Name: PGCONF
Purpose: fill between two contours
Category: GRAPHICS
File: pgplot.src
Author: T.J. Pearson
Use: see description below.
Description:
SUBROUTINE PGCONF (A, IDIM, JDIM, I1, I2, J1, J2, C1, C2, TR)
INTEGER IDIM, JDIM, I1, I2, J1, J2
REAL A(IDIM,JDIM), C1, C2, TR(6)
Shade the region between two contour levels of a function defined on
the nodes of a rectangular grid. The routine uses the current fill
attributes, hatching style (if appropriate), and color index.
If you want to both shade between contours and draw the contour
lines, call this routine first (once for each pair of levels) and
then CALL PGCONT (or PGCONS) to draw the contour lines on top of the
shading.
Note 1: This routine is not very efficient: it generates a polygon
fill command for each cell of the mesh that intersects the desired
area, rather than consolidating adjacent cells into a single polygon.
Note 2: If both contours intersect all four edges of a particular
mesh cell, the program behaves badly and may consider some parts
of the cell to lie in more than one contour range.
Note 3: If a contour crosses all four edges of a cell, this
routine may not generate the same contours as PGCONT or PGCONS
(these two routines may not agree either). Such cases are always
ambiguous and the routines use different approaches to resolving
the ambiguity.
Arguments:
A (input) : data array.
IDIM (input) : first dimension of A.
JDIM (input) : second dimension of A.
I1,I2 (input) : range of first index to be contoured (inclusive).
J1,J2 (input) : range of second index to be contoured (inclusive).
C1, C2 (input) : contour levels; note that C1 must be less than C2.
TR (input) : array defining a transformation between the I,J
grid of the array and the world coordinates. The
world coordinates of the array point A(I,J) are
given by:
X = TR(1) + TR(2)*I + TR(3)*J
Y = TR(4) + TR(5)*I + TR(6)*J
Usually TR(3) and TR(5) are zero - unless the
coordinate transformation involves a rotation
or shear.
Updates: Oct 16, 1998: JPT automatically extracted from source.