Drawing a percentage circle with surface.DrawPoly

[MysteryPancake]

So, I'm trying to make a GTA-director-mode-style recording addon (yes, I know, a ton of work and probably extremely painful) and I was trying to replicate the 'recording' circle.
I slightly modded the wiki's drawpoly example that creates a circle (pretty terribly because I'm atrocious at maths), and it seems okay, except there is a slight gap (about one or two segments) when the circle gets drawn. How would I fix this and draw it in a more proper way?

local Tex_white = surface.GetTextureID( "vgui/white" )

local function DrawPercentageCircle( x, y, radius, seg, progression )
	local cir = { [1] = { x = x, y = y } }
	local cir2 = { [1] = { x = x, y = y } }

	for i = 0, seg do
		local a = math.rad( ( i / seg ) * -360 )
		cir[#cir+1] = { x = x - math.sin( a ) * radius, y = y - math.cos( a ) * radius }
	end

	for i = 0, progression do
		table.insert( cir2, cir[next(cir)+1] )
		table.remove( cir, next(cir)+1 )
	end

	surface.SetTexture( Tex_white )
	surface.SetDrawColor( 255, 0, 0, 255 )
	surface.DrawPoly( cir )
	surface.SetDrawColor( 0, 0, 0, 255 )
	surface.DrawPoly( cir2 )
end

[zamboni]

-snip-

I'm just bad at math, one minute it works, another it doesn't. I'll do more testing.

[MysteryPancake]

Bump, anyone know?

[Arizard]

function surface.DrawSector(x, y, r, ang, rot)

	local segments = 360
	local segmentstodraw = 360 * (ang/360)
	rot = rot* (segments/360)
	local poly = {}

	local temp = {}
	temp['x'] = x
	temp['y'] = y
	table.insert(poly, temp)

	for i = 1+rot, segmentstodraw+rot do
		local temp = {}
		temp['x'] = math.cos( (i*(360/segments) )*(math.pi/180) ) * r + x
		temp['y'] = math.sin( (i*(360/segments) )*(math.pi/180) ) * r + y

		table.insert(poly, temp)
	end
	
	surface.DrawPoly(poly)

end

r for radius in units, ang (0-360) for angle of the sector in degrees, rot for the rotational offset of the sector in degrees.

[MysteryPancake]

[QUOTE=Arizard;48443655]

function surface.DrawSector(x, y, r, ang, rot)

	local segments = 360
	local segmentstodraw = 360 * (ang/360)
	rot = rot* (segments/360)
	local poly = {}

	local temp = {}
	temp['x'] = x
	temp['y'] = y
	table.insert(poly, temp)

	for i = 1+rot, segmentstodraw+rot do
		local temp = {}
		temp['x'] = math.cos( (i*(360/segments) )*(math.pi/180) ) * r + x
		temp['y'] = math.sin( (i*(360/segments) )*(math.pi/180) ) * r + y

		table.insert(poly, temp)
	end
	
	surface.DrawPoly(poly)

end

r for radius in units, ang (0-360) for angle of the sector in degrees, rot for the rotational offset of the sector in degrees.[/QUOTE]

Thanks for this, but drawing a circle with a 360 radius looks like it would if the radius was 359. Any ideas why?