# How to do a "reverse explosion" effect?

I’m trying to create an animation in which a large structure is built by a number of smaller cubes that fly-in and land in their final positions. E.g. I want a large cube to appear as a result of a bunch of smaller cubes flying in. I’ve been experimenting with the “build” effect, trying to use halos that are cubes, but so far no luck. Has anyone done something similar? I’d be grateful for any ideas/suggestions.

NB - I’m a relative newbie to blender, though I’m quickly getting to understand it.

You could take a look at this:

https://blenderartists.org/forum/viewtopic.php?t=28745

I havn’t tried it, but the avi shows a mesh exploding, and then rebuilding.

Maybe it will help.

You could start with a cube, then have the individual pieces separate and fly apart. Then, run the time IPO backwards to get it to assemble.

The Time-IPO is the secret. Normally this IPO is a diagonally upward-sloping line: moving from 0.0 at frame-one to 1.0 at whatever end-frame. But it can slope downward instead, causing things to run backwards. Or it can curve up-and-down for the [Purina Cat Chow commercial…] “Chow chow chow” effect…

I think the easiest way would be to make cube you want to end up with an emitter. Subdivide it a couple times, then make it the parent of the smaller cubes you want it to be made up of, then activate dupliverts. Scale the smaller cube so that it forms a perfect cube when the copies are duplicated on the emitter (probably best to work in grid units for easier presicion). Set up the particle emitter like you would for an explosion. Then, like the others have said, run a backwards time IPO to reverse the particle effect.

The way the time IPO works could be a tad confusing. Sorry, I;m no that great at explaining things so bear with me. The vertical axis counts the frames of the original animation. The horizontal axis counts the frames of the animation after the Time Ipo takes effect. In this case, find the frames where your explosion starts and ends. The end frame is where the time IPO should start on the vertical axis. The start frame is where it should end. The horizontal space between them is how long the time modified effect will take.

ack, I probably could have worded that better…oh well

about the time IPO, anyone else wish there was on option to toggle it on and off, so you could edit the original animation easily? You can kinda do that by copying the curve to the buffer, deleting, and re-pasting after you’re done, but a toggle feature would be nice