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David Gary

Silly Challenge

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So... You asked for challenges... :lol:

For procedural minds ,

If and only if you have time!

1)Break a piece of geometry in shards ( each shard is not a single primitive but a group of primitives , which is much mooore difficult to achieve)

2)Animate the shards with a particle network ( so it's not just instancing...).

sorry i didn't post a more complex animation, but ut's just to show the concept

3)Plus ( that's what i did) : the division of the piece must be procedural ( to have control over crack patterns, that is you must define procedurally the groups of primitives).

EVERYTHING MUST BE PROCEDURAL :)

fracture.gif

sorry for the adGif logo. I do not create animated GIFs very often!

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Okay Mr FrenchOP, Please disclose brain power. The ice breaking tutorial is easy enough but for the life of me I can't figure out how to group the primitives, but then I'm fairly new to Houdini. I'm sure I'll kick myself when I find out.

Thanks

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I'd appreciate a hint concerning the following: can a single group SOP output multiple groups or a fuse SOP do multiple seperate fusions ?!

Defining the pattern for the actual groups seems easy enough for me, and I think I know how I could create a script that simply creates a seperate fuse or group SOP for each fragment, but having all these seperate fuse / group OP's doesn't sound like an elegant solution to me / has little procedural beauty ;).

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:wacko: I should have studied the online help more carefully, thanks

Anyhow, it's now working more or less. Once I'm more happy with the pattern I'll post my solution.

Jens

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Yo guys! Did any of you crack this challenge? I am working on my master's project at the moment - basing much of my particle stuff on the ice breaker (with basher object) - and I would really like to be able to group the primitives into different sized chunks.

Question: wouldn't it be possible to create a lumamap in COPs (some kind of shattermap) and using the pic()-function, grouping and fusing primitives based on this information?

ANY input on this is extremely welcome!

:D

Cheers, jostein.

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I tried working on this last night for about 4 hours and didn't get anywhere. <_< I tried using the facet to make everything unique and then group primitives to form the shapes I want. Problem is I could figure out how to fuse the primitives together to be one big chunck instead of 5 individual ones. But this gives you no easy way to control the crack patterns anyways so back to the drawing board. :o

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Hey, guys! Did anybody solve this challenge - it remains a big mystery to me, no matter how hard i tried :( FrenchOP, please, show us your magic!!!

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I wasn't really happy with my solution and I'm going to do a hopefully nice/cleaner setup, but anyhow ...:

I created an extra attribute on the points of the grid and using a VEX SOP I simply applied a slightly modified voronoi kinda noise on this attribute: the voronoi noise has a bit of this cobblestone look. So far so good... now I used the Partition SOP to create the unique groups based on this . I don't know anymore if I created primitive or point groups, but I used something similar to the following roule: "point ("/obj/Ice/IceBr", $PT, "myCustomAttribute", 0)"

Using the trick Sebarrik suggest in his "prim sort otl" I did a loop, through all the groups and animated these that way. Unfortunally my noise would generate numbers ranging from as low as 00001 up to 99999 (--> ugly group names) no matter if I'd have only 7 groups created via the partition using these values or 1000.

Looping though all those non-existant groups was very inefficient and therefore I created an intermediate attribute and tried several simple hash functions to create somewhat unique numbers ranging only from 0 - 4 * times the number of unique groups the partition SOP would create. Trouble is, for proper hashing you usually need some collision resolving and I don't know how to do so using the expression language in Houdini. Anyhow anyone who's intrested in the hashing theory can get a good introduction on this subject in the good old "Introduction To Algorithms" by Cormen.

In the end using this "hashed" groups some of the initial groups got fused and therefore a fair bit of trial and error was required when playing with the hasing functions.

Well, I guess FrenchOP has a nicer solution for this ;) If I find my old scene file I'll post it.

Jens

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late reply, but here is a hint.... check the apprentice CD for a hip file named explode.hip... think thats the name of it.

look and ye shall recieve...

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I'M BACK I'M BACK I'M BACK I'M BACK I'M BACK I'M BACK

Hi Guys!

I had no Internet connection since June 2004 !!!! ( long holiday at remote places with no Internet ( or just mail ) and many problems to get my connection back with f..ing french providers - Not working in an office.. )

Now, I have it back!

I'm gonna explain everything. And more!

( I will do a Three-Parts Video Tutorial with general concepts for doing this kind of FX and some others like

- creating a fluid flow through a L-system ( for lava flow - blood flow)

- "peeling" a surface with arbitrary peels ( often needs math).

Just give me time! ( and luck with Internet! )

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Hi guys!

I spent my Sunday afternoon struggling with my computer to do a correct ( and even good sometimes) video tutorial for the Breaking Objects effect ( no error allowed while recording myself in realtime).

Sorry for my -sometimes- ugly akzent.

The other tutorials are coming soon ( the Avalon Fx is almost done)

The main concept of this three or four-part tutorial is copying operations, that is instancing an operation ( or several ) applied to pre-defined parts of an object.

Click here to watch the tut! ( sorry it weigh so much! )

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Beutifully done, FrenchOp!!!  Very elegant!

15218[/snapback]

I agree - very nicely done.

A lot of advanced Houdini ideas in there, very well put together.

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That is a fantastic tute. I like the line on your page

"Excuse-me if my English is sometimes uncorrect."

You should have sead "incorrect" but it adds a beautiful single sentence of self contained irony. Please don

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