Почему код ничего не рисует?

procedure TForm1.Button1Click(Sender: TObject);
var
xa,ya,xb,yb,xc,yc:Integer;
a,b,c:Double;
Lc,Lb:Double;
S,p,r:Double;
cx,cy,bx,by:Double;
K1,K2:Double;
x,y:Double;
 
begin
xa:=StrtoInt(edit1.Text);
ya:=StrtoInt(edit2.Text);
xb:=StrtoInt(edit3.Text);
yb:=StrtoInt(edit4.Text);
xc:=StrtoInt(edit5.Text);
yc:=StrtoInt(edit6.Text);
 
a:=sqrt((xb-xc)*(xb-xc)+(yb-yc)*(yb-yc));
b:=sqrt((xa-xc)*(xa-xc)+(ya-yc)*(ya-yc));
c:=sqrt((xa-xb)*(xa-xb)+(ya-yb)*(ya-yb));
 
p:=(a+b+c)/2;
S:=sqrt(p*(p-a)*(p-b)*(p-c));
r:=S/p;
 
Lb:=a/c;
Lc:=a/b;
 
cx:=(xb+Lc*xa)/(Lc+1);
cy:=(yb+Lc*ya)/(Lc+1);
 
bx:=(xc+Lb*xa)/(1+Lb);
by:=(yc+Lb*ya)/(1+Lb);
 
K1:=(cy-yc)/(cx-xc);
K2:=(by-yb)/(bx-xb);
 
x:=(K1*xc-K2*xb+(yb-yc))/(K1-K2);
y:=K1*(x-xc)+yc;
 
 
panel1.Canvas.MoveTo(xa,ya);
panel1.Canvas.LineTo(xb,yb);
panel1.Canvas.LineTo(xc,yc);
panel1.Canvas.LineTo(xa,ya);
 
xa:=Trunc(x-r);
ya:=trunc(y-r);
xb:=trunc(x+r);
yb:=trunc(y+r);
 
panel1.Canvas.Ellipse(xa,ya,xb,yb);
end;