I’m starting this new year sharing with you a custom ICE node that was on my hard drive since last year… It generates the polygonal description to build a 3D Convex Hull.

You can download it here. It includes two scene files and the win64 dll.
The C++ sources are also there if you need to compile it for an other platform.

I used the Gift wrapping algorithm and  added a mode to generate NGones when several triangles are coplanars (just un-check “Triangulate Coplanar” to use it) but, be careful, this mode is buggy !

Olivier is one of those talented guy used to be the director, the 3d artist and the compositor of some motion design works since several years. The first time I met him (some… years ago now…) he was doing a fantastic job for some Eurosport billboards using Lightwave and After effect (I was also using LW at this time). We started to exchange ideas about ways to “make things” in 3D. I was not yet so dedictated to the technical side of 3D, and I really think that those discussions with Oliver pushed me in this direction. It was obvious that its artistic vision was way beyond my limited talents in this area, and it was obvious that I was enjoying giving him technical advices for his various projects.

But lets speak about his new film. This is a command from the “Club des directeurs artistiques”. It is a french club of artistic directors making an awards ceremony every years for the best commercials. He was in charge of the official film. He used Softimage for all the 3D and I think it is a very good illustration of what an artist can do with ICE. Olivier never learned programming languages and his education background is not really oriented on math but rather on art as he did the “Ecole nationale supérieure des beaux-arts” in France. He often try various ICE compounds found on the web and modify them using its own logic without writting a single line of code ! He told me that without an internet connexion, ICE would not be so useful to him . The nice thing about ICE is that it is really interactive. No need to always understand what you are doing, if the instantaneous feedback in the 3D viewport is looking nice .

Finally, here is the film. Pump up the volume and enjoy this one man work :

My first test was trying to slice an existing mesh using a radial design. It was not so bad but rather complex. I needed something more simple. We’ve got sphere or torus primitives, and I wanted a shattered glass primitive, nothing more.

Looking at the some pictures and videos of glass shattering I noticed that the  radial cracks and  rings starting at the center of the impact  could be simplified to an “un-wrapped cylindrical extrusion”. As I’ve got already an ICE compound to build such extrusion (and as I am lazy), I choosed this solution.

Re-factoring this compound, it was easy to generate the good polygonal description (the array describing the vertices of each polygons). Then the job was to set the position of this extrusion in a radial pattern with some randomness scaled by the distance from the center. The first tests were not so bad. Here is a little demo :

And here is the ICE compound . To use it, just create an empty polygon mesh, add an ICETree in the modeling region and connect the compound.

At least here is a little rendered animation using Momentum for the simulation (a Softimage open source plugin using the Bullet Physics library) and Arnold for the rendering (using the Softimage to Arnold plugin) :

Thats all for this first public ICE modeling compound ! If I find some time, maybe other ones will follow…

A Python viewer to scrub your icecache, Nice .

And feel free to contribute !

2010 was all Softimage for me too as I joined this incredible team in april .

I wish you all the very best for 2011 !

Guillaume Laforge

Enjoy !

(windows user can drag n drop the icon on an ICETree graph)

"__LowestPointIndexInIsland" per point attribute

Our goal now is to build a polygon island index attribute like this : Once again, we need to think in which context we can see our data. If we stay in the “per point context”, we will only see one point at a time. It would be harder to build an algorithm to get our polygon island index this way.
But if we could build just an array (in per object context) of all our “__LowestPointIndexInIsland” attribute it would be easier to deal with (we will see latter how).

“Build Array from Per Point Data” :

In Softimage 2011, you just need to use a “Build Array from Per Point Data” compound. But you can easily build a similar one in any versions (and it will be an other excuse to learn something new !).

Build array from per point data

First we create an array with the same size as the number of points in our object.
Then we build an other array from the first one using its sub indices. Here is an example :

• Index :  0 .  Array A data : a value  >  Array B data  is Index 0.
• Index :  1 .   Array A data : a value  >  Array B data is Index 1.
• …
• Index :  n.   Array A data : a value  >  Array B data is Index n.

If we feed an “ID to Location” node with this array, it will return an array of locations.

From this array, we can get all our “__LowestPointIndexInIsland” attributes in one go !

The “zipped” array :

Or how to create an array B [n, n+3, n+6] from an array A  [n, n, n,  n+3, n+3, n+3,  n+6, n+6, n+6].
We need to iterate through array A values and push the value to array B only if it doesn’t exist in Array B.
The way you iterate along an array in ICE is using a Repeat node with the number of repeats set to the array size. We will need to build a repeat counter attribute to be able to select the “current value” in our Array A  inside the repeat execution. As it is a common setup in ICE, I built my own compound some time ago to deal with this kind of executions.

zipped array graph

I usually name the iterator attribute “__ITERATOR_my_name”. This way it is easy to know from a get data that we are dealing with this kind of variable.  It is always nice to be able to figure out a graph without zooming on each nodes. From the “zipped array graph” with can easily read that we get four attributes from the object  istself (blue nodes) and that we set one attribute (the light blue one). In fact we also set the itterator attribute at each repeat execution but we already know that from its name. I’m hiding the iterator attributes from the explorer using “__” (as in ICE there is only one global name space).
Once you are comfortable with the Repeat node workflow, if your are using Softimage 2011, you can directly use the “Repeat with Counter” compound !

The index array :

Now from the array B [n, n+3, n+6] we can build an array C[n, n+1, n+2]. We will use again a Repeat node, an itterator and some Array nodes.

We are doing a very similar graph and finally get our Polygon Islands Index. If you haven’t download those compound from the first Polygon Islands post, here is the link again. Once the addon installed, you could dive inside the “Create Polygon Island Index” compound and figure out how it works.

Cheers !