Animate drawing of a ruled surface?

*To*: mathgroup at smc.vnet.net*Subject*: [mg122901] Animate drawing of a ruled surface?*From*: Dmichael <pwaslo at yahoo.com>*Date*: Tue, 15 Nov 2011 05:50:23 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

Hi, I want to animate the drawing of a ruled surface. So, for example, say I want to animate the drawing of a helix. I create the surface with this command: ParametricPlot3D[{u*Cos[v], u*Sin[v], (1/2)*v}, {u, -1, 1}, {v, 0, 2 \[Pi]}] Then I want an animation of the surface being drawn as the line sweeps out the surface. So I try this which shows the line but doesn't animate the drawing of the surface. Animate[ParametricPlot3D[{u*Cos[v], u*Sin[v], (1/2)*v}, {u, -4, 4}, PlotRange -> 6], {v, 0, 4 \[Pi]}] Any ideas? Thanks!