This is a tricky one. I'm trying to show the flow of an injection molding. So I animated a curve to show the flow in 2 dimensions. But would like to see the flow in 3D. Not a simulation, just illustrating where the material goes. I'm just trying to show, for those that don't understand 3 dimensions that well, that you can inject in one point, and the material evenly (if your tooling is awesome) grows out to fill the object.
You can bend a layer, yay. You can extrude a layer, yay. You can not bend an extruded layer. I only really need a 1/2 to 2/3rd cutaway of the cup to illustrate how the thing fills up.
One Terribly slow way I thought of was to extrude the line animation just a little. Then duplicate it about 100 times with an expression that just says "index * -2" Adjust the 2 to however much is needed to fill that space. I tried that. It looks ok, but is Crazy slow.
I also have 3dsMax, but since I rarely use it, I can't think of a great way of accomplishing this. It's a cup, yes, but it Does go back on itself a little. So I can't just animate a slice modifier. And there isn't even a great tool under loft. The "cheat" to have a loft grow is to animate the scale modification of it. It's really crappy. 3dsmax is kind of garbage. It's ok at a few things, and hasn't been updated in over 10 years for the rest.
For now, I've settled on doing it in 3dsMax, but I'm not happy with the solution, so I'm still asking you folks. I'll do a revolve of my shape, then animate a black and white map for opacity. The downside here is that I can't cap that. So it will "fill" the walls of my cup, but it will appear hollow. The walls are pretty thin, so I think it might be "good enough."
I'm a perfectionist sometimes, and this one is killing me.
It seems like it should be just so simple. The geometry isn't complex. The animation isn't complex.....if there's a tool to do it.
Just to be clear. Imagine you designed a cup/vase. You want to show it "growing" from the bottom point and filling it's body.