Page 312 - Kitab3DsMax

Part III: Modeling Basics

The pop-up menu includes options to convert to editable mesh, editable poly, editable patch, and NURBS.
If a shape or spline object is selected, then the object can also be converted to an editable spline. Using any
of the Convert To menu options collapses the Modifier Stack.

Note
Objects can be converted between the different types several times, but each conversion may subdivide the
object. Therefore, multiple conversions are not recommended. n
Converting between object types is done automatically using Max’s best guess, but if you apply one of the
Conversion modifiers to an object, several parameters are displayed that let you define how the object is
converted. For example, the Turn to Mesh modifier includes an option to Use Invisible Edges, which
divides polygons using invisible edges. If this option is disabled, then the entire object is triangulated. The
Turn to Patch modifier includes an option to make quads into quad patches. If this option is disabled, all
quads are triangulated.
The Turn to Poly modifier includes options to Keep Polygons Convex, Limit Polygon Size, Require Planar
Polygons, and Remove Mid-Edge Vertices. The Keep Polygons Convex option divides any polygon that is
concave, if enabled. The Limit Polygon Size option lets you specify the maximum allowable polygon size.
This can be used to eliminate any pentagons and hexagons from the mesh. The Require Planar Polygons
option keeps adjacent polygons as triangles if the angle between them is greater than the specified
Threshold value. The Remove Mid-Edge Vertices option removes any vertices caused by intersections with
invisible edges.
All Conversion modifiers also include options to preserve the current subobject selection (including any
soft selection) and to specify the Selection Level. The From Pipeline option uses the current subobject selec-
tion that is selected on the given object. After a Conversion modifier is applied to an object, you must col-
lapse the Modifier Stack in order to complete the conversion.

Understanding Normals

Before moving on to the various subobjects, you need to understand what a normal is and how it is used to
tell which way the surface is facing. Normals are vectors that extend outward perpendicular to the surface of
an object. These vectors aren’t rendered and are used only to tell which way the surface face is pointing. If
the normal vector points toward the camera, then the polygon is visible, but if it points away from the cam-
era, then you are looking at its backside, which is visible only if the Backface Cull option in the Object
Properties dialog box is disabled.
Several other properties also use the normal vector to determine how the polygon face is shaded, smoothed,
and lighted. Normals are also used in dynamic simulations to determine collisions between objects.

Viewing normals
In all mesh subobject modes except for Edge, you can select the Show Normals option to see any object’s
normals and set a Scale value. Figure 10.1 shows a Plane, a Box, and a Sphere object. Each object has been
converted to an Editable Mesh with all faces selected in Face subobject mode and with the Show Normals
option selected.

264

6/30/10 4:19 PM
17_617779-ch10.indd 264 6/30/10 4:19 PM
17_617779-ch10.indd 264