Return-Path: Received: from mail-we0-f181.google.com ([74.125.82.181] verified) by media-motion.tv (CommuniGate Pro SMTP 4.2.10) with ESMTP-TLS id 5284938 for AE-List@media-motion.tv; Wed, 13 Nov 2013 20:02:56 +0100 Received: by mail-we0-f181.google.com with SMTP id w61so847322wes.26 for ; Wed, 13 Nov 2013 11:04:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=bZdln2zxZiEfyjeDkKV94PHUZS60VsRxN7/T/vd2afc=; b=DBlfQSJURRlWClXkQ2xFAtYMYjqgI0ScR49yLoecnBaoFSEKVB3L+M7U5iDPD9jGLS jhrRdqLifciIiw8eDXlEojU0w/g1nPk4IU0yRKeDSiebw7u39bhmwjfvGl+SVHg0A/es QW6k9C9JsrE7sZw3sbyKsEJQwe+oGXYNvcSNWHZaRZay1oMw8CiHWGiO+N+Tiejku+xw Ee1JVA3ed3osEnWKxT5DnMkGj73WhE17Z9je0i7v1Spni7YACJaRd2DpzXJZHac8Gt5B fJErWRYTsCB6sJQcFsIJezM+pDJBEGuaTmmKYz2s8ReOsajiE8XN7QW3tjeNTB8dhGKh j67Q== MIME-Version: 1.0 X-Received: by 10.180.189.68 with SMTP id gg4mr15451547wic.46.1384369484705; Wed, 13 Nov 2013 11:04:44 -0800 (PST) Received: by 10.194.71.163 with HTTP; Wed, 13 Nov 2013 11:04:44 -0800 (PST) In-Reply-To: References: Date: Wed, 13 Nov 2013 14:04:44 -0500 Message-ID: Subject: Re: [AE] freeze frame from precomp - expression needed to not get duplicates From: rendernyc To: After Effects Mail List Content-Type: multipart/alternative; boundary=001a11c353005fb7e404eb13a333 --001a11c353005fb7e404eb13a333 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable which is why using index numbers on consecutive layers to map to the time of the layers in the precomp is a good way to go. each index will give you a unique image On Wed, Nov 13, 2013 at 1:57 PM, Byron Nash wrote: > I've written something like this in script form(Fisher-Yates) although I > did not know it had a name. I can't think of a good way to do it with > expressions without killing the render. It would need to go through many > iterations for each layer on each frame to get it going. I imagine with 1= 25 > layers you would start to get speed issues. > > > On Wed, Nov 13, 2013 at 6:35 AM, Chris Zwar wrote: > >> Grrr sorry, I decided to google my own suggestion and discovered I was >> wrong. What you need is a Fisher-Yates algorithm: >> >> http://en.wikipedia.org/wiki/Fisher=96Yates_shuffle >> >> Luckily there's plenty of examples on the web, and it seems that writing >> a script to shuffle cards is a common task given to computer students, s= o >> if you think of your 300+ faces as a deck of 300 cards then you should b= e >> able to google a solution sooner or later. >> >> >> -Chris >> >> >> On 13/11/2013, at 10:23 PM, Chris Zwar wrote: >> >> This question has come up before, and I remember someone else explaining >> that you will need to use a custom random number generator, and not just >> the generic random expression. As you have realised, the problem with >> random() is that even though the numbers are random there is nothing to >> stop the same number being randomly chosen more than once. >> >> You need to use a "monte carlo" random number expression, which I don't >> have and am not sure where you find one. I think the algorithm is norma= lly >> used to shuffle a deck of cards, hence the name. I guess when you want = a >> computer to create a random deck of cards it's important to know that ea= ch >> card only appears once! >> >> It might be quicker to do it manually. >> >> HTH >> -Chris >> >> On 13/11/2013, at 9:18 AM, Greg Balint wrote: >> >> Got a quick one here.. something i'm probably just either not familiar >> with, or I'm thinking too hard about it. >> >> I've got a large grid wall of squares with people's faces in them. Each >> face panel is the same precomp with this expression in the time-remap >> attribute. >> >> seedRandom(index,true); >> myFrame =3D Math.floor(random(303)); >> framesToTime(myFrame) >> >> Basically this grabs a random frame from the precomp, which is about 10 >> seconds long, and shows it as a freeze frame for that particular layer. >> >> I've got 125 face panels all using this expression, and for the most par= t >> it works wonderfully.. they all have random faces on them, and if I add >> another layer, the random seed changes and I get a whole new slew of fac= es >> (which doesn't matter in this instance, but i could see that as a proble= m >> in others) >> >> My issue is, even though I've got over 300 frames (each frame with a new >> face) in my precomp.. the randomness is grabbing duplicates.. in some ca= ses >> 2-3 pairs of duplicates over the course of the 125 it chooses. >> >> >> Anyone know of a way to append this script so that it does not choose >> something it has already? >> >> I'd even be fine if there were a way to use an expression to grab frames >> sequentially from the precomp and then I could just hand choose to make >> sure there's no duplicates in the first 125 frames. >> >> I think i might just be overthinking this, but I'm not sure if I've seen >> a "check for duplicate and don't use" sort of expression before. >> >> thanks in advance. >> >> -- >> >> ///Greg Balint >> //Art Director / Motion Graphics Designer >> /321.514.4839delRAZOR.com/ >> >> >> >> > --=20 danny princz vimeo.com/rendernyc --001a11c353005fb7e404eb13a333 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable
which is why using index numbers on consecutive layers to = map to the time of the layers in the precomp is a good way to go. each inde= x will give you a unique image


