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Mastering
3D Studio MAX R3 |
Space Warps
After the master object, modifiers, and transforms have been evaluated,
MAX evaluates all of the space warps that have been applied to
the object. Like modifiers, space warps deform object geometry. The difference
is that the effect of a space warp upon an object changes as the object
is transformed in space. Space warp bindingsthe short tags that
indicate that a space warp had been applied to an objectappear at
the top of the modifier stack, above the master object and its modifiers
and transforms (see Figure 2.11).
FIGURE
2.11 Space warp bindings are separated from
an objects modifiers by a double line.
Object Properties
MAX evaluates object properties last. Object properties include the name,
color, material assignment, display properties, linking information, G-buffer
ID number, and attributes of rendering such as shadow casting and receiving.
These properties can be viewed by right-clicking a selected object and
opening the Object Properties dialog box (displayed in Figure 2.12).
Of all the object properties, materials provide the biggest opportunity
for variation. Some materials cover the surface of an object like wallpaper;
others go through to the core. They give objects characteristics like
color, pattern, texture, shininess, and transparency. These effects can
be layered or combined with maps to simulate the complexity of real-world
surfaces (as shown in Figure 2.13).
You add maps to materials by linking the program to external image files
or by generating maps from internal procedures. Both image maps and procedural
maps may be animated. After you have incorporated a map into a material
(like the box in Figure 2.14), you can manipulate its color attributes
and its surface projection coordinates.
FIGURE
2.12 The Object Properties dialog box allows
you to change existing properties and define your own.
FIGURE
2.13 The material on this teapot uses a Cellular
procedural map for its Diffuse map as well as its Opacity map.
FIGURE
2.14 Mirroring and tiling commands cause a map
to repeat across the surface of the box. (The original map was Cloud2.jpg,
which ships with MAX.)
Unlike image maps, which are limited to a two-dimensional array of pixels
even when wrapped around a 3D object, procedural maps can be three-dimensional:
the map itself has depth. This means that when you cut away a part of
an object with Boolean subtraction, the map pattern continues on the inside
surfaces. Procedural maps (like the one in Figure 2.15) are generated
by the program in a mathematical procedure.
FIGURE
2.15 A 3D procedural map is revealed inside
the cutaway surface of the sphere. Notice its continuity with the outside
surface.
Materials can incorporate an unlimited number of maps. To keep track
of them, MAX places the maps in a branching hierarchy called a material
tree. This hierarchy can be viewed with the Material/Map Navigator and
the Material/Map Browser (see Figure 2.16).
FIGURE
2.16 A complex material and its hierarchy displayed
in the Material/Map Navigator
Understanding MAXs
Concepts of Space
In Chapter 1, you learned how 3D space begins at a defined origin and
extends infinitely into space, using the X, Y, and Z axes to measure distance.
Now, lets look at how different systems of reference can be used
to measure space from different perspectives.
A system of reference is a navigational tool that indicates your
position and orientation. You select different systems of reference from
the Reference Coordinate System drop-down list (on the Main Toolbar) depending
on where you are and what you are doing.The most important systems of
reference are the world coordinate system and the local coordinate
system. World coordinates define the space of the entire scene, or
world space; local coordinates define the space around an object, or object
space. The other coordinate systems are variations on world or local systems
of reference that are used for performing object transforms under specific
circumstances.
World Coordinates
The world coordinate system measures space in absolute terms using a
fixed system of reference. You can think of it as an intergalactic system
of navigation, with the origin of the universe at its core. The program
uses this system to keep track of all of the objects in your scene. Use
this system to locate objects in relation to the entire scene.
Whenever you select an object, MAX displays X, Y, and Z axes that reflect
the current coordinate system. World coordinates are fixed in space; the
axes shown match those of the home grid, as in Figure 2.17, no matter
which way the object is pointed.
FIGURE
2.17 Using world coordinates, the axes of the
objects home grid always align to the axes of the world coordinate
system.
Local Coordinates
The local coordinate system is an object-based system that uses the pivot
of an object as its origin (as illustrated in Figure 2.18). If world coordinates
measure the universe, then local coordinates measure planetary space.
The position and orientation of an objects local coordinate system
is measured and indicated by the objects pivot. This is the system
that the program uses when it modifies the geometry of an object, or performs
a transform in local coordinates.
FIGURE
2.18 The axes of the local coordinate system
indicate the position and orientation of an object.
Screen Coordinates
Screen coordinates align the axes to the view plane of the monitor screen.
X and Y align horizontally and vertically to the screen, with Z directed
in and out of the screen (as in Figure 2.19). This orientation persists
no matter how you rotate your view of the scene. Use screen coordinates
whenever you want to transform an object in relation to the edges of an
active viewport.
FIGURE
2.19 Screen coordinates always face
the viewer.
View Coordinates
View coordinates align to the visible plane of the home grid (see a top
view example in Figure 2.20). In a variation on world coordinates, in
view coordinates, the Z axis always points away from the grid. View coordinates
are thus not a fixed system of reference, because different grid planes
face different ways in different views.
FIGURE
2.20 In view coordinates, the Z axis always
points away from the grid.
Grid Coordinates
Grid coordinates align to the visible plane of the active grid (see Figure
2.21). At first glance, grid coordinates seem identical to view coordinates,
in that the Z axis is placed perpendicular to the visible grid. The difference
is that grid coordinates align not just to the home grid, but to any grid
that is active, including user grids. Use this system when you want to
transform objects with respect to the planes and axes defined by a grid
object.
FIGURE
2.21 Grid coordinates align to the visible plane
of the active grid.
Parent Coordinates
Parent coordinates align to the local coordinates of an objects
parent (see Figure 2.22). When the parent coordinate system is chosen,
child objects transform with respect to the local coordinate system of
their parent objects. This is different than linking, in which the child
inherits the transforms of a parent using whatever transform coordinate
system is selected. If an object is not linked to a parent, it is considered
a child of the world, and uses the world coordinate system by default.
This system is useful when developing inverse kinematics.
Pick Coordinates
Pick coordinates align to the local coordinates of any object that you
choose (see Figure 2.23). Like the parent coordinate system, pick coordinates
use the local coordinates of another object as the locus of transforms.
The difference is that pick coordinates allow you to select any other
object in the scene as the locus of transformation. Use this system when
you want to transform one object in relation to another without linking
them in other ways.
FIGURE
2.22 Parent coordinates align to the local coordinates
of an objects parent.
FIGURE
2.23 Pick coordinates align to the local coordinates
of any object you choose.
Understanding MAXs
Concepts of Time
In animation, time is a series of discrete moments strung together by
the eye and mind. When you view a rapid succession of images, each one
persists in your memory long enough to superimpose it on the one that
follows. When the images depict a logical progression across a sequence
of frames, your mind interprets the images as animation.
© 2000, Frol (selection,
edition, publication)
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