PLGRADIENT(3plplot) | PLplot API | PLGRADIENT(3plplot) |

# NAME¶

**plgradient** - Draw linear gradient inside polygon

# SYNOPSIS¶

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

# DESCRIPTION¶

Draw a linear gradient using cmap1 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 color 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 color corresponding to the independent variable of
cmap1. For more information about cmap1 (see the PLplot documentation).

Redacted form: **plgradient(x,y,angle)**

This function is used in examples 25 and 30.

# ARGUMENTS¶

*n*(**PLINT**(3plplot), input)- Number of vertices in polygon.
*x*(**PLFLT_VECTOR**(3plplot), input)- A vector containing the x coordinates of vertices.
*y*(**PLFLT_VECTOR**(3plplot), input)- A vector containing the y coordinates of vertices.
*angle*(**PLFLT**(3plplot), input)- Angle (degrees) of gradient vector from x axis.

# AUTHORS¶

Many developers (who are credited at http://plplot.org/credits.php) have contributed to PLplot over its long history.

# SEE ALSO¶

PLplot documentation at http://plplot.org/documentation.php.

November, 2021 |