8

VertexPaint Modifier 919
The amount of color that 3ds Max applies to a
vertex depends on the distance of the vertex from
the position of the paint cursor on t he face. The
more you select a face, the more it changes to the
new color. The Opacity button also controls the
strength of the color. 3ds Max shades the color, so
if you have one green vertex and two w hite vertices
for one face, for example, you’ll see a gradient on
that face.
VertexPaint mod ifier also lets you paint values for
the vertex alpha and illumination channels. These
channels affect the transparency and shading of
vertex colors, respectively.
Tip: If you select faces using the selection tools
of the VertexPaint modi fier, you restrict your
painting to only the selected faces, as opposed to
allfaces. Thisallowsyoutosharplydefinethe
edges of you r painted selection.
Tip: You can streamline the painting process
by using the
Brush Presets tools (page 3–737) .
About Map Channels and Vertex Color,
Vertex Alpha, and V er tex Illum
When using vertex paint, it is helpful to
understand how 3ds Max manages vertex color,
alpha, illumination, and map channels. All of
these different pieces of information are actua lly
stored and managed in 3ds Max using the same
underlying system.
The map channels are defined as triple-value
channels (tuples) with a unique integer ID number
ranging from - 2 to 99. The first five map channels
have specific and familiar usages:
• Channel (2): UVW “ second pass” texture
mapping coordinates
• Channel (1): UVW standard texture mapping
coordinates
• Channel (0): RGB vertex color
• Channel (-1): FLOAT vertex alpha (really only
1 value needed)
• Channel (-2): RGB vertex illumination
Every geometric vertex of a mesh or poly object
can be assigned up to 102 channel values (99 + 3).
The negative numbering scheme for vertex alpha,
and illumination is act ually historic: it was done
to preserve the meaning of existing map-channel
data in older 3ds Max files b efore vertex alpha and
illumination were added.
You can paint on any arbitrary channel, and to use
one or more channels for any arbitrary meaning
for a given vertex. It is useful in development
of content for games to paint on arbitrary map
channels numbered hig her than those used for
texture mapping (such as channels 3, 4, 5). These
can b e used to store logical infor mation about a
vertex, whether it is “slippery” or “explosive”, for
example.
A single vertex can be assigned a stack of map
channels that carry different meanings. When the
modifier stack is collapsed, these map channels
are preserved.
The new VertexPaint mo difier takes this into
consideration through its simple exposure of map
channel IDs for display and painting.
About Painting in Layers
The layer system allows you to paint changes on a
single lay er, then make another layer on top of that,
and paint additional changes. This can be used to
store different versions or variations of your vertex
color painting.
Every layer has a blending mode that it uses to
determine how it combines with the other layers.
You can assign vertex colors using the
Assign
Vertex Colors utility (page 2–1544)
,thenadd
another layer, change the layer m ode operator to
Lighten, and paint with a white paintbrush, to
lighten up areas. There are 15 different modes to
use, and many tasks that can be accomplished
using paint layers.