# How to make an object appear/visible along a path

I want to animate a logo. I have this hexagon following a path and want the elllipse to appear after the hexagon passed this specific point of the path (making it look like the hexagon leaves a tail).

I tried several ways with the build modifier (including sorting elements).

I got it done with the upper right part of the ellipse, by seperating the ellipse in two parts. I am not sure if I should continue splitting the whole ellipse or if there is a better way to achieve what I want. I did not find any solution to my problem on the internet.

I think another approach would be: Creating an invisible box around the hexagon and make the ellipse appear after it passed through the invisible box. Comparable to this: How to make one object gradually disappear as it passes through another object But I am not sure, because the ellipse would enter the box on one side and leave it through anoter side.

Thanks

• You can do this with Dynamic Paint", you would make the plane a canvas and make the hexagon a brush. Aug 26, 2019 at 18:38
• Oh, thanks I will try that Aug 26, 2019 at 18:39
• I think the other answers give a better result, but for completeness you can order the Vertices for the Build Modifier via the Mesh->Sort menu.
– rob
Aug 27, 2019 at 10:19

To keep it simple, you might consider just using the native properties of Blender curves.

Note that in this example, the path-curve is not cyclic. It's made by converting a mesh ( a circle, scaled in Edit Mode in Y ) with one of its vertices V ripped, then converted to a curve with two ends at the same place.

• A curve can have a renderable bevel profile .. either its own, (a circle with variable resolution) or another curve you assign for the purpose, which will be swept along its local Z.
• The profile can be tapered along its length, using another curve
• The start and end points of the bevel along the curve can be set, and animated. So the curve can be made to 'grow' along its length.
• The taper can be mapped either to the entire curve, or just the part which is beveled.

The illustration shows a curve, its taper, and its profile.

Your hexagon can be given a Follow Path constraint along the main curve, with its 'Offset' animated in sync with the curve's Bevel End setting.

..or maybe with the taper mapped to the beveled section:

If your using the timeline and insert keys for example LocationRotationScale keys you might want to move the beginning of your ellipse animation key further down the timeline or the key that shows the ellipse appearing on screen(because it may not be the first key), so the the start of the ellipse appears later and move and transform any other middle keys in respect to scale of any other keys of the ellipse, the end animation seems fine so you do not have to move the last key