DCL:GRPH2:UGPACK :Vector Field Display Routines
The UGPACK is a subroutine package for drawing 2-D vector fields. At the present, processes such as the scaling of vector length are performed in the V-coordinate and the vector is drawn in the V-coordinate, so this package can only be used for Cartesian linear coordinates (transformation function numbers ITR = 1-4).
In this package, a vector is drawn using the arrow sub-primitives of GRPH1. This
package only draws a vector field, and does not draw the outer frames such as
the coordinate axes.
Below are the subroutines a user will be using in the UGPACK.
Information concerning the grid- point coordinates are handled by UWPACK. (See
Chapter 11.)
When you want a quick look of the vector data given on 2-D grid points, simply
call UGVECT. When this call is made, evenly-spaced grid points are set to
fill the whole area of the current window, and the scaling of vector lengths
will be performed automatically.
If the grid points are not evenly spaced, specify the coordinate values of the
grid points by calling UWSGXA (X direction)/ UWSGYA (Y-direction) before calling UGVECT. Or,
when you wish to set evenly-spaced grid points in only a part of the window,
specify the minimum and maximum value of the gird points using UWSGXB (X direction)/
UWSGYB (Y-direction).
You may also specify the internal variables to change the scaling factor or to
draw a unit vector. (An "internal variable" refers to an internal
variable that is handled by
UGpGET/UGpSET, unless specified
otherwise.)
Copyright (C) 2000 GFD Dennou Club. All rights reserved.