Return-Path: Received: from mail-vc0-f173.google.com ([209.85.220.173] verified) by media-motion.tv (CommuniGate Pro SMTP 4.2.10) with ESMTP-TLS id 5183947 for AE-List@media-motion.tv; Wed, 21 Aug 2013 19:35:51 +0200 Received: by mail-vc0-f173.google.com with SMTP id id13so472828vcb.18 for ; Wed, 21 Aug 2013 10:48:01 -0700 (PDT) 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=QG0sZ/BsuXwsZfd/8axhdPjvcpJ7XnQ9kklRUbQOx6U=; b=I6h0YlOfpI9W9kMcPjgzsbMYf1Ur6NSgoAO9AhPr3VfULXFl8UU+vQ1HcPvmBSfGWb iu7B14zc4YbDvS+IbG7lL+XPUBRyP8zA9t898Xj4P6xzWzNfz/qM+yDR6p2hp9sE3UwH vakOWOdCrpQUet3KhddCkX8brMINBmCiMHl46S+ApYUdQKHFCAF0SsPGiS8wdsPVGWLH vBNaGg/wpfN1KYvGtF2ppQE84s5bYx3FPtbyRlaJLwVHcl4S7SimIZnUhbHLxP/UPREf yMXpMs3u9aDFsffyZX74IZAWueCovXjmGaZ8rCJmkNNL1JBNo4hIt1x/TFxE6fmTdxOK yUrw== MIME-Version: 1.0 X-Received: by 10.220.76.10 with SMTP id a10mr1522983vck.31.1377107281052; Wed, 21 Aug 2013 10:48:01 -0700 (PDT) Received: by 10.52.76.39 with HTTP; Wed, 21 Aug 2013 10:48:00 -0700 (PDT) In-Reply-To: References: Date: Wed, 21 Aug 2013 10:48:00 -0700 Message-ID: Subject: Re: [AE] Fading a light beyond a certain angle From: Darby Edelen To: After Effects Mail List Content-Type: multipart/alternative; boundary=001a11c20ac84e09f104e478c637 --001a11c20ac84e09f104e478c637 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable I'm not sure that I've understood the goal but here's an expression that will fade the light as it leaves a specified field of view: inner =3D 20; outer =3D 50; if(inner < outer){ c =3D thisComp.layer("Camera 1"); cv =3D [0,0,1]; p =3D normalize(c.fromWorld(toWorld([0,0,0]))); iBound =3D Math.cos(degreesToRadians(inner / 2)); oBound =3D Math.cos(degreesToRadians(outer / 2)); angle =3D dot(p,cv); linear(angle, iBound, oBound, 0, value); } else value; So in the above example the light would be at 'value' intensity when it's within a 20=B0 range of the view center and 0% intensity when it's outside = of 50=B0 from view center. If you want the light to turn off quickly choose an inner value that is close to the outer value. If you want it to fade gradually choose values that are farther apart. I've only included rudimentary error prevention so if inner and outer are the same value or inner is larger than outer the expression will default to the light's keyframed intensity. On Tue, Aug 20, 2013 at 5:58 PM, Alex Czetwertynski wrote: > Hello > > I'm trying to figure out an expression to control the brightness of a > rotating light. > My light is turning on itself, on the Y axis. Everytime it passes 90 > degrees, rotating away from the camera, I'd like to reduce its intensity, > and then bring it back when it is starting to enter the quadrant in which > it will face the camera. > > If the camera was just rotating once, I'd use a linear expression that > mapped 180 to 270 degrees and faded the light in between those two values= , > but it is constantly looping=85 > I thought I might be able to use Radians, but they, obviously, keep > increasing with the degrees=85 > > Any suggestions? > > Thanks! > Alex > > > +---End of message---+ > To unsubscribe send any message to > --001a11c20ac84e09f104e478c637 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable

I'm not sure that I've understood the goal bu= t here's an expression that will fade the light as it leaves a specifie= d field of view:

inner =3D 20;
outer =3D 50;
if(inner < out= er){
=A0=A0=A0 c =3D thisComp.layer("Camera 1");
=A0=A0=A0 cv =3D [= 0,0,1];
=A0=A0=A0 p =3D normalize(c.fromWorld(toWorld([0,0,0])));
=A0= =A0=A0 iBound =3D Math.cos(degreesToRadians(inner / 2));
=A0=A0=A0 oBoun= d =3D Math.cos(degreesToRadians(outer / 2));
=A0=A0=A0 angle =3D dot(p,cv);
=A0=A0=A0 linear(angle, iBound, oBound, 0= , value);
}
else value;

So in the above example the ligh= t would be at 'value' intensity when it's within a 20=B0 range = of the view center and 0% intensity when it's outside of 50=B0 from vie= w center. If you want the light to turn off quickly choose an inner value t= hat is=20 close to the outer value.=A0 If you want it to fade gradually choose=20 values that are farther apart.

I've only included rudimentary er= ror prevention so if inner and outer are the same value or inner is larger = than outer the expression will default to the light's keyframed intensi= ty.

On Tue,= Aug 20, 2013 at 5:58 PM, Alex Czetwertynski <alex@disciplefilms.com= > wrote:

Hello

I'm trying to figure out an expression to control the brightness of a r= otating light.
My light is turning on itself, on the Y axis. =A0Everytime it passes 90 deg= rees, rotating away from the camera, I'd like to reduce its intensity, = and then bring it back when it is starting to enter the quadrant in which i= t will face the camera.

If the camera was just rotating once, I'd use a linear expression that = mapped 180 to 270 degrees and faded the light in between those two values, = but it is constantly looping=85
I thought I might be able to use Radians, but they, obviously, keep increas= ing with the degrees=85

Any suggestions?

Thanks!
Alex

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