

Move the mouse left and right to scale the object with respect to the scaling center.

Note. Scaling centers can be restructured under an object using the GeoMenus>Utilities>Restructure, or with the restructuring capabilities of the Browser. If you want to Scale an object around a point in an N-Dynamics script, you may want to restructure the scaling center under the object so that they share the same transformation matrix.

Rotation Axes

When you rotate an object in N-Geometry or N-Dynamics, you can specify that the rotation take place around this axis.

To add a rotation axis:

1. (CLICK-L) on GeoMenus>New Object>Rotation Axis.

A list of methods for locating the axis is displayed:

2. (CLICK-L) on Select Normal.

You can use any of the methods listed on the menu for locating a rotation axis. These methods are described in "Operations That Need an Axis," on page 1-43.

Figure 2.7 A scaling center

The rotation axis appears as a short segment in the N-Geometry window.

You use a rotation axis in scaling operations that take place around a specified axis.

5. (CLICK-M) on Rotate.

6. (CLICK-L) on Select a Segment.

7. (CLICK-L) on the rotation axis.

Move the mouse left and right to scale the object with respect to the scaling center.

Note. Rotation axes can be restructured under an object using the GeoMenus>Utilities>Restructure, or with the restructuring capabilities of the Browser. If you want to Rotate an object around an axis in an N-Dynamics script, you may want to restructure the rotation axis under the object so that they share the same transformation matrix.

Mapper

Mappers may be of three types:

• planar
• cylindrical
• spherical

Planar, cylindrical, and spherical mapper objects are represented in the N-Geometry window by icons. The lines of the mapper icon describe the location of the mapping image's edges in the projection.

Note. There are other mapper types, including parametric, per face, and frozen mappers, which are expressed in more detail in the Attributes Editor Reference Guide and the Getting Started guide.

To define how points in the image correspond to points in the mapper, pairs of numbers called UV coordinates are used. The U coordinate expresses the distance in the image from left to right, with 0 indicating the left side and 1 indicating the right side. The V coordinate describes positions from top to bottom, with 0 for the top and 1 for the bottom.

• For cylindrical and spherical projections, a line indicates where the left and right edges of the image meet in the projection. The UV coordinate origin (where U=0 and V=0) is indicated by the location of a triangular shape in the object.
• For planar and cylindrical mapper, the triangle points in the direction of increasing U values.
• For a spherical mapper, the triangle takes the form of an arc that sweeps 90° from the image seam to U=.25.

Planar Mappers

Figure 2.10 shows a planar mapper with its UV coordinates labeled, and a planar mapper bounding an octahedron.

Figure 2.10 A planar mapper bounding an octahedron

Cylindrical Mappers

Note. For hints on creating a seamless texture map, see the N-Paint Tutorial.

Figure 2.11 shows a cylindrical mapper with its UV coordinates labeled, and a cylindrical mapper bounding an octahedron.

Figure 2.11 A cylindrical mapper bounding an octahedron

Spherical Mappers

Figure 2.12 A spherical mapper bounding a cube

When they are created, mappers are separate objects; they can be restructured into an object (so that one shares or inherits its transformation matrix from another). You can also freeze the relationship of the mapper's UVs to the object, as described in the section "Make Frozen Mapper," on page 4-57.

A dynamic mapper in N-Geometry can be animated in N-Dynamics just like other objects. With a dynamic planar mapper, for example, if the object's transformation is animated differently than that of the mapper, the mapped image will slide along the surface, like the surface of an object passing through the beam of a slide projector.

You can use dynamic mappers to simulate motion without ever moving the object; for example, you could project a map of a wheel onto the wheel of a car model, then rotate the map to create the illusion that the wheel was spinning.

Creating a Mapper

1. Create the object to which you want to attach the mapper.

2. (CLICK-L) on GeoMenus>New Object>Mapper.

The following dialog box appears:

3. (CLICK-L) on the type of mapper you want to create.

4. (CLICK-L) on the Bounds Source text edit box.

An object list appears. (CLICK-L) on the object with which you want to associate the mapper.

Note that the name of the mapper changes to show the new type and object upon which the mapper is based.

Note. You can specify either an object or a face part as the bounds source for a mapper. You can display any face parts for an object if you (CLICK-R) on an object in an object list.

Restructuring the Mapper

Figure 2.14 Object transformed separately from mapper

To restructure the object and mapper into a new object:

5. Open the Browser.

6. (CLICK-L) on the Geo button.

The object and mapper are both top level objects to begin:

7. (CLICK-M) and drag the mapper node onto the object.

Figure 2.16 Restructuring a mapper and an object into a new group

As you drag the mapper, its name is outlined in red; when the text is over the target object, the box around that object turns blue. Let up on the mouse and the following dialog box appears:

8. (CLICK-L) on Yes.

This restructures the two elements into a new group, whose structure should now look like this:

9. (SHIFT-L) on the Octahedron Group, then (CLICK-L) on Axis Move>X.

Now, if you move the group, both the octahedron and the mapper move, since they are inferior objects of the group and inherit its transformation matrix.

If you want to animate both an object and a mapper together (as you do in N-Dynamics), you'll want to restructure objects like this.

