Phil McDonald, NOAA/ERL/Forecast Systems Laboratory
AVS Modules						            surface mesh
NOAA/ERL/Forecast Systems Laboratory


NAME

	surface web - create a 3D wire web object from a surface object

SUMMARY

	Name		surface web

	Type		mapper

	Inputs		geometry

	Outputs		geometry

	Parameters

	    Name		Type		Default		Min Max Choices

	    web density		integer		0		0, unbounded

DESCRIPTION

	The surface web module creates a 3D wire web from a surface object
	created from a 3D field.  Modules that create surfaces, like the
	isosurface and field to mesh modules, represent the surfaces with
	polytriangle strips.  The web is created by running "strings", or lines,
	from each vertex of each polygon defined by these strips to the line
	segment opposite the vertex.  The web density is the number of strings
	run from each vertex.  The edges of the polygons are always shown, even
	if the web density is zero.

INPUTS

	Input Geometry

	    The input for surface web must be a geometry object defined by
	    polytriangle strips.  Any other type of object is ignored.

PARAMETERS

	web density

	    The web density parameter controls the number of web strings that
	    radiate from each vertex of the surface.  The line segement 
	    opposite each vertex is divided into density + 1 equal sub-segments.
	    Consequently, the angular spacing between the strings will vary.
	    The edges of the polygons defined by the polytriangle strips will
	    always be drawn, even when the web density is zero.

OUTPUTS

	Output Geometry

	    All of the lines created by surface web are placed in an object
	    named "surface web".  This includes not only any web lines, but
	    the polygon edges as well.

EXAMPLES

	This example creates a wire web from an isosurface of a field.

		           READ FIELD
		                |
		           ISOSURFACE
		                |
		           SURFACE WEB
		                |
                         RENDER GEOMETRY
                                |
                          DISPLAY PIXMAP

LIMITATIONS

	Since each web string is created as a disjoint line, very dense webs of
	surfaces with many, many polytriangles will be very cumbersome.

AUTHOR

	Phil McDonald, NOAA/ERL/Forecast Systems Laboratory


NOAA/ERL/Forecast Systems Laboratory
AVS Modules						             surface web