Per-light exporting example

[pbowmar]

Here's an example of per-light exporting using the cool new feature in H9's Mantra. This was started by Jerry on the mailing list.

Basically, you export each thing you want per-light inside the Illum loop, then in the Mantra ROP, you specify the same VEX export variable multiple times, but point to a different light for each variable.

I added a couple of very simple custom expressions to make life easier when setting up the ROP that extract the light and the variable for you from the Deep Raster entry (uses $CH in the custom expression which returns the name of the channel it's being used in).

The ROP is something that you'd ultimately write a simple RMB script for, that would automagically scan for all export variables and all lights and fill the ROP in for you.

Also, sadly VOPs still is not complete, there are quite a few VEX functions that do not have VOPs I have an embedded VOP that exposes the BRDF functions, which are some of the VEX functions without VOP equivalents. You could do this with an inline VOP, but I find those fragile and ultimately to be avoided if at all possible.

Cheers,

Peter B

 PerlightIllumLoop_v0001.hip.gz (33.99K)
Number of downloads: 311

[old school]

Thank-you Peter!

The two convenience functions outlight() and outvar() are nice, simple and work well. Should be default functions IMHO.

I usually channel reference the Quantize and Pixel filter to the beauty default pass or to the first light layer if you only want an 8bit beauty C pass. That way when you compare the beauty C with the slap comp of all the lights they are the same. Just do a diff to check. Could even automate this before you pass the plates on to the compositors to make sure all the lights made it.

Quote

Also, sadly VOPs still is not complete, there are quite a few VEX functions that do not have VOPs sad.gif I have an embedded VOP that exposes the BRDF functions, which are some of the VEX functions without VOP equivalents.

Keith is cleaning up a four part OldSchool blog on how to take a default vex function and build a "sesi approved" VOP complete with signatures complete with videos and support files.
I figure we can all (sesi user community) contribute to this project. Transpose VOP is done.

[j35ta]

Thanks you very much Peter.

I have it set up and working well. I was wondering if anyone knows if it is possible to implement bump mapping with this.
I did try but it stopped working so I'm guessing the VEX code needs to change to accommodate this, or I'm going about it
the wrong way.

Thanks

Jerry

[pbowmar]

Hi Jerry,

I have something a little better coming soon with more automation but I'm running into bugs/issues in 9.1.xxx that's slowing it down.

What do you mean by bump mapping? That shouldn't be affected by the per-light stuff since it's just a manipulation of the normal. I'm not clear what the issue is.

Cheers,

Peter B

j35ta, on May 27 2008, 07:31 AM, said:

Thanks you very much Peter.

I have it set up and working well. I was wondering if anyone knows if it is possible to implement bump mapping with this.
I did try but it stopped working so I'm guessing the VEX code needs to change to accommodate this, or I'm going about it
the wrong way.

Thanks

Jerry

[zasid]

Hello Peter,

I am new user to Houdini,can you please explain it a bit where it can be useful?I mean to ask some practical example of how it can be used in wat scenarios? I will be thankful.


zasid

[pbowmar]

Hi Zasid,

Basically, in a lot of professional environments you want to be able to make the large majority of your look decisions in a compositing package instead of re-rendering 3D elements, since it's much faster to work in 2D than 3D. So, by splitting out everything from the render into their own layers/channels/passes (everyone seems to use slightly different terminology) you can rebuild the image in the composite package, and then make colour, brightness and other changes in close to real time.

Cheers,

Peter B

zasid, on May 27 2008, 04:01 PM, said:

Hello Peter,

I am new user to Houdini,can you please explain it a bit where it can be useful?I mean to ask some practical example of how it can be used in wat scenarios? I will be thankful.
zasid

[zasid]

Thanks Peter.

[Aearon]

how would this work for instanced lights?

how would you..

A ) get the sum of all instances of one light combined in one pass
B ) get a pass for each instance of the light

This post has been edited by Aearon: 28 June 2008 - 11:27 PM

[pbowmar]

Aearon, on Jun 29 2008, 12:25 AM, said:

how would this work for instanced lights?

how would you..

A ) get the sum of all instances of one light combined in one pass
B ) get a pass for each instance of the light

Hmm, for #1 I'm going to say that you'll need to use getlightname() somehow, but I'd have to have a play. Might be tricky since instanced lights get named automatically.

Getting a pass for each instance wouldn't be too hard since each instance passes through the illuminance loop. The only tricky bit would be configuring your deep raster outputs on the Mantra ROP which would have to be done with a script of some kind that "knew" about the instanced lights.

Cheers,

Peter B

[kensonuken]

hey peter im looking for the ROP I know the general way how its done using rsl but i would like to know how it can be done using mantra. Ive tried using mantra node but couldnt understand how to get the renders into different image files.. can you tell me how pls..

[pbowmar]

Sorry, I don't understand. The example .hip file has the ROP configured already, unless I've forgotten totally what I did in there

Cheers,

Peter B

[kensonuken]

i mean when i render image I coudnt find where these images are being stored...