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NOTE:
A typical
PC game texture budget is calculated by examining
the video memory of the target machine, currently
about 2 MB. That video memory must store the screen
area, (about 302 KB), an offscreen draw buffer of
the same size, and finally the texture memory. That
limits texture memory for the entire scene to about
1.4 MB, or the size of a floppy disk. The textures
are mapped into the screen area by choosing which
pixels of the texture to copy into which area of
the screen memory, an operation usually performed
by the video card itself.
Because
texture space is at a premium and takes longer to
draw to the screen anyway, clever use of material
color is a must. One technique is the use of vertex
shading. Each vertex of a polygon may, in fact,
have a different color, and when they are drawn
to the screen, the shading engine creates a gradient
between the vertices with different coloration.
This method is growing in popularity and is completely
supported by Softimage. Softimage can even convert
a texture map on a polygonal mesh into vertex colors.
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Figure
7.4 Two low poly vehicles, with 256*256 pixel
texture maps from the Microsoft Combat Flight Simulation game,
modeled and textured by David Choi. Copyright 1998 Microsoft
Corp.
Figure 7.5
A very small texture sheet used to texture Microsoft
low poly models for the Microsoft Combat Flight Simulation
game. Texture map painted by David Choi. Copyright 1998 Microsoft
Corp.
Make Mine
Pink: Selecting Polygons
The Polygon Selection
methods are listed in the Polygon menu cells (see Figure 7.6).
Those polygons selected on a given object are highlighted
in a translucent pink shade in the Wireframe views (see Figure
7.7). When you switch to the POL mode, only the selected,
pink polygons are transformed by the Scale, Rotate, and Translate
menu cells. Many other commands are likewise restricted to
the selected group of polygons.
Figure
7.6 The Polygon menu cells in the Model module.
You can select
polygons by tagging the vertices of the polygon desired and
executing the Polygon->Tag Vertex command. I do not find
this command useful, however. A more popular method is the
Polygon->Select by Rectangle command (supra key Y), which
you use by dragging a Marquee around a polygon or group of
polygons. When you drag with the left mouse button, those
polygons entirely within the Marquee are selected and shown
in pink in the Wireframe view windows. If you use the middle
mouse button, those within the Marquee are deselected, and
if you use the right mouse button, they are toggled to the
opposite of their previous state.
Figure
7.7 A model with selected polygons highlighted
in pink.
The Select by
Rectangle method selects polygons on either side of an object,
so be sure to check that only those desired are highlighted
before you transform the selected group.
The newest method,
appearing in version 3.5, is Polygon->Select by Raycasting
(supra key G). When Select by Raycasting is active, hold down
the left mouse button to select the polygon directly under
your pointer. Only polygons with normals pointing towards
you are selected, so polygons on the backside of an object
are not added to the selected group of polygons. If no polygons
become selected when you use the G supra key, the normals
may be inverted. When you raycast with the middle mouse button,
you deselect polygons, while the right mouse button toggles
polygons.