Note. If you create and assign a mapper in the Browser, the superior group containing the object and the mapper is created automatically.

Note. Creating mappers is discussed in more detail in the N-Geometry Tutorial, and using the Browser for tasks like restructuring is discussed in more detail in Getting Started.

Creating Lights

• Spot lights are cone shaped; you must specify the location and the aim point for the spot light, and the radius of its perimeter at the aim point (the wide part of the cone).
• Infinite lights are located at an infinite distance from the global center and emit parallel light rays (much like a star, which is at an effectively infinite distance). You must specify a direction when creating an infinite light. The default direction is 0, 1, 0.
• Point lights radiate uniformly from a point. A light bulb suspended on a chain is a good example of a point ight. The default position is 0,0,0.
• Ambient lights are sourceless lights that are uniformly distributed in all directions. They have no fixed position. Rooms lit by indirect sunlight have "ambient" light-ambient lights cast a "tone" to an entire scene.

These lights and their characteristics are described in more detail in the Attributes Editor User Guide.

Lights are treated as objects in N-Geometry. After generating a light object, you may modify it using one of two methods:

• by selecting the light in N-Geometry and using a modify body command
• by selecting the light in the Attributes Editor and changing its parameters

Note. To select a light in N-Geometry, you must select points in the element sensitivity menu.

Initially, the view window contains a single default point light positioned at 100, 300, 150 (up and back) so that it illuminates all visible objects.

(CLICK-L) on File>New Object>light to bring up the menu that lets you specify the parameters for a new light:

Figure 2.20 Defining a new light

Each of these parameters is described in more detail below:

Table 2.1 Light parameters for lights in N-Geometry

Parameter	Light Type	Description
Name	Ambient Point Infinite Spot	Specifies the name of the light object to be created from this menu.
Type		Selects the type of light to be created from this menu, as described above.
Reference Space	Point Infinite Spot	Global positions lights using the conventional global coordinate system. If you want to render a scene as if the lights were fixed in space, select this option. Camera selects a coordinate system that is centered with and aligned to the camera's current view. Lights specified this way maintain a constant relationship to the camera, even if the camera moves. Camera space is left-handed (position z is forward). If you want to render a scene as if the lights were attached to the camera, select this option.
Brightness	Ambient Point Infinite Spot	Specifies the intensity of a light. The practical range is from 0 (least) to 1 (greatest). The actual range is unlimited in both the positive and negative directions. This flexibility can be helpful when you are illuminating dark objects; further, you can create negative lights, which subtract light from a scene. Use great care when specifying values greater than 1. In some cases, intensity values in the renderer might overflow, creating anomalous colors.
Color	Ambient Point Infinite Spot	Selects the color for the light using a palette. Figure 2.21 Selecting colors from the palette To change the values displayed on the palette, (CLICK-L) on the Edit button. For a complete description of setting light color, see the Attributes Editor User Guide.
Group	Ambient Point Infinite Spot	Specifies the initial group in which the light is placed. Light groups are arbitrary, named collections of lights which are used by N-Render as an attribute (you typically select a light group to apply to an object or group of objects). Lights can belong to any number of groups. See the N-Render documentation for a description of lights and light groups and how they affect surface characteristics.
Location	Point Spot	For a point light, specify the X, Y, and Z coordinates for the light. For a spot light, set the X, Y, and Z coordinates for the eyepoint (the sharp end of the cone).
Aim Point	Spot	Sets the X, Y, and Z location for the spot light. The location and aim point values define the length of the light and its orientation.
Radius	Spot	Sets the radius (from aim point to the edge of the light) of a spot light.
Shadowing	Spot	Specifies whether or not the light should generate shadows.
Projecting	Spot	Lets you specify that the spot light is to project an image (much like a slide through a slide projector). The image to be projected is specified with the Parameters menu. Note. You must have selected Render as your render domain (rather than GL Shade) for this option's effect to be visible.
Direction	Infinite lights	Specify the direction in which the infinite light is shining. If you (CLICK-L) on the text edit box, you can select the axis along which the light is aimed.

Creating Polyhedra

To create one of these polyhedra with other than the default values, (CLICK-R) to bring up a menu. These parameters are described in the section "Parameter Descriptions for Menu-Generated Polyhedra," on page 2-21.

Both objects shown in Figure 2.22, for example, are cylinder primitives. The object on the left is the default cylinder; the object on the right was created using the cylinder menu (it has 3 faces around (rather than 36), and it has a wedge cut). Simply modifying the polyhedron default settings is an often overlooked method for creating interesting polyhedra.

Figure 2.22 Default cylinder; cylinder created with modified settings (four sides)

Each of the basic polyhedra are described below. As with all of N-Geometry, you'll learn best by trying to create the different shapes on your own.

Tetrahedron

Figure 2.23 Tetrahedron and menu

Octahedron

Figure 2.24 Octahedron and menu

Icosahedron

Figure 2.25 Icosahedron and menu

Dodecahedron

Figure 2.26 Dodecahedron and menu

Cube

Figure 2.27 Cube and menu

Cylinder

Figure 2.28 Cylinder and menu

Sphere

Figure 2.29 Sphere and menu

Torus

Figure 2.30 Torus and menu

Parameter Descriptions for Menu-Generated Polyhedra

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