functions in contour.i -

             iso3(origin, delta, var, level, colr, var2=)  
 
     Included for compatibility of earlier versions of yorgl.  
     Please call iso3cenreg instead.  

             iso3_tree(origin, delta, var, level, colr, tree, var2=)  
 
     Extract an iso-surface from a variable on a rectangular 3D grid.  

             iso3_treecrv(xyz, var, level, colr, tree, var2=)  
 
     Extract an iso-surface from a variable on an ijk 3D grid.  
     Uses a tree created by mak_isotree.  

             iso3_treevarr(origin, delta, var, level, colr, tree, var2=)  
 
     Extract an iso-surface from a variable on a rectangular 3D grid.  
     The triangles are returned in vertex arrays.  

             iso3cencrv(xyz  
 
     Extract an iso-surface from a variable on a curvilinear 3D grid.  
     Input array var is point centered and has one extra point on  
     each side. var2, if suplied, is an auxiliary variable with  
     the same centering and size as var.  
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  
     The result is a list of triangle arrays.  

             iso3cencrvndx(xyz, var, level, colr, var2=)  
 
     Extract an iso-surface from a variable on a curvilinear 3D grid.  
     Input array var is point centered and has one extra point on  
     each side. var2, if suplied, is an auxiliary variable with  
     the same centering and size as var.  
     The result is a list of groups of triangle arrays.   
     If requested, triangle strips may extend across multiple zones.  
     Triangles are specified by indices into vectors of coordinates,   
     gradients, and auxiliary variables.   
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  

             iso3cenreg(origin, delta, var, level, colr, var2=)  
 
     Extract an iso-surface from a variable on a rectangular 3D grid.  
     Input array var is point centered and has one extra point on  
     each side. var2, if suplied, is an auxiliary variable with  
     the same centering and size as var.  
     The result is a list of groups of triangle arrays.   
     If requested, triangle strips may extend across multiple zones.  
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  
     The result is a list of triangle arrays.  

             iso3cenregndx(origin, delta, var, level, colr, var2=)  
 
     Extract an iso-surface from a variable on a rectangular 3D grid.  
     Input array var is point centered and has one extra point on  
     each side. var2, if suplied, is an auxiliary variable with  
     the same centering and size as var.  
     The result is a list of groups of triangle arrays.   
     If requested, triangle strips may extend across multiple zones.  
     Triangles are specified by indices into vectors of coordinates,   
     gradients, and auxiliary variables.   
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  

             iso3cenregngrd(origin, delta, var, level, colr, var2=)  
 
     Extract an iso-surface from a variable on a rectangular 3D grid.  
     Input array var is point centered and NO guard points.   
     var2, if suplied, is an auxiliary variable with  
     the same centering and size as var.  
     The result is a list of groups of triangle arrays.   
     If requested, triangle strips may extend across multiple zones.  
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  
     The result is a list of triangle arrays.  

             iso3hex(xyz, grad, hexndx, var, level, colr, var2=)  
 
     Extract an iso-surface from a variable on an arbitrarily  
     connected 3D grid of hexahedra.  
     xyz, grad, and var are coordinates, gradients, and  
     variable values at the points of the grid.  
     var2, if suplied, is an auxiliary variable with  
     the same centering and size as var.  
     hexndx has 8 indices into the xyz etc. arrays for   
     each zone.  
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  
     The result is a list of triangle arrays.  

             iso3ndx(origin, delta, var, level, colr, var2=)  
 
     Included for compatibility with earlier versions of yorgl.  
     Please call iso3cenregndx instead.   
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  

             iso3zcencrv(xyz, var, level, colr, var2=)  
 
     Extract an iso-surface from a variable on a curvilinear 3D grid.  
     Input array var is zone centered and has one extra zone on  
     each side. var2, if suplied, is an auxiliary variable with  
     the same centering and size as var.  
     The result is a list of groups of triangle arrays.   
     If requested, triangle strips may extend across multiple zones.  
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  
     The result is a list of triangle arrays.  

             iso3zcencrvndx(xyz, var, level, colr, var2=)  
 
     Extract an iso-surface from a variable on a curvilinear 3D grid.  
     Input array var is zone centered and has one extra zone on  
     each side. var2, if suplied, is an auxiliary variable with  
     the same centering and size as var.  
     The result is a list of groups of triangle arrays.   
     If requested, triangle strips may extend across multiple zones.  
     Triangles are specified by indices into vectors of coordinates,   
     gradients, and auxiliary variables.   
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  

             iso3zcenreg(origin, delta, var, level, colr, var2=)  
 
     Extract an iso-surface from a variable on a rectangular 3D grid.  
     Input array var is zone centered and has one extra zone on  
     each side. var2, if suplied, is an auxiliary variable with  
     the same centering and size as var.  
     The result is a list of groups of triangle arrays.   
     If requested, triangle strips may extend across multiple zones.  
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  
     The result is a list of triangle arrays.  

             iso3zcenregndx(origin, delta, var, level, colr, var2=)  
 
     Extract an iso-surface from a variable on a rectangular 3D grid.  
     Input array var is zone centered and has one extra zone on  
     each side. var2, if suplied, is an auxiliary variable with  
     the same centering and size as var.  
     The result is a list of groups of triangle arrays.   
     If requested, triangle strips may extend across multiple zones.  
     Triangles are specified by indices into vectors of coordinates,   
     gradients, and auxiliary variables.   
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  

             iso3zcenreg(origin, delta, var, level, colr, var2=)  
 
     Extract an iso-surface from a variable on a rectangular 3D grid.  
     Input array var is zone centered and has one extra zone on  
     each side. var2, if suplied, is an auxiliary variable with  
     the same centering and size as var.  
     The result is a list of groups of triangle arrays.   
     If requested, triangle strips may extend across multiple zones.  
     Uses a 6 tetrahedron decomposition of each hexahedral zone.  
     The result is a list of triangle arrays.  

             mak_isotree(var)  
 
     Build an octree for use in making iso-surfaces.  

             mak_slice_treecrv(xyz,guard=)  
 
     Extract a slicing plane on an ijk 3D grid.  

             slice_tree(sizes, origin, delta, point, pl_normal, var2, guard=)  
 
     Extract a slicing plane on a rectangular 3D grid.  
     If var2 is not null, return it's value at each vertex of the  
     slice plane.  
     sizes= [nx,ny,nz] is the grid size.  

             slice_treecrv(xyz, point, pl_normal, tree, var2=)  
 
     Extract a slicing plane on an ijk 3D grid using a pre-computed tree.  
     var2 is an optional point-centered variable. If present,   
     it will be interpolated to the points on  
     the slicing plane. The resulting variable can be   
     turned into a color and the slice plane can then be smoothly  
     colored using one color per vertex instead of one  
     color per triangle.