Fill a part of an ellipse
xfarc(x,y,w,h,a1,a2)
:x,y,w,h four real values defining a rectangle. : :a1,a2 real values defining a sector. :
xfarc fills a part of an ellipse contained in the rectangle (x,y,w,h) (upper-left point, width, height), and in the sector defined by the angle alpha1 and the angle alpha1+alpha2. alpha1 and alpha2 are given respectively by a1/64 degrees and a2/64 degrees. This function uses the current color and user coordinates.
If a2 is equal to 360*64, a complete circle will be drawn.
// isoview scaling
`plot2d`_(0,0,-1,"031"," ",[-2,-2,2,2])
xfarc(-0.5,0.5,1,1,0,90*64)
`xset`_("color",2)
xfarc(0.5,0.5,1,1,0,360*64)