section g of routines in pl3d.i

Home Manual Packages Global Index Keywords Quick Reference | # functions in pl3d.i - g
get3_centroid |
                 get3_centroid(xyz, nxyz)
              or get3_centroid(xyz)

         return 3D centroids for polygons with vertices XYZ.  If NXYZ is
         specified, XYZ should be 3-by-sum(nxyz), with NXYZ being the
         list of numbers of vertices for each polygon (as for the plfp
         function).  If NXYZ is not specified, XYZ should be a quadrilateral
         mesh, 3-by-ni-by-nj (as for the plf function).  In the first case,
         the return value is 3-by-numberof(NXYZ); in the second case, the
         return value is 3-by-(ni-1)-by-(nj-1).
         The centroids are constructed as the mean value of all vertices
         of each polygon.

    interpreted function, defined at i/pl3d.i   line 480
SEE ALSO: | get3_normal, get3_light
get3_light |
                 get3_light(xyz, nxyz)
              or get3_light(xyz)

         return 3D lighting for polygons with vertices XYZ.  If NXYZ is
         specified, XYZ should be 3-by-sum(nxyz), with NXYZ being the
         list of numbers of vertices for each polygon (as for the plfp
         function).  If NXYZ is not specified, XYZ should be a quadrilateral
         mesh, 3-by-ni-by-nj (as for the plf function).  In the first case,
         the return value is numberof(NXYZ); in the second case, the
         return value is (ni-1)-by-(nj-1).
         The parameters of the lighting calculation are set by the
         light3 function.

    interpreted function, defined at i/pl3d.i   line 363
SEE ALSO: | light3, set3_object, get3_normal, get3_centroid
get3_normal |
                 get3_normal(xyz, nxyz)
              or get3_normal(xyz)

         return 3D normals for polygons with vertices XYZ.  If NXYZ is
         specified, XYZ should be 3-by-sum(nxyz), with NXYZ being the
         list of numbers of vertices for each polygon (as for the plfp
         function).  If NXYZ is not specified, XYZ should be a quadrilateral
         mesh, 3-by-ni-by-nj (as for the plf function).  In the first case,
         the return value is 3-by-numberof(NXYZ); in the second case, the
         return value is 3-by-(ni-1)-by-(nj-1).
         The normals are constructed from the cross product of the lines
         joining the midpoints of two edges which as nearly quarter the
         polygon as possible (the medians for a quadrilateral).  No check
         is made that these not be parallel; the returned "normal" is
         [0,0,0] in that case.  Also, if the polygon vertices are not
         coplanar, the "normal" has no precisely definable meaning.

    interpreted function, defined at i/pl3d.i   line 421
SEE ALSO: | get3_centroid, get3_light
get3_xy |
                 get3_xy, xyz, x, y
              or get3_xy, xyz, x, y, z, 1

         Given 3-by-anything coordinates XYZ, return X and Y in viewer's
         coordinate system (set by rot3, mov3, orient3, etc.).  If the
         fifth argument is present and non-zero, also return Z (for use
         in sort3d or get3_light, for example).  If the camera position
         has been set to a finite distance with setz3, the returned
         coordinates will be tangents of angles for a perspective
         drawing (and Z will be scaled by 1/zc).

    interpreted function, defined at i/pl3d.i   line 520
SEE ALSO: | sort3d, get3_light, rot3, setz3, set3_object
gnomon |
                 gnomon
              or gnomon, onoff

         Toggle the gnomon display.  If ONOFF is non-nil and non-zero,
         turn on the gnomon.  If ONOFF is zero, turn off the gnomon.
         The gnomon shows the X, Y, and Z axis directions in the
         object coordinate system.  The directions are labeled.
         The gnomon is always infinitely far behind the object
         (away from the camera).
         There is a mirror-through-the-screen-plane ambiguity in the
         display which is resolved in two ways: (1) The (X,Y,Z)
         coordinate system is right-handed, and (2) If the tip of an
         axis projects into the screen, it's label is drawn in opposite
         polarity to the other text on the screen.

    interpreted function, defined at i/pl3d.i   line 734