[Sidefx-houdini-list] vops and point clouds

Olex P hoknamahn at gmail.com
Thu Aug 20 07:33:10 EDT 2009


Hi Nicholas,

I believe all what you need is just go through all the points in radius and
sum all the values of alpha on them. The order doesn't really matter.

On Thu, Aug 20, 2009 at 11:54 AM, Nicholas Pliatsikas <nick_p102 at hotmail.com
> wrote:

>
> Didnt realise the refract limits would affect the point cloud data. I will
> check into that.
>
> I had a good think about what was causing the problems last night, I think
> its due to how a random ID variable is working in relation to the order in
> which the point cloud data is being seached.
>
> For example if the current points random ID value is bigger then the random
> ID value of the next point it will be ignored, that point will be ignored. I
> guess what is really needed is some way of sorting the point datas random ID
> values then bring those in sequential. But I have a feeling thats not
> possible at all. So im trying another approach, and changing the order of
> where the random call is happening, i.e clipping it with the alpha map then
> running the if statement to check what the highest visible layer is.
>
> This is much tricker then i first thought..
>
> Cheers
> Nick
>
> > Date: Wed, 19 Aug 2009 09:40:51 -0700
> > From: daveinengland at gmail.com
> > To: sidefx-houdini-list at sidefx.com
> > Subject: Re: [Sidefx-houdini-list] vops and point clouds
> >
> > I can't get to the files you referenced because of our firewall, but have
> > you checked the refract limit on your objects? If this is too low, the
> rays
> > will be limited by this. Also, there is the opacity limit in the ROP may
> be
> > limiting your rays.
> >
> > Just a thought.
> >
> > Dave
> >
> > On Wed, Aug 19, 2009 at 2:25 AM, Nicholas Pliatsikas
> > <nick_p102 at hotmail.com>wrote:
> >
> > >
> > > Hey guys and gals.
> > >
> > > After doing a good bit of work on the point cloud shader ive hit a
> problem.
> > > To me it seems that there is some optimisations happening with the
> point
> > > cloud data or its just a bug with code/mantra .
> > >
> > > Basically when layering the point cloud circles it looks as if mantra
> is
> > > cutting out much of the underlying circles, creating a problem when
> layering
> > > images using alphas. i.e parts of the underlying images are cut off.
> > >
> > > I can't see a problem with the code i added, so I went back to the
> example
> > > Olex sent me and changed it to be additive. This illustrated the same
> issue.
> > > You can see a screen grab here
> > >
> > > https://rcpt.yousendit.com/727895459/45f82a647fbe6eae52df9dc836f604f3
> > >
> > > If it is a bug/limit with mantra I wills end this off to sidefx
> support.
> > >
> > > I have also saved out the additive version of the hipfile, you can
> download
> > > it here.
> > >
> > > https://rcpt.yousendit.com/727894133/de680b2c71c2c8d61f6dc0700d9d57a4
> > >
> > > I hope this is something we can get around as it will be a really nice
> way
> > > to add controlled details to scene. Just a note it also seems as if
> there is
> > > the odd point radius that isnt being added correctly either (the green
> > > circles at the bottom right of the screen for example)
> > >
> > > Cheers
> > > Nick
> > >
> > > > From: nick_p102 at hotmail.com
> > > > To: sidefx-houdini-list at sidefx.com
> > > > Date: Fri, 14 Aug 2009 15:55:02 +0000
> > > > Subject: Re: [Sidefx-houdini-list] vops and point clouds
> > > >
> > > >
> > > > Thanks for that Olex :) thats a great example, I see what you where
> > > meaning in your code about using the maxheight random calls. Just
> trying
> > > this out in vops, having some oddities but will try a few more times
> until i
> > > resort to vex coding ;¬) as i need to quite abit inside that loop.
> > > >
> > > > Cheers mucho!!!
> > > > Nick
> > > >
> > > >
> > > >
> > > > > Date: Fri, 14 Aug 2009 13:46:49 +0100
> > > > > From: hoknamahn at gmail.com
> > > > > To: sidefx-houdini-list at sidefx.com
> > > > > Subject: Re: [Sidefx-houdini-list] vops and point clouds
> > > > >
> > > > > Oops, that was toooo quick test. There is correct one
> > > > >
> > > > >
> > >
> http://www.hotmail.ru/download.php/?file=:pcdvd2.hip&host=alex-hawk.hotmail.ru/flashcard&user=alex-hawk&lng=ru
> > > > >
> > > > > On Fri, Aug 14, 2009 at 1:33 PM, Olex P <hoknamahn at gmail.com>
> wrote:
> > > > >
> > > > > > Hey,
> > > > > >
> > > > > > There is a quick example
> > > > > >
> > > > > >
> > > > > >
> > >
> http://www.hotmail.ru/download.php/?file=:pcdvd.hip&host=alex-hawk.hotmail.ru/flashcard&user=alex-hawk&lng=ru
> > > > > >
> > > > > > AA isn't included! :p
> > > > > >
> > > > > >
> > > > > > On Fri, Aug 14, 2009 at 12:24 PM, <eetu at iki.fi> wrote:
> > > > > >
> > > > > >> >> >> Hey Peoples
> > > > > >> >> >>
> > > > > >> >> >> Im currently working on an image bombing point cloud
> shader
> > > and hit
> > > > > >> a
> > > > > >> >> >> problem i dont quite understand how to solve.
> > > > > >>
> > > > > >> Here's a thread from Georg which might well be relevant for you
> > > > > >>
> > > > > >>
> > > > > >>
> > >
> http://forums.odforce.net/index.php?/topic/6967-a-shader-each-day/page__view__findpost__p__47148
> > > > > >>
> > > > > >> I vaguely remember another forum thread with someone battling
> with
> > > the
> > > > > >> same problem, but can't find it now for the life of me. I think
> it
> > > was
> > > > > >> about overlapping fakeshadow blobs, if you happen to be able to
> find
> > > it :)
> > > > > >>
> > > > > >> eetu.
> > > > > >>
> > > > > >>
> > > > > >> _______________________________________________
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> > > > > >
> > > > > >
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