9

VertexPaint Modifier 937
• Channel (2): UVW “second pass” texture
mapping coordinates
• Channel (1): UV W standard texture mapping
coordinates
• Channel (0): RGB vertex color
• Channel (-1): FLOAT vertex alpha (really only
1 va lue needed)
• Channel (-2): RGB vertex illumination
Every geometric vertex of a mesh or poly object
can be assigned up to 102 channel va lues (99 + 3).
The negative numbering scheme for vertex alpha,
and il lumination is actually historic: it was done
to preserve the meaning of existing map-channel
data in older scene files before 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 higher than those used for
texture mapping (such as channels 3, 4, 5). These
can be used to store logical information about a
vertex, whether it is “slippery” or “explosive”, for
example.
A sing le vertex can be assig ned a stack of map
channels that carry different meanings. When the
modifier st ack is collapsed, these map channels
are preserved.
The new VertexPaint modifier 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 p aint changes on a
single layer, 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 mo de that it uses to
determine how it combines with the other layers.
You can assign vertex colors using the Assign
Vertex Colors utility (page 2–1734),thenadd
another layer, change t he layer mode operator
to Lighten, and paint with a white paintbrush
to lighten up areas. Fifteen different modes are
available, and many tasks can be accomplished
using p aint layers.
OneoftheprimaryadvantagesofVertexPaint
is its use of the modifier stack as a kind of
image-composite stack. Each VertexPaint modifier
ser ves as a single layer in the composite. You can
move layers up and down the stack, enable and
disablethem,andflattenthestackusingCondense
to single layer.
B ack ward Compatibility
If you load an older file that uses a previous version
of the VertexPaint modifier, then the legacy
modifier will b e loaded when the file is opened.
The legacy mo difier has not b een changed, and
the two modifiers are not inherently compatible
in terms of their data format during loading and
savi ng.
If you have vertex color data in a legac y VertexPaint
modifier, you can use the Condense to single layer
tool of the new modifier to migrate the vertex
colors into the new modifier.
Procedures
To add scene lighting into a n object’ s ver tex color:
1.
Select the objects in the scene that you want to
color.
2. OntheModifypanel,chooseVertexPaintfrom
the modifier list.
The floating Paintbox (page 1–941) appears,
docked to the left edge of the view por ts.
3. Open the Assign Vertex Colors rollout.