| .CIRCLE Statement Details. |
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| CIRCLE Statement Details |
|
| Syntax |
| CIRCLE [STEP] (x,y),radius[,[color][,[start][,[end][,aspect]]]] |
| |
| Argument Description |
| STEP The STEP option specifies that x and y are offsets |
| relative to the current graphics cursor position. |
| x,y The x and y coordinates for the center of the circle |
| or ellipse. |
| radius The radius of the circle or ellipse in the current |
| coordinate system. |
| color The attribute of the desired color. The default color is |
| the foreground color. See the COLOR statement details and |
| the SCREEN statement details for more information on |
| how to specify a color in different display screen modes. |
| start, end The start and end angles, in radians, for the arc to |
| draw. The start and end arguments are used to draw |
| partial circles or ellipses. The arguments may range |
| in value from -2PI radians to 2PI radians, where |
| PI= 3.141593. The default value for start is 0 radians. |
| The default value for end is 2PI radians. |
| |
| If start or end is negative, then CIRCLE draws a |
| radius to that point on the arc and treats the angle |
| as if it were positive. |
| |
| The start angle can be less than the end angle. If |
| you specify end but not start, the arc is drawn from |
| 2PI to end; if you specify start, but not end, the |
| statement draws an arc from start to zero. |
| |
| aspect The aspect ratio, or the ratio of the y radius to the |
| x radius. The default value for aspect is the value |
| required to draw a round circle in the screen mode. |
| This value is calculated as follows: |
| |
| 4 * (ypixels/xpixels)/3 |
| |
| where xpixels by ypixels is the screen resolution. |
| For example, in screen mode 1, where the resolution |
| is 320 x 200, the default for aspect would be: |
| |
| 4 * (200/320)/3, or 5/6. |
| |
| If the aspect ratio is less than one, radius is the |
| x radius. If aspect is greater than one, radius is |
| equal to the y radius. |
| |
| To draw a radius to angle 0 (a horizontal line segment to the right), |
| do not give the angle as -0; use a very small nonzero value instead |
| as shown: |
| |
| ' Draws a pie-shaped one-quarter wedge of a circle: |
| SCREEN 2 |
| CIRCLE (200,100),60,,-.0001,-1.57 |
| |
| You may omit an argument in the middle of the statement, but you must |
| include the argument's commas. In the following statement, the color |
| argument has been omitted: |
| |
| CIRCLE STEP (150,200),94,,0.0,6.28 |
| |
| If you omit the last argument, you do not include the commas. |
| |
| The last point that CIRCLE references, after drawing, is the |
| center of the ellipse or circle. You may use coordinates that are |
| outside the screen or viewport. |
| |
| You may show coordinates as absolutes, or you may use the STEP |
| option to show the position of the center point in relation to the |
| previous point of reference. For example, if the previous point of |
| reference is (10,10), then the following statement causes a circle |
| to be drawn with radius 75 and center offset 10 from the current x |
| coordinate and 5 from the current y coordinate. The circle's |
| center is (20,15). |
| |
| CIRCLE STEP (10,5), 75 |
| |
