Board index » delphi » painting circle and pieces

2004-01-30 05:10:19 PM
delphi82
Hi there,
I would like to paint a circle and a dynamic number of lines from its middle
to the circle so it looks like a cake that has been cut into the dynamic
number of pieces. How could this be done?
To start with, I divide the 360?of the circle with the number of pieces.
But how do I draw the lines to the "border" of the circle?
Thanks!
Pascal
 

OK, I have managed to get this far:
r:=ROUND(Flaeche.Height/2);
x0:=ROUND(Flaeche.Width/2);
y0:=ROUND(Flaeche.Height/2);
alpha:=ROUND(360/fDatenmodul.dsFaktoren.recordcount);
for i:=0 to fDatenmodul.dsFaktoren.recordcount do
begin
Canvas.MoveTo(x0,y0);
canvas.Pen.Width:=3;
canvas.Pen.Color:=clBlack;
case (i*alpha) of
0..90 : begin
x1:=x0+ROUND(sin(i*alpha)*r);
y1:=y0-ROUND(cos(i*alpha)*r);
end;
91..180 : begin
x1:=x0-ROUND(sin(i*alpha)*r);
y1:=ROUND(cos(i*alpha)*r)+y0;
end;
181..270 : begin
x1:=x0-ROUND(sin(i*alpha)*r);
y1:=y0-ROUND(cos(i*alpha)*r);
end;
271..360 : begin
x1:=x0+ROUND(sin(i*alpha)*r);
y1:=y0-ROUND(cos(i*alpha)*r);
end;
end;
Unfortunately, the lines are not exact where I am expecting them. There must
be an error in my algorithm...
Where??
Thanks,
Pascal
 

The goniometric functions need radians as input.
x0 := x0 + round(r * sin(i * alpha * PI / 360));
etc.
Alfred.