1PLGRADIENT(3plplot)               PLplot API               PLGRADIENT(3plplot)
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NAME

6       plgradient - Draw linear gradient inside polygon
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SYNOPSIS

9       plgradient(n, x, y, angle)
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DESCRIPTION

12       Draw a linear gradient using colour map 1 inside the polygon defined by
13       the n points (x[i], y[i]).  Interpretation of the polygon is  the  same
14       as for plfill(3plplot).  The polygon coordinates and the gradient angle
15       are all expressed in world coordinates.  The angle from the x axis  for
16       both the rotated coordinate system and the gradient vector is specified
17       by angle.  The magnitude of  the  gradient  vector  is  the  difference
18       between  the  maximum  and  minimum values of x for the vertices in the
19       rotated coordinate system.  The origin of the gradient  vector  can  be
20       interpreted  as being anywhere on the line corresponding to the minimum
21       x value for the vertices in the rotated coordinate  system.   The  dis‐
22       tance along the gradient vector is linearly transformed to the indepen‐
23       dent variable of colour map 1 which ranges from 0. at the tail  of  the
24       gradient  vector  to  1.  at  the head of the gradient vector.  What is
25       drawn is the RGBA colour corresponding to the independent  variable  of
26       colour  map 1.  For more information about colour map 1 (see the PLplot
27       documentation).
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29       Redacted form: plgradient(x,y,angle)
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31       This function is used in examples 25,30.
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ARGUMENTS

34       n (PLINT, input)
35              Number of vertices in polygon.
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37       x (PLFLT *, input)
38              Pointer to array with x coordinates of vertices.
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40       y (PLFLT *, input)
41              Pointer to array with y coordinates of vertices.
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43       angle (PLFLT, input)
44              Angle (degrees) of gradient vector from x axis.
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AUTHORS

48       Geoffrey Furnish and Maurice LeBrun wrote and  maintain  PLplot.   This
49       man  page  was  automatically  generated from the DocBook source of the
50       PLplot  documentation,  maintained  by  Alan  W.   Irwin   and   Rafael
51       Laboissiere.
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SEE ALSO

54       PLplot documentation at http://plplot.sourceforge.net/resources.
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58                                  July, 2010               PLGRADIENT(3plplot)