Center of a quad?

Hi!

Is anybody know how to find the exact center of a quad?

I need to write a function that create a new vertex in the middle of a quad (no diagonals) like... VertexCenter(surf, v1, v2, v3, v4).

Thanks by advance.

	centerX#=(cx1+cx2+cx3+cx4)/4
	centerY#=(cy1+cy2+cy3+cy4)/4
	centerZ#=(cz1+cz2+cz3+cz4)/4

Graphics3D 800,600,32,2
cx1#=100
cy1#=100
cx2#=160
cy2#=100
cx3#=180
cy3#=140
cx4#=100
cy4#=200
Repeat
	Cls
	cx2=MouseX()
	cy2=MouseY()
	cx3=MouseX()
	cy3=MouseY()+60
	Line cx1,cy1,cx2,cy2
	Line cx2,cy2,cx3,cy3
	Line cx3,cy3,cx4,cy4
	Line cx4,cy4,cx1,cy1
	centerX#=(cx1+cx2+cx3+cx4)/4
	centerY#=(cy1+cy2+cy3+cy4)/4
	;centerZ#=(cz1+cz2+cz3+cz4)/4
	Plot centerX,centery
	Flip
Until KeyDown(1)
End

Neat. You learn something new every day, around here.

Really great thanks mates,
didn't realise it was so easy.

Once again, this community rocks like hell...