Command: circle

Syntax

{<entity> =} circle

Description

Create a circle graphic entity, or a series of points forming a circle.

Parameters

• <entity>
  An entity or gstructure identifier. The circle entity will be given this name.

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.

• -ap=<num>
  Number of line approximations used when drawing or calculating the circle. If omitted, the default curve approximation def_approx is used.

• -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.

• -c=<point>
  The center of curvature. The default is the current value of graphic control, or is computed from other parameter values.

• -col=<color>
  The color of the circle. If included, this will override any color defined in the linestyle (-ls). If omitted, the value no_change is used.

• -e=<point>
  A third point on the circumference.

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

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

• -ls=<linestyle | color>
  The linestyle of the circle. This may be a linestyle or a color. If omitted, the current modeling color (def_color) is used.

• -m=<point>
  Another point on the circumference.

• -n=<direction>
  The normal to the plane of the circle. The default is up, or is computed from other parameter values.

• -op=<ident>
  A point identifier into which points along the circle are to be recorded. This option is not available when an entity is being created. If <ident> does not exist a new point array is created using current scope rules.

• -r=<num>
  The circle radius. If omitted, it is computed from other parameter values.

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

• -s=<point>
  A point on the circumference.

• -th=<num>
  The thickness of the circle. If included, this will override any thickness defined in the linestyle (-ls).

Notes

If the command has the form <entity> = circle, an entity is always created.

If the command has no entity assignment, an entity will only be created when the -op option is not used, or if the command is not within another entity creation block, e.g. lines, polygon.

All point parameter expressions are computed relative to the last computed point parameter.

Examples

Create an unnamed circle entity.

circle -c=p0, -r=500

Create a named circle entity.

entity my_circ = circle -c=p0, -s=my_point, -ls=green

Store circle points into an array (no entity created).

point cps[]
circle -s=gc, -m=(200,300,0), -e=my_point, -op=cps

Add circle points to a lines entity under creation.

lines -no_draw {
    gc, e:500
    circle -r=100, -n=e, -ap=32
}

See Also