Challenge: Make the fastest island selection compound

[iamVFX]

I really like Oleg's compound. Result of it in a per point context and its fast

[Chris_TC]

I really like Oleg's compound. Result of it in a per point context and its fast

Where can this compound be found? The speed looks great, I'd love to try it out.

[iamVFX]

Where can this compound be found? The speed looks great, I'd love to try it out.

Here, the fifth post, but you have already tested it, didn't you?

[Chris_TC]

Oh sorry, yes of course I have. I thought this was a different one.

[rray]

some compounds here I made recently, work reasonably fast, based of Guillaume's method, but simplified
#1: "Initialize Island Lookups"
#2: "Get Island Locations": per point, fetches array of locations of all island points for subsequent attribute lookups, requires Compound 1 executed

Don't know how much this is already covered in this thread, just needed some quick search&paste place to post this in

[julian johnson]

I never seemed to have any problems with Oleg's compound so I'm not sure this variant will work on other machines but in the attached scene I've used the same basic technique as Oleg (i.e. growing outwards from the initial vertices attached to the target poly) but tried to filter the search vertices so that you're not iterating over the same points. I set up a variant of the test scene with highly subdivided topology and my tree executes in about 1.75s and Oleg's in about 7.5s (on my machine).

http://www.exch.demon.co.uk/xsi/files/i ... nge_JJ.rar

Let me know if this a) works and b) if my timings are grossly wrong! On the surface it seems to do the job. The scene is 2013 SP1.

[julian johnson]

For completeness, just updated the scene to include a comparison of the two basic techniques a) iterating outwards as Oleg does and b) identifying all the polygon islands first and then deriving the island-to-be-actioned from the polygon index (similar to Reinhard's compounds above). The former is always about 30% quicker but the latter does give you the polygon island indices as a bonus.

http://www.exch.demon.co.uk/xsi/files/i ... island.rar