&FIELD: AREA


geometry

  Sets a limiting rectangle or a limiting box. If only 4
  numbers are given, then these are interpreted as the
  range in (x,y) or in (r,phi) and the range in z is left
  unchanged.

  Field plots are made only over the part of the viewing
  plane that is located inside the box.

  Particles are allowed to drift inside the limits of the
  box.

  [The initial default is taken from the cell dimensions.]

X-Y

  Requests an x-y view, at z=0.

  In this kind of view, any solids that may have been entered
  will not be shown.

  [This is the initial default for Cartesian cells and cells
  that have a tube, provided no VIEW is specified.]

X-Z

  Requests x-z views, at y=0.

  In this kind of view, any solids that may have been entered
  will not be shown.

  [X-Y is default]

Y-Z

  Requests y-z views.

  In this kind of view, any solids that may have been entered
  will not be shown.

  [X-Y is default]

R-PHI

  Requests r-phi views, only meaningful with polar cells,
  for which this is the only available viewing method.

  In this kind of view, any solids that may have been entered
  will not be shown.

  [This is the default in polar cells.]

CUT

  Asks for a cut through the AREA in the location of the
  viewing plane. A viewing plane must therefore be defined
  when using this option - the viewing plane may of course
  be defined in the same AREA statement, but the formula for
  this plane need not be repeated if has been entered in a
  preceding AREA statement.

  The display will show the solids through which the viewing
  plane cuts, but will not show solids that are located fully
  above or below the viewing plane.

  If displaying the solids is not desired, then the X-Y, X-Z
  or Y-Z options can be used. If on the other hand all solids
  should be shown, then the 3D option should be taken.

  [CUT becomes the default if a viewing plane is defined in
  the same AREA statement, unless 3D was set previously.]

3D

  Asks for a three dimensional impression of the chamber as
  seen along an axis normal to the viewing plane. An attempt
  is made to remove partially and fully hidden parts of the
  solids. Similarly, curves are clipped to show only the parts
  that are not hidden by a solid.

  The various solids present in the cell are coloured in shades
  of their basic colour, depending on the exposure with respect
  to the light source and the viewing angle, and on the
  reflectivity and the absorption properties.

  This option is highly CPU intensive and makes use of a much
  large number of colours than usual.

  The plots consist of the following elements:

  - the 3 backmost panels, in various shades of the
    BOX-TICKMARKS fill area representation
  - the outlines of these panels, using the BOX-TICKMARKS
    polyline representation
  - the planes, in various shades of the PLANES fill area
    representation
  - the tube, in various shades of the TUBE fill area
    representation
  - the wires and conductor solids, in various shades of
    the CONDUCTORS-n fill-area representations
  - the dielectrics, in various shades of the DIELECTRICA-n
    fill area representations
  - the outlines of the wires, conductors and dielectrica
    using the OUTLINE polyline representation

plane

  In 3-dimensional field plots, plane oriented commands such as
  PLOT SURFACE, PLOT VECTOR and PLOT HISTOGRAM commands need to
  know in which plane they should operate.

  If you plan to issue field plotting commands after the AREA
  statement, then please ensure that the viewing plane crosses
  the limiting box of the area - points on the viewing plane,
  but outside the limiting box are not shown.

  For drift plots, the viewing plane merely determines the plane
  onto which the drift lines will be projected. Wires, tubes,
  planes and other materials are plotted as the cross section
  with the viewing plane.

  The VIEW argument enables you to define the viewing plane, and
  offers some control over the coordinate system in this plane.

  The viewing plane is defined by a formula in terms of the
  variables X, Y and Z that defines the points located in the plane.
  The formula should be linear in all 3 variables. No particular
  format is required, the formula is not looked at token by token,
  but evaluated at 9 points to extract the parameters of the plane.

  [The default setting is Z=0.]

plane_coordinates

  The coordinates system in the viewing plane is by default
  chosen as follows. Assume that a, b and c are not all zero so
  that a plane is defined by the formula:

  a*x + b*y + c*z = d

  Then N = (a,b,c) is a vector normal to the plane. The origin of
  the coordinates in the viewing plane is chosen to be:

  Origin = N * d / (a**2 + b**2 + c**2)

  If a and c are not both 0, then (c,0,-a) is normal to N and is
  used, after normalisation, as first coordinate. If a and c are
  both 0, then b is non-zero and (0,c,-b) is a non-zero vector
  normal to N which is used as second coordinate axis, also after
  normalisation. We call the first coordinate vector U, the second V.

  The remaining coordinate vector is obtained as the external
  product of N and the already known coordinate vector. To ensure
  the system is right-handed, we define in the first case V = N x U
  and in the second case U = V x N.

  These coordinates are chosen such that x is the first coordinate
  axis for view in the y=0 plane and y the second coordinate axis
  for the x=0 plane. They can be rotated if desired, see the "angle"
  topic.

Keyword index. Formatted on 10/11/98.