NAME
     Grid 2 TxtMesh - create quad mesh from 2d field; support for 
	texture mapping, using inline-texture calls

Author: Scott Goodyear

     Type	   mapper

     Inputs	   2D field scalar float, uniform | rectilinear | irregular
                            (REQUIRED)
		   2D image (scalar 4-vector byte)
			    (OPTIONAL)
                   Colormap

     Outputs	   Geometry - quad mesh

     Parameters	   
     Name               Type        Default       Min       Max
     Z scale            float
     Normalize          toggle
     GenNormals         toggle
     GenWireframe       toggle
     UV orientation  0011:1100:0101:1010:0110:1001
     StartX             float
     StartY             float
     GridStepSize       float
     Downsize           int




DESCRIPTION

	The texture mesh module serves two needs.  First, the need for
 	a robust module for mapping 2D data to quadrilateral meshes
	is served.  The input 2D data may be a 2D uniform field, in
	which case the x,y coordinates for the output mesh is derived
	from the extents information (if present) or using a mapping
	from indeces to space if no extents information is present.  The
	z values are obtained from the data in the field.

	In 2D rectilinear fields, the x,y coordinates are explicitly
	provided.  The z values are obtained from the data.

	In 2D, 3-space irregular fields, all coordinates are specified.
	In 2D, 2-space irregular fields, the mapping is the same as
	in rectilinear data.

	The second need fulfilled by this module is support for texture
	mapping.  Two types are supported.  The first, called "dynamic"
	in AVS parlance, is the traditional type of texture mapping where
	the coloring of the surface is postponed until rendering time.
	The second type, called "explicit" here will color the vertices
	of the field based upon the image on the second input port, along
	with the uv coordinate ranges specified by the user.

	Control over the uv coordinates is explicitly supported for this
	module so that the user may move the texture around, or scale the
	texture using the parameters provided.  Non-affine transformations
	along with rotations (of textures on the surface) are not
	supported.

        This module uses in-line field texture calls available from
	AVS 5.01.

        Note: This module at present does not work on Dec Alpha OSF.