Hi guys,

I'm currently trying to get my head around houdini so I stared a “window breaking” project. Here is my setup:

I'm fracturing my imported geo using some methods from a free hip file I found via google to get a spiderweb look. After fracturing the geo I'm writing it into a dopimport node.
I then created a autodopnetwork including my fractured object (the whole node where the fracturing is happening), the ball which acts as a bullet, a groundplane and a glue constraint to keep the pieces itself together.

So far so good, my problem is:

How can i “pin down” the outer fractured pieces to not be affected a) by gravity and b) by the bullet (until a certain amount of strength). Right now, the whole geo is falling down…

I guess i have to use groups to tell houdinin which objects should be affected by gravity and which not. Right? In my voronoi fracturing node i can select the desired polygons but after choosing “group dynamic objects” nothing happens.

In short: i got two geos, window and frame. They get merged and fractured in a certain way and written in an dopimport. The simualtion is a standard autodopnetwork. I want the frame and the glass pieces connected to the frame stay in place and not beeing affected by gravity until the pieces get pushed away by the sphere.

I hope its understandable and maybe some of you guys can help me out.

If it would help, i could upload some screens of my setup as soon as I'm back at my workstation.

I'm very new to the houdini apprentice version and this is the first “real life” project i try to finish… so a simple explanation would be much appreciated.

cheers

If you have everything glued together right then the pieces should remain in the window frame as expected.

This tutorial was very helpful for me: http://www.digitaltutors.com/tutorial/1091-Controlling-Your-Fractures-in-Houdini [digitaltutors.com]

Although you need to understand that the tutorial was done before ‘Packed Primitives" were available, so if you do follow it step-by-step, don’t use Packed Prims or parts of it won't work as expected.

First of all: thank you both for your reply.

Thanks for the sample file, i just had a look. How would you achieve the grid not to fall down at the beginning of the simulation? And how can you fix the outer polygons so the whol thing doesn't get pushed back?

I started with the bullet hit pattern file provided in this thread:

https://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&p=101577 [sidefx.com]

I then imported my geo and altered the fracturing to my needs. All i need to do now is pin down the outter polygons and make the whol thing stable a few meters above the ground. Only the broken pieces should be affected by gravity.

Since it's just a learning project I'm gonna upload the file, maybe someone could explain the errors i made and the missing things to achieve the desired effect.


@reelinspirations

Thanks for the link, since i still a pluralsight membership I'm gonna give it a try and maybe build the project from scratch with the shown techniques.

Check out this video, it explains how to install an anchor into the system to keep things from falling over.
https://www.youtube.com/watch?v=pwlCfLruRI4 [youtube.com]