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VERTEX MAPS

 Vertex maps are modo’s way of tying extra numbers into certain vertices in

 your model. Extremely flexible and powerful, they are used in modo for vertex 

selection sets, weight maps, subdivision sharpness maps, texture coordinates

( UVs ), vertex coloring, and blend shapes ( morph maps ). A vertex map is distin-

 guished by its name, size, and type. The size of a vertex map tells how many numbers it associates with each vertex, so a weight-type vertex map with a sin-

 gle weight per vertex has a size of 1, while a color-type vertex map will have a 

size of 3, for the red, green, and blue values stored with the vertices. A vertex 

map could even have a size of 0, with no numbers attached!

 There can be many vertices in a model that have NO numbers associated with

them in a given vertex map. Indeed it makes sense to only attach these extra 

 values where they are needed. If a vertex does not have an entry in a particular vertex map, tools will tend to interpret it as a value of 0.0, but there is a diff er-

ence. For example with selection sets, the vertex map has a size of 0, so the set

is just those vertices with an entry in the vertex map.

Vertex maps values are interpreted in modo in diff erent ways depending on

their type ( UVs, weights, morphs, etc. ). In many cases each of these vertex map

types has a distinct set of tools, and it is not critical to understand that they 

are all diff erent facets of the same underlying thing. One can easily buildmorph targets and edit UVs without knowing that they are both stored in ver-

tex maps. The Vertex Map Math tool is an exception, as it encourages you to

combine elements from vertex maps, making a weight map from the magni-

tude of a morph displacement, or scaling a vertex color by the texture U coor-

dinate value. New vertex map types may be added by scripts or plug -ins, but

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here is a list the most common vertex map types ( and sizes ) you may run

across:

 Type Size Description

pick 0 Vertex selection set

edgepick 0 Edge selection set

 weight 1 Weight map

subvweight 1 Subdivision weight map

texture 2 UV map

position 3 Vertex position

morph 3 Vertex relative morph off set

spot 3 Vertex absolute morph position

normal 3 Vertex normal vector

rgb 3 Vertex color

rgba 4 Vertex color with alpha  

In some cases, a vertex must have a diff erent vertex map value depending 

 which of the polygons that share it is being considered. A common example

 would be the seam in texture coordinates around a cylinder. At the seam, a ver-

tex is expected to have a value of 0.0 for the polygon with the left edge of the

image, and a value of 1.0 for the polygon that got mapped with the far right

edge of the image. This 2- valued seam vertex breaks the continuous texture

coordinate values, and requires a “Discontinuous Vertex Map”.

 A Discontinuous Vertex Map is really just the discontinuous part of a regular

 vertex map. In it vertices are identified by which polygon they are associated

 with, not just by the vertex itself. Thus a vertex may have one regular vertex map value in a given map, and several other values in that same map which are

tied to one of the polygons sharing that vertex.

Discontinuous vertex map values are most important in texturing. In the UV

 Texture Viewport, vertices with discontinuous values ( discos ) may appear more

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than once, first in their continuous value UV position, then as part of the poly -

 gon that gives them their discontinuous value. Discontinuous vertex maps are

also used for edge-based creasing of subdivision surfaces.

For examples of Vertex Map usage, refer to the video clip tutorials in Documenta -tion\pages\ video\VertexMaps

Vertex Maps