# How to draw a 3D point moving along a helical path?

I have an animation for a helix being drawn in 3D but I really want to have a point on there that draws the helix. I've seen similar problems on here for 2D and I tried adapting the suggestions but I wasn't able to make anything work. I think it would be really cool to see a particle moving along this path. Any help would be greatly appreciated.

My code is as follows:

 Animate[ParametricPlot3D[{Cos[t], Sin[t], t/4}, {t, 0, u},
ImageSize -> Small, PlotRange -> {{-2, 2}, {-2, 2}, {0, 8}}], {u, 0,
30}, AnimationRate -> 3]


• You mean something like Epilog->{Point@{Cot[u],Sin[u],u/4}}? Nov 2, 2019 at 21:27
• Or this? Nov 2, 2019 at 21:33

You can add a moving point using a combination of options MeshFunctions, Mesh, and Method as follows:

Animate[ParametricPlot3D[{Cos[t], Sin[t], t/4}, {t, 0, u},
ImageSize -> Small,
MeshFunctions -> {#4 &},
Mesh -> {{u}},
MeshStyle -> Red,
Method -> {"BoundaryOffset" -> False},
PlotRange -> {{-2, 2}, {-2, 2}, {0, 8}}] /. Point -> (Sphere[#, .15] &),
{u, 10^-6, 30}, AnimationRate -> 3]


\

Note: Used ReplaceAll to change the Point primitive to Sphere.

• Awesome! Thank you so much!! Nov 3, 2019 at 2:34

Another option suitable for convenient embedding of many graphics primitives is to use Show and Graphics3D:

Animate[Module[{a},
Show[
ParametricPlot3D[a = {Cos[t], Sin[t], t/4}, {t, 0, u},
ImageSize -> Small,
PlotRange -> {{-2, 2}, {-2, 2}, {0, 8}}],

Graphics3D[{Red, Sphere[a, 0.15]}]]],

{u, 10.^-6, 30}, AnimationRate -> 3]