mesh_arr - Geometric procedure

Creates a mesh.


Description

Creates a mesh. Geometry (vertex coordinates) and topology (edges and faces) are defined by data in arrays. Edges can belong to only one face or join two different faces.An edge that joins 2 faces is implemented as a pair of halfedges with opposite direction, each belonging to one of the two faces. An edge belonging only to one face is also implemented as a pair of halfedges. In this case the extra halfedge has no parent face. All edges must be represented by two halfedges. Current implementation of faces assume all faces are triangular.

A mesh can be defined without faces. If faces are missing, the mesh becomes a wireframe mesh without any surface. A mesh can even be defined without edges. If edges are missing the mesh is reduced to a point cloud.

An optional array of floats with arbitary length can be saved together with the mesh. If for example nxfloats = nvertices, a float value can be saved for each vertex.

Syntax

mesh_arr(id, nvertices,p,eh,nhalfedges,ev,oh,nh,pf,nfaces,h,nxfloats,xf:attributes);

REF	id;
INT	nvertices;
VECTOR	p(nvertices);
INT	eh(nvertices);
INT	nhalfedges;
INT	ev(nhalfedges);
INT	oh(nhalfedges);
INT	nh(nhalfedges);
INT	pf(nhalfedges);
INT	nfaces;
INT	h(nfaces);
INT	nxfloats
FLOAT	xf(nxfloats)

Principal parameters

id	- Local identity
nvertices	- Number of vertices
p	- Array of vertex coordinates
eh	- Array of indexes to emanating halfedges (the halfedge that starts in this vertex)
nhalfedges	- Number of  halfedges (may be zero if nfaces is zero)
ev	- Array of indexes to end vertices (the vertex that ends this halfedge)
oh	- Array of indexes to opposite halfedges (the other halfedge of this edge)
nh	- Array of indexes to next halfedges (the next halfedge around the face)
pf	- Array of indexes to parent faces (the face bounded by this halfedge)
nfaces	- Number of faces (may be zero)
h	- Array of indexes to halfedges (any one of the the halfedges belonging to this face)

Optional parameters

nxfloats	- Number of extra float values
xf	- Array of extra float values

Attributes

PEN	- Pen or colour number
LEVEL	- Level number
BLANK	- Visible(0=default) or invisible(1)
WIDTH	- Linewidth
MFONT	- Mesh font.  Auto(0=default),  Box(1),  Pointcloud(2),  Edges(3),  Faces(4)