On Wed, Nov 13, 2013 at 1:57 PM, Byron Nash <byronnash@gmail.com&g= t; wrote:
I've written something like this in script form(Fisher= -Yates) although I did not know it had a name. I can't think of a good = way to do it with expressions without killing the render. It would need to = go through many iterations for each layer on each frame to get it going. I = imagine with 125 layers you would start to get speed issues.


On Wed, Nov 1= 3, 2013 at 6:35 AM, Chris Zwar <chris@chriszwar.com> wrote= :
Grrr sorry, I decided to google my own = suggestion and discovered I was wrong. =A0What you need is a Fisher-Yates a= lgorithm:


Luckily there's plenty of examples on the web, and = it seems that writing a script to shuffle cards is a common task given to c= omputer students, so if you think of your 300+ faces as a deck of 300 cards= then you should be able to google a solution sooner or later.


<= div>-Chris

On 13/11/2013, at 10:23 PM, Chris Zwar <chris@chriszwar.com&g= t; wrote:

This ques= tion has come up before, and I remember someone else explaining that you wi= ll need to use a custom random number generator, and not just the generic r= andom expression. =A0As you have realised, the problem with random() is tha= t even though the numbers are random there is nothing to stop the same numb= er being randomly chosen more than once.

You need to use a "monte carlo" random number expr= ession, which I don't have and am not sure where you find one. =A0I thi= nk the algorithm is normally used to shuffle a deck of cards, hence the nam= e. =A0I guess when you want a computer to create a random deck of cards it&= #39;s important to know that each card only appears once!

It might be quicker to do it manually.

HTH
-Chris

On 13/11/2013, at 9:18 AM, = Greg Balint <delrazoraelist@gmail.com> wrote:

Got a quick one here.. somet= hing i'm probably just either not familiar with, or I'm thinking to= o hard about it.

I've got a large grid wall of squar= es with people's faces in them. =A0Each face panel is the same precomp = with this expression in the time-remap attribute.

seedRandom(index,true);
myFrame =3D Math= .floor(random(303));
framesToTime(myFrame)

Basically this grabs a random frame from the precomp, which is about 10 = seconds long, and shows it as a freeze frame for that particular layer.

I've got 125 face panels all using this expression,= and for the most part it works wonderfully.. they all have random faces on= them, and if I add another layer, the random seed changes and I get a whol= e new slew of faces (which doesn't matter in this instance, but i could= see that as a problem in others)

My issue is, even though I've got over 300 frames (= each frame with a new face) in my precomp.. the randomness is grabbing dupl= icates.. in some cases 2-3 pairs of duplicates over the course of the 125 i= t chooses.


Anyone know of a way to append this scri= pt so that it does not choose something it has already?

I'd even be fine if there were a way to use an expression to grab= frames sequentially from the precomp and then I could just hand choose to = make sure there's no duplicates in the first 125 frames.

I think i might just be overthinking this, but I'm = not sure if I've seen a "check for duplicate and don't use&quo= t; sort of expression before.

thanks in advance.

-- 
///Greg Balint
//Art Director / Motion Graphics Designer
/321.=
514.4839
delRAZOR.com/






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