CIRCLE

Syntax CIRCLE [#ch,] x,y,radius [,ratio,ecc] *[;xi,yi,radiusi [,ratioi,ecci]]*
Location QL ROM

This command allows you to draw a circle of the given radius with its centre point at the point (x,y).

The positioning and size of the circle will actually depend upon the scale and shape of the specified window (default #1).

The co-ordinates are calculated by reference to the graphics origin, and the graphics pointer will be set to the centre point of the last circle to be drawn on completion of the command.

If any parts of the circle lie outside of the specified window, they will not be drawn (there will not be an Overflow Error).

If the parameters ratio and ecc are specified, this command has exactly the same effect as ELLIPSE.

This command will actually allow you to draw multiple circles by including more sets of parameters. Each additional set must be preceded by a semicolon (unless the preceding circle uses five parameters). This means that these commands are all the same:

CIRCLE 100,100,20,1,0,50,50,20
CIRCLE 100,100,20;50,50,20
CIRCLE 100,100,20:CIRCLE 50,50,20

Although the FILL command will allow you to draw filled circles on screen (in the current ink colour), you will need to include a FILL 1 statement prior to each circle if they are to appear independently on screen (this cannot be achieved when using this command to draw multiple circles!). If this rule is not followed, then any points which lie on the same horizontal line (even though they may be in different circles) will be joined.

Example

Try the following for an interesting effect:

100 WINDOW 448,200,32,16: MODE 8
110 PAPER 0: CLS
120 SCALE 200,-100,-100
130 INK 4:CIRCLE -50,-50,5
140 FOR i=1 TO 350
150   INK RND(7): FILL 1
160   CIRCLE_R 5-(i MOD 10),15-(i MOD 30),20
170 END FOR i

CROSS-REFERENCE

Please refer to ELLIPSE for further information on the ratio and ecc details.