Animate Extrusion and Edit Processes

Hey, NewB here. Apologies if I’ve missed something obvious, but I’d like to animate the extrusion process of simple poly’s into more complex shapes. Keyframes does not seem to save this data.

How would I animate the sides of a Cube extruding over time?

Any pointers or links to relevant tutorials would be greatly appreciated.

P.S. - The Build Modifier is close, but I am looking for a smooth effect, and this is not it.

I think shape keys would do the trick. The geometry already has to be in place, but at the beginning of the “extrude” (the basis) the face to be extruded would be exactly on top of the face being extruded (which wouldn’t really exist, just the corner vertices.) The key would be set with the face moved out in the direction of the extrude. If the geometry in complicated or the animation involves multiple extrudes, you should consider making the extruding faces into vertex groups, to make it easier to select them when it comes time to move them around.

I will try exploring shape keys. How would you accomplish this with vertex groups?

I want to animate from a simple cube into a relatively complex shape.

Ok, commands like Edit and Spin seem to work with Shape Keys, but extrusion information is not stored with shape keys. I wonder why this is?

Am I missing something?

Based on my [admittedly not completely thorough] understanding of shape keys, it works on a fixed, known, number of vertices. That is, you can key the location of existing vertices with shape keys, but it does not account for the creation of new vertices.

Perhaps if you explained what you’re trying to do a little bit more specifically, then we can provide you with an alternate solution.

For example, let’s say I wanted to grow a simble cube into a cross, and animate it smoothly instead of jumping by each face as seen with the “build” function. This would be the simplest application of what I am trying to do.

Im quite interested in evolving geometries, and eventually I’d like to explore forms that evolve from simplicity to deepending levels of complexity (and back again).

Shape keys definitely wont do it.

Well, since shape keys definitely won’t do it, this couldn’t possibly be what you’re trying to do. Perhaps a better example would make more clear what you are trying to accomplish?

Yes, that is what I am trying to do. Sorry for not understanding, but how did you record the extrusion with shape keys? Mind explaining? Or perhaps point out what I am doing wrong?

I did not record the extrusion with shape keys. I animated the extrusion with shape keys. That’s basically what you’re missing. A timeline.

Set your screen up with a Buttons window set to Edit panels, a 3D window set to camera, and an Action Editor window.

Add a cube. Select the top face. Extrude it but don’t move it. Escape to end the extrude. You now have double vertices on the top face. While the new vertices are still selected, make them into a vertex group called, say, top face.

Switch to Object mode. In the Shapes panel, Add new shape. You should get a shape called “basis” and a “slider” title shows up in the Action Editor. Click on the arrowhead, the slider column will open, but it’s empty at this point.

Select Add shape key again. This time you’ll get some more controls. Name the key and fill in the Vertex group with the name of the vertex group created earlier. There’s a couple of ways to set the initial key, but the simplest is to click on the slider’s number 0.00 in the Action Editor, and reenter the number 0. A key should show up in the Action editor.

Now we do some animation. Move the timeline out to, say, frame 30. (drag the green line out to 30, or set the Animation Frame counter in the Button window header.)

In the 3D window, switch to edit mode, use the vertex group “select” function to select the top face (this will be more useful as the shapes get more numerous or more complicated), and move it up along the z axis. Click on the Top Face slider number again, but this time type in 1. A new key should appear under the green timeline at frame 30. Set the 3D window back to object mode. The object should retain it’s new shape.

Now you can drag the green timeline between frame 1 and frame 30, and the object will change from the 0.00 shape (a cube) and the 1.00 shape, a tall rectangular prism.

With the cursor in the 3D window, Alt a will animate the object. (Escape ends the animation)

More: drag the timeline out to frame 60, and slide the slider back to 0. Now the face will grow and shrink again. To make it loop, go into the render panels (F10) and set the end value in the anim panel to 60.

More: you can repeat this process with a different face, or you can set up many extruded faces and vertex groups all at the same time, and then just add new shape keys, but either way: SET THE SHAPE KEY BACK TO BASIS before you add another new shape key. Given your goals, you may want to experiment with starting a new shape key based on something other than the basis key. If you do, and you figure out how to control it, write it up and post it either here or in tutorials. (That’s your fee for getting all this good advice.)

This works well, but I dont seem to be able to extrude new vertices that have been created by previous extrudes.

Anyways, thanks a heap for the help with the basic function.

You won’t be able to, unless all the extrudes are present in the beginning and you just wait to activate them. This could get very complicated and confusing. On the other hand, this might be the perfect time to learn about animation tricks: do two takes. Start your second extrude using the extruded cube as your base model, and do a completely new animation, only this time set it to start where the previous animation ended (plus one frame). Then when you’re done rendering, pull all the stills into the sequencer and make a single video. As long as you don’t move the camera or play with scale between takes, you’ll be fine.

You just need to think these things through. Don’t expect Blender to do all the work.