The PointSet node specifies a set of 3D points in the local coordinate
system and associated colors.
This node contains two fields: color and coord.
The color field defines a Color
node. The coord field specifies a Coordinate
node.
The color is optional, the default values being applied if the field
is not specified. If a Material
node is specified the default color is the emissive color from this node.
Note that both the default emissive color and background are black, so
if no color is specified and the default background is used you won't be
able to see the points.
There must be as many components in the color field as in the coord
field.