func drawOrientedLine(gc *draw2d.ImageGraphicContext, x, y float64, theta float64, r float64) {
c := math.Cos(theta)
s := math.Sin(theta)
gc.MoveTo(x-r*c, y-r*s)
gc.LineTo(x+r*c, y+r*s)
gc.Stroke()
}
func drawOrientedLine(gc *draw2d.ImageGraphicContext, x, y float64, theta float64, r float64) {
c := math.Cos(theta)
s := math.Sin(theta)
gc.MoveTo(x-r*c, y-r*s)
gc.LineTo(x+r*c, y+r*s)
gc.Stroke()
}
