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-
- 5.7.1 DRAW POLYGON
-
-
- The DRAW POLYGON command is used to define a closed polygon which can be
- filled with a solid colour or a patternfill. A single polygon entity may
- consist of up to 64 separate polygons, one main polygon and 63 sub-polygons.
- Sub-polygons can be used to define inner boundaries within the main polygon
- that act as 'holes' and will be excluded from the fill.
-
- If none of the font modifiers are used, the polygon will be filled with its
- layer dependent colour.
-
-
- COMMAND FORMAT ( except for PARALLEL )
-
- #DRAW POLYGON [modifiers] :Loc x1 x2 ... xn [:Loc x1 ... xn] [CR]
- Loc ...
-
- The first set of locations entered define the main polygon boundary. If this
- set of locations is delimited with a colon, then a sub-polygon boundary
- definition can be entered. Futher sub-polygon boundaries may be entered
- until a return is used to terminate the last boundary location list. When
- the polygon has been created, a second polygon entity can be defined in the
- same way. To terminate the command, a return should be entered at the 'Loc'
- prompt which appears when the previously defined polygon has been created.
-
- Polygons can somtimes be required to be drawn using existing entities to
- define the boundary of the area to be filled. To create a polygon boundary
- using existing entities, the IDENTS point on entity modes - CHAIN, GENERATE,
- END, MID, ORG and NEAR - can be used to generate the required boundary. For
- more information on this subject see the documentation for IDENTS or use the
- command:
-
- #HELP MANUAL IDENTS LOCS
-
- ( See figs. 5.46 to 5.48 ).
-
-
- MODIFIERS
-
- LAYER Requires a layer number. This will override the current
- active layer.
-
- DEPTH Requires a depth number. This will override the current
- active depth.
-
- PARALLEL Format:
-
- #DRAW POLYGON PARALLEL [value] :Ent x1 :Loc x2 :Ent ...
-
- Will draw a polygon parallel to an exsiting polygon. 'x1'
- identifies the existing polygon.
-
- 'x2' is used to define on which side of the existing polygon
- to draw the new polygon boundary. If a value is entered after
- PARALLEL, the new polygon boundary will be drawn at the
- specified distance from the existing polygon. ( See fig. 5.49
- ). If no value is entered, the distance is derived as the
- distance between 'x2' and the nearest side of the existing
- polygon.
-
- In PARALLEL mode, all sub-polygons are defined in the same
- way.
-
- RECTANGLE Will draw rectangular polygons. Two locations are entered
- for each sub-polygon, these define the extents of the
- rectangle. ( See fig. 5.50 ).
-
- In RECTANGLE mode, all sub-polygons are defined in the same
- way.
-
- The following modifiers all define alternative methods for filling the
- polygon. The 4 main types of fill are defined with the modifiers COLOURFILL,
- PATTERNFILL, HALFTONE and SHADOW.
-
- COLOURFILL Requires a colour number in the range 0 to 7. This indicates
- that the polygon will be filled with a specific colour and
- not the layer dependent colour.
-
- .HALFTONE This modifier will 'halftone' the colour fill by applying
- a mask which lets the background colour show through at every
- second pixel in the filled area.
-
- .OUTLINE Will outline the polygon with the layer dependent colour.
-
- PATTERNFILL Requires the name of a patternfill previously defined with
- the DEFINE PATTERNFILL command. The polygon area will be
- filled with the named patternfill.
-
- The following modifiers only apply to patternfills that
- were originally defined using colour 1 only. ( See the
- command DEFINE PATTERNFILL ).
-
- .COLOUR Requires a colour number in the range 0 to 7. The colour
- specified will be used as the 'foreground' colour for the
- patternfill overriding the default layer dependent colour.
-
- ..BACKGROUND The background of a patternfill is normally filled with the
- background colour, colour 0. This modifier when used with
- COLOUR will fill the background of the patternfill with the
- layer dependent colour.
-
- .OUTLINE Will outline the patternfilled polygon with the layer
- dependent colour.
-
- .TRANSPARENT If this modifier is used, instead of filling the background
- of a patternfill with a solid colour, the background will be
- made transparent. This will allow any graphics 'beneath' the
- patternfill background areas to show through.
-
- .MASK Specifies that the patternfilled polygon is to be used as a
- mask. All background areas of the patternfill will be filled
- with the background colour blotting out any graphics beneath.
- The patterned areas will become transparent allowing any
- graphics beneath these areas to show through.
-
- HALFTONE This modifier will 'halftone' a solid colour fill by applying
- a mask which lets the background colour show through at every
- second pixel in the filled area.
-
- SHADOW Defines a SHADOW polygon. A shadow polygon is a mask used to
- block out every second pixel in the polygon area. The mask
- is arranged:
-
- * * * * * * *
- * * * * * * *
- * * * * * * *
- * * * * * * * * = pixel
-
- Every 'on' position in the mask will be set to the background
- colour. Every 'off' position will allow whatever graphics are
- beneath the polygon area to show through.
-
- ATTRIBUTE Used to enter one or more attributes associated with this
- entity. For a full description of the ATTRIBUTE option, see
- the documentation for the command ADD ATTRIBUTE.
-
-
-