&FIELD: AREA
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.]
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.]
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]
Requests y-z views.
In this kind of view, any solids that may have been entered
will not be shown.
[X-Y is default]
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.]
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.]
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
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.]
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.