Glass Shatter - Glue Problem

[Marink]

Hi,

I'm just attempting to create a radial shattering of a glass, such as a bullet going through a window, however I manage to get the 'bullet' through okay but after a slight while the rest of the window begins to fall.

I've used RBD Glue to keep all the pieces together, key'ing the glue off at the moment of impact and then turning it back on again, however the glass still continues to fall. I don't know whether I should try turning the impulse down or whether it's something else I should try.

Does anyone have any ideas?

Thanks,

Gary

radial_Implementation.hipnc

Edited March 6, 2012 by Marink

[Darric]

You can't "reglue" objects by increasing their glue strength (even to -1); once the glue breaks, the strength value is ignored. In your scene, your animated glue strength is breaking the glue of all your pieces once it hits zero, and once your pieces are all unglued, the strength value is no longer relevant.

What you can do is re-initiate their glue using the "Glue to Object" field on the rbdstate node (remember, all the pieces of RBD Glue setup are glued to an empty object that takes the name of the node, in this case "box", so merely switching between "" and "box" in that field will do the trick). The next problem is you need a way to separate out the pieces you want to reglue from those you don't, otherwise the entirety of the shattered glass will behave as a single piece again. There a few ways to do this, for artistic control it probably makes more sense to isolate the pieces you want in SOPs, and either use two RBD Glue objects in the Dopnet, or use an attribute to control this.

For the purposes of demonstration though, you can cheat what you're going for by using an expression to reglue the pieces that don't move much in X, leaving the pieces that do move far enough away from the middle to keep moving freely. I've attached a modified scene that does this. All the changes are on the new RBD State node. Note that I'm not animating the strength at all, only the "Glue to Object" field.

Other notes: You can't glue to static objects, so right now your Glue to the "floor" object doesn't do anything. I also reduced your collision substeps drastically on the RBD Solver node merely for testing, but really you can probably get away with much less than the default settings for an effect like this, in order to drastically reduce sim times.

Hope that helps!

radial_implementation_darric.hipnc

Edited March 7, 2012 by Darric

[Marink]

You can't "reglue" objects by increasing their glue strength (even to -1); once the glue breaks, the strength value is ignored. In your scene, your animated glue strength is breaking the glue of all your pieces once it hits zero, and once your pieces are all unglued, the strength value is no longer relevant.

What you can do is re-initiate their glue using the "Glue to Object" field on the rbdstate node (remember, all the pieces of RBD Glue setup are glued to an empty object that takes the name of the node, in this case "box", so merely switching between "" and "box" in that field will do the trick). The next problem is you need a way to separate out the pieces you want to reglue from those you don't, otherwise the entirety of the shattered glass will behave as a single piece again. There a few ways to do this, for artistic control it probably makes more sense to isolate the pieces you want in SOPs, and either use two RBD Glue objects in the Dopnet, or use an attribute to control this.

For the purposes of demonstration though, you can cheat what you're going for by using an expression to reglue the pieces that don't move much in X, leaving the pieces that do move far enough away from the middle to keep moving freely. I've attached a modified scene that does this. All the changes are on the new RBD State node. Note that I'm not animating the strength at all, only the "Glue to Object" field.

Other notes: You can't glue to static objects, so right now your Glue to the "floor" object doesn't do anything. I also reduced your collision substeps drastically on the RBD Solver node merely for testing, but really you can probably get away with much less than the default settings for an effect like this, in order to drastically reduce sim times.

Hope that helps!

That really helped thanks, I didn't know that you couldn't re-glue objects back together after they'd been split which is probably why I was having so much trouble keeping it up. At the moment around from 60-70 gravity takes over and the mirror still begins to fall, is this something I can change, would I need to set the gravity for example to only affect certain groups?

On the subject of groups, how would I go about setting the Glue to Object, would I just have to input "box" for example, as I've tried setting groups, but the glass seems to immediately break up?

Thanks for your help by the way, I really appreciate it.

Gary