Command: polygon

Syntax

{<entity> = } polygon {
    <pcommand>
    ...
}

Description

Create a polygon graphic entity.

Parameters

• <entity>
  An entity or gstucture identifier.The polygon entity will be given this name.

• <pcommand>
  A command line containing either:

• a language command to be executed normally, which may or may not generate polygon vertices, or

• a series of point expressions separated by commas defining polygon vertices.

Switches

• -alph=<num>
  An alpha transparency factor between 0 and 1. A value 1 implies fully opaque, 0 means fully transparent (therefore invisible). The default is 1.

• -br=<num>
  A brightness factor between -1 and +1. A value 0 means normal, -1 means very dark (black), +1 means very bright (white). The default is 1.

• -col=<color>
  The color of the polygon edges. If included, this will override any colors defined in the line style (-ls) and the fill style (-fil). If omitted, the value no_change is used.

• -draw
  Display the entity graphics during creation. The default behavior is to suppress display until completion of the command, unless the command was typed from the keyboard.

• -ff
  Fix the fill color so that it is unaffected by subsequent modifications to the entity color.

• -fil=<fillstyle>
  The fill characteristics color of the polygon interior. If omitted, the polygon is not filled. Note: <fillstyle> can be a fillstyle, color, tile, hatchstyle or graduation.

• -fr=<num>
  Define a fragment number for the entity. If omitted the default fragment is used.

• -g=<groups>
  The graphic groups of which the entity is to be a member.

• -h
  Define this polygon as an "outer hole" polygon. It is useful to define an outer polygon as a hole when it is used merely as a container for other top-level polygons which require to be linked. Such outer hole polygons are often given a null linestyle to suppress the drawing of their edges.

• -ls=<linestyle | color>
  The line style of the polygon edge. This can be a line style or a color. If omitted, the current modeling color def_color is used.

• -par=<entity>
  The parent entity of the polygon. This is only necessary when the polygon is to be a hole within another polygon.

• -pc
  Compute the para-centroid of the polygon and make it the polygon’s origin.

• -ra=<num>
  Define a rank for the entity. If omitted, the default rank is used.

• -th=<num>
  The thickness of the polygon edges. If Included this will override any thickness defined in the line style (-ls) or hatch style (-fil).

Notes

This command always creates a graphic entity. Duplicate consecutive vertices are ignored.

The symbology of polygon egdes may be changed by using relevant assignments within the command block, e.g. def_color=blue.

During edge definition, a vector phrase beginning with a @ will indicate a n invisible edge. A phrase beginning with $ indicates a line styled edge, using line style def_ls. If neither prefix is present, the line style given by the -ls switch will be used. Warnings are given if polygon edges cross or when slivers are detected.

Examples

Create an unnamed triangular polygon entity.

polygon {gc, e:1000, w:500&n:500, r}

Create an unnamed polygon entity, whose edges are defined interactively.

polygon -col=red, -fil=green, -pc {
    pseries; # Command
    r; # Point phrase "return to start"
}

Create a named polygon entity in a command block. The polygon is a regular polygon of 2000 edges.

angle_mode = "radians"
numeric nedges = 2000, radius = 1000
numeric ang = 0, delta = 2*pi/nedges
entity bigp = polygon -fil=red {
    for i=1,nedges { #Command
        (radius*cos(ang), radius*sin(ang), 0); # Point phrase
        ang = ang + delta; # Command
    }
}

Add a circular hole to the previous polygon.

polygon -par=bigp {
    circle -c=p0, -r=250
}

See Also