Problem outputting arc to dxf file

[timc]

I have written a script that outputs simple 2D drawings to a dxf file, but I am having some trouble with arcs. Sometimes they output fine, other times they are either facing the wrong way or in the wrong location.

This is the code I'm using to output arcs. The start_angle of ArcCurves was always 0.0 so I created the get_new_angle function to calculate the angle of a line from the center of the arc to the start point, I use that as the start_angle and add it to end_angle.

Any help with this would be appreciated, Thanks

def dxf_output_arc(curve, layername)
#curve is an ArcCurve object
#layername is the name of the layer the object is on
	points = curve.center
	new_angle = get_new_angle(points, curve.vertices[0].position)
	$dxf_file.puts( "  0\nARC\n8\n"+layername+"\n")
	$dxf_file.puts(10.to_s+"\n"+(points.x.to_f * $conversion_factor).to_s)#x
	$dxf_file.puts(20.to_s+"\n"+(points.y.to_f * $conversion_factor).to_s)#y
	$dxf_file.puts(30.to_s+"\n"+(points.z.to_f * $conversion_factor).to_s)#z
	$dxf_file.puts(40.to_s+"\n"+(curve.radius.to_f * $conversion_factor).to_s)#radius
	$dxf_file.puts(50.to_s+"\n"+new_angle.to_f.to_s)#start_angle
	$dxf_file.puts(51.to_s+"\n"+((curve.end_angle.degrees + new_angle).to_f).to_s)#end_angle
end

def get_new_angle(center, point)
#This function returns the angle of a line
	return Math;;atan(((center.y.to_f - point.y.to_f)/(center.x.to_f - point.x.to_f))).to_f.degrees.abs
end

[thomthom]

I wouldn't rely on start_angle to always be 0.0. I think I remember doing some work with arcs where I found cases where the start_angle where not 0.0.

[timc]

I could change it so it recalculates the end_angle as well, that way I would not have to worry what SketchUp says the angle is. But I think I have bigger issues than that.