Provided by: plplot-doc_5.9.9-2ubuntu2_all #### NAME

```       plgradient - Draw linear gradient inside polygon

```

#### SYNOPSIS

```       plgradient(n, x, y, angle)

```

#### DESCRIPTION

```       Draw  a  linear  gradient  using  colour  map 1 inside the polygon defined by the n points
(x[i], y[i]).  Interpretation of the polygon is the  same  as  for  plfill(3plplot).   The
polygon  coordinates  and  the gradient angle are all expressed in world coordinates.  The
angle from the x axis for both the rotated coordinate system and the  gradient  vector  is
specified  by  angle.   The magnitude of the gradient vector is the difference between the
maximum and minimum values of x for the vertices in the rotated  coordinate  system.   The
origin  of  the  gradient  vector  can  be  interpreted  as  being  anywhere  on  the line
corresponding to the minimum x value for the vertices in the  rotated  coordinate  system.
The distance along the gradient vector is linearly transformed to the independent variable
of colour map 1 which ranges from 0. at the tail of the gradient vector to 1. at the  head
of the gradient vector.  What is drawn is the RGBA colour corresponding to the independent
variable of colour map 1.  For more  information  about  colour  map  1  (see  the  PLplot
documentation).

This function is used in examples 25,30.

```

#### ARGUMENTS

```       n (PLINT, input)
Number of vertices in polygon.

x (PLFLT *, input)
Pointer to array with x coordinates of vertices.

y (PLFLT *, input)
Pointer to array with y coordinates of vertices.

angle (PLFLT, input)
Angle (degrees) of gradient vector from x axis.

```

#### AUTHORS

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

```

#### SEEALSO

```       PLplot documentation at http://plplot.sourceforge.net/resources.