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 thenpoints (x[i],y[i]). Interpretation of the polygon is the same as forplfill(3plplot). The polygon coordinates and the gradient angle are all expressed in world coordinates. The angle from thexaxis for both the rotated coordinate system and the gradient vector is specified byangle. The magnitude of the gradient vector is the difference between the maximum and minimum values ofxfor 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 minimumxvalue 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). Redacted form:plgradient(x,y,angle)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.

**SEE** **ALSO**

PLplot documentation at http://plplot.sourceforge.net/resources. February, 2012 PLGRADIENT(3plplot)