Draw an Arc

Using this option an arc may be drawn on the current buffer. The arc will be drawn so that it appears circular on the physical screen. It will not, however, be circular in pixel coordinates.

Cursor Positioning: Locate start of arc

The cursor submenu is invoked to enable the user to specify the starting position of the arc. See [H Help] within the submenu for details on how to use the cursor facility.

Cursor Positioning: Locate centre of arc The cursor submenu is invoked for a second time to locate the centre of the arc.

Angle (-360 to 360 degrees) ?

This entry specifies the angle through which the arc is to be drawn.

Aspect ratio (0 => circle in world coordinates) ?

This entry specifies the aspect ratio (relative to a default world aspect ratio) between the vertical and horizontal length scales. A value greater than one produces a tall, thin ellipse, while less than one produces a lower, flatter ellipse. The value 0.0 will produce a circle in true world coordinates.

Use what intensity ? This entry specifies the intensity to which the pixels on the arc are to be set, or alternatively the bit mask to be used to determine their intensity.

Set, And, Or or Xor intensity ? The choice here determines if the pixels are to have their intensity set (<S>) to the specified value, or if the specified value is to be used in a logical AND (<A>), OR (<O>) or exclusive or (XOR; <X>) operation.

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DigImage User Documentation

Stuart Dalziel, last page update: 19 February 1996