Animate Extrusion

Question

I would like to animate the building of a House, similar to The Sims gameplay if you are familiar with that. That means I need to animate the extrusion of the wall(s). Is there a way to accomplish that in blender?

My plan was to use a plane in combination with a solidify modifier, and animate the extrusions along a grid, but as far as I know you can't keyframe extrusions, or add new vertices during an animation.

https://www.youtube.com/watch?v=2OYr-uAzZb4&t=193s <---- some reference. The first minute is the only important content.

Thanks in advance

Answer 1

Shape keys can be used to animate the vertices of a mesh. You will need a shape key for each step of the animation, so I'm going to use 2 shape keys to animate an L shaped room. A square room would only need 1 shape key. I'm using a solidify modifier here to reduce vertices needed to animate.

In Object Mode, under Object Data properties > Shape Keys, add the number of shape keys needed, as I previously mentioned, I'll be adding 2 to animate this in 2 steps. Make sure each shape key is Relative To the previous one to make animating simpler.

Select the first shape key and go into Edit Mode. Move your vertices to the first step of animation. Go back into Object Mode, select the second shape key, then go back into Edit Mode to make the next step of animation.

Now you can animate the shape keys to adjust the extrusion of the walls.

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Answer 2

One solution could be to use a Boolean modifier.

Add a large enough cube to your scene to envelope the walls and add a Boolean modifier to the walls, then set it to subtract the cube (I believe it's Difference but can't check right this second.)

Then, animate your cube moving up slowly.

This may create graphical glitches as your topology will be interrupted, but it could be a good starting block. If your walls are made of simple geometry, this may not even be an issue. Hope that helps!

Answer 3

I use shapekeys for this.

Create your object and do the extrusions so that you have all of the vertices. Shapekeys don't work if you add vertices.

In Object mode add two shapekeys. The first one will be your fully extruded wall. Select the second one and enter edit mode,.

Now move all of the extruded vertices so that they are exactly aligned to the vertices they were extruded from. This will give the appearance that you haven't done the extrusion.

You can animate the second shapekey's Value setting. By starting at 1 and going to 0, you effective animate the extrusion.