Draw part of a circle

[nsbrown]

Hi all,
I need to draw a part of a circle in my program.
Is there a graphical way to define a circle to be say 60 degrees?
Or does anyone have an idea how to draw part of a circle using a loop of lines?

tnx,
Sharon

[Walt Decker]

Rad = 4 * ATN(1) / 180
Radius = 25
Cx = 50
Cy = 50
X1 = Cx
Y1 = Cy - Radius
X = 0
Y = 0
NumDegrees = 60

PRINT #WIN.GFX, "PLACE ";X1;" ";Y1
PRINT #WIN.GFX, "DOWN"

FOR I = 0 TO NumDegrees STEP 5.0
 X = Cx + Radius * SIN(I * Rad)
 Y = Cy - Radius * COS(I * Rad)
 PRINT #WIN.GFX, "LINE ";X1;" ";Y1;" ";X;" ";Y
 X1 = X
 Y1 = Y
NEXT I


[Rod]

The value of I, is the key here. The radius sets the size of the arc but I sets which parts of the circle are drawn. Try I=270 to 360, I=90 to 180

[Walt Decker]

If you want an elliptical arc provide two radii.
If you want to start the arc at some point other than zero (top of a circle) calculate the starting point from the center of the circle, e. g. :

Degrees = 60
DegreesStart = 327
X1 = Cx + Radius * SIN(DegreesStart * Rad)
Y1 = Cy - Radius * COS(DegreesStart * Rad)

PRINT #WIN.GFX, "PLACE ";X1;" ";Y1
PRINT #WIN.GFX, "DOWN"

FOR I = DegreesStart TO DegreesStart + Degrees STEP 5.0 '<--- to draw at the top
FOR I = DegreesStart TO DegreesStart - Degrees STEP -5.0 '<--- to draw at the left side

[nsbrown]

Thank you very much everyone you have helped me a lot I really appreciate it