Is it very difficult to make an extending line on a surface (angled)?

I saw an animation in which lines were growing or flowing on a long surface, sort of like a wall on a corridor. The surface or corridor was not a realistic corridor, just a long rectangular tunnel with has angled corners and some rectangular things on the wall, sort of like the following.

On a flat surface I could just put a rectangle and set an animation on the scale property, but what if there are corners and other extruding things? Is there an easy way to do it, or do I have to create separate line animations on each segmented flat surface?

It’s fairly simple:

  • Go in Edit more and make an edgeloop like this:

  • Then select part of the edgeloop you need, duplicate it (Shift+D). Now rightclick so you won’t move the edge.

  • The edge is still selected. Press p (Seperate) by selection. This Edge will now be a new object.

  • Go out of Edit mode, so you go back to Object mode. And then you select that Edge

  • In the 3D viewport in the menu, you click: Convert > to Curve from Mesh

  • Then you extrude the edge (in properties panel > Object Data Properties > Geometry) and you might need a solidify modifier and maybe offset to shape it the way you want.

  • Then to animate the curve: you go in the properties panel > Object Data Properties > Geometry > Bevel Start. And you animate the Bevel Start and/or Bevel End

I tried it out:
(Done with the EEVEE Production Suite of course).

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Thanks, but can you explain the animation step more? How can I set the animation on Bevel Start? I tried it but nothing moves.

extending.blend (123.4 KB)

@loserlearningblender One of the problems was that you didn’t apply scale with Ctrl+A. Another problem might be that the curve was closed, but not sure. Anyway, here the blendfile where it is working:
extending2.blend (133.7 KB)

Seems like its being closed was the cause of not working. I deleted one segment of the curve, and then it worked. By the way, why does “Bevel” work this way? Isn’t bevel is for rounding a corner? How come it increases the line?