Command: arc

Syntax

{<entity> = } arc

Description

Create an arc graphic entity, or a series of points forming an arc.

Parameters

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

Switches

• -a=<num>
  The angle subtended by the arc. The measure used is the current angle units (angle_mode). If omitted, it is computed from other parameter values.

• -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 arc. If omitted, the default curve approximation value 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 arc 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 arc. If included, this will override any color defined in the linestyle (-ls). If omitted, the value no_change is used.

• -e=<point>
  The arc end point. The default is the current value of graphic control, or is computed from other parameter values.

• -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.

• -h=<direction>:<num>
  The general direction and height of the arc segment from the chord.

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

• -m=<point>
  A point anywhere along the arc between the start and end points.

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

• -o=A|C
  The orientation of the arc: C for Clockwise, or A for counterclockwise (the default).

• -op=<ident>
  A point identifier into which points along the arc 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 arc 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>
  The arc start point. The default is the current value of graphic control, or is computed from other parameter values.

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

Notes

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

If the command has no entity assignment, then an entity will be created only if the -op option is not used, or 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 arc entity (180 degree sweep).

arc -s=p0, -m=e:100&n:100, -e=e:100&s:100, -col=red

Create a named arc entity (90 degree sweep).

entity my_arc = arc -c=p0, -s=e:100, -a=90, -o=a

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

point arcps[]
arc -s=gc, -e=e:5000, -h=n:150, -op=arcps

Add arc points to a face entity under creation.

polygon -no_draw {
    gc, e:1000, n:200
    arc -e=n:600, -r=300, -o=c, -ap=32
    n:200, w:1000, r
}

See Also