Re: Assigning color to a user defined grid

• To: VSOP User <vsop@xxxxxxxxxxxx>
• Subject: Re: Assigning color to a user defined grid
• From: "From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>" <billh@xxxxxxxxxxxxx>
• Date: Sun, 25 Feb 2001 12:03:25 -0600 (CST)

> . . .
> I have been able to draw the grid using the Gridded2DSet and the
> UnionSet constructs, similiar to the Rivers example (in
> visad/examples/Rivers.java). Each set of corners is used to form a 
> Gridded2DSet, and the UnionSet is used to form a disjoint set of
> these.
> 
> How do I now create a function from a Gridded2DSet, to a node and then
> from a node to a node value, then to RGB ? 

All current implementations of visad.Function assign values
to vertices rather than regions, so it is a little complex.

Rather than constructing a UnionSet of your Gridded2DSets,
construct each Gridded2DSet as the boundary of one node,
construct a FlatField with that Gridded2DSet as its domain
Set and range values that you can map to red, green and blue.

Then construct a FieldImpl whose range values are all the
FlatFields, and whose domain is a simple index. The MathType
of the FieldImpl would be something like:

  (index -> ((x, y) -> (r, g, b)))

and each FlatField would have MathType ((x, y) -> (r, g, b)).
Let the range r, g, b values be constant for each FlatField,
to give constant color to each node.

Good luck,
Bill