Uberlight Super Sale

[Wolfwood]

That's right folks this week only. You can download Larry Gritz's amazing Uberlight for Houdini!. You heard me right, the Uberlight has been ported to VEX. You too can have this amazing light shader for the incredible low price of...NOTHING. And if you act now you can download the amazing UberLight Object. This handy little Object provides a visual tool for the Uberlight. Just look below!

Ok, seriously though.... since I moved recently I don't have access to prman anymore Unless I want to telnet . So I started porting over some of my favorite shaders to VEX. Since I use the Uberlight the most that got my attention first.

In the attached zip is.

vex_uberlight.vfl -

Ported from Uberlight.sl with some minor changes, like I removed the shadow stuff since that's what shadow shaders are for, although I did leave the blocker in because, blockers rock. (The dialogue script and .vex file are there too).

uber.cmd -

this is my contribution to the uberlight. It is a SOP network inside your Light Object that creates a light shape based on the parameters of the Uberlight. Some of the parameters it takes into account are,

lighttype

lightcolor

intensity

width

height

roundness

wedge

hedge

falloff

falloffdistance

UI Scale (this doesn't have an effect on rendering it is there so you can scale the SOP object from within SHOPs. I like to work with a SHOP parameter pane open somewhere so it allows me to keep all my controls together.)

Just install the shader and source the script ["source uber.cmd"]

You can source it as many times as you want, its even smart enough to make new objects and handle the names right. The Light Object's Sops are referenced by the Light OP's name. So the Light OP and the Uberlight SHOP should have the same name. The script takes care of all the creation stuff and channel referencing. (I hope).

The visual tool's color is based on Uberlight's parameters and while not an "exact" match to your final render it should be semi close.

Umm there is probably a half dozen things I'm forgetting to mention but I want to post this now. =)

I'll put this on my webpage along with some help files later tonight.

jim. :

Uber.zip

[stevenong]

Hey Jim,

This looks really cool!

Thanks for porting it over to VEX!!!

Cheers!

steven

[miguel m]

beautiful

[Wolfwood]

There might be a bug or two in the Uberlight code. Well not really a bug but where a Mantra Rendering and a RenderMan one don't match up. I compared the two using a simple Houdini scene and a hand written RIB which I rendered in BMRT and it seemed "right".

I forgot to mention how the blockers work. The Uberlight in RenderMan uses defined CoordinateSystems as blockers. But in VEX there is no RI_CoordinateSystem call so I used otransform(...) instead. So to use a blocker just use a Geometry Object's name. See the attached file.

A good reference when using a blocker is a XY Grid with a size of 1. (Make sure that the Obj doesn't render by have the render flag set to a Add Sop).

jim.

uberExample.zip

[Wolfwood]

Hmmmm a couple of additional things concerning the light rig. Since it is made up of different types of curves it will disappear from the viewport if you have VEX Shading mode on. (I just turn the its display flag off when in VEX Shading). However you can see the uberlight at work in VEX Mode so all is good.

Another little trick is to have the Uberlight Rig "Look At" a null object. Then in SHOPs use the distance expression in the "UI Light Scale" parameter.

distance(ch("/obj/$OS/tx"),ch("/obj/$OS/ty"),ch("/obj/$OS/tz"),ch("/obj/null1/tx"),ch("/obj/null1/ty"),ch("/obj/null1/tz"))

So instead of manually having to change the Light Rig's scale it is done by moving the null object. So now you can just move the null somewhere and get a rought idea what color the light is going to be without even having to hit the render button.

jim.

[Wolfwood]

I'm going to turning this into a OTL for Houdini 6.

Besides being just VFL code, I'm also create VOP network so people can easily extend it right from Houdini. (Like add support for multiple blockers.)

I'm going to add some additional features too, mainly the ones Kevin Borke talked about in the 2001 RenderMan course at Siggraph. But while I'm at it does anyone have any additional features they want?

Perhaps a directional light? (Solar in renderman speak)

Spline falloff support? Create some sort of curve in CHOPs between 0 and 1 and have that control the light color/intensity over L.z. The 0 and 1 would be remaped to cuton and cutoff. So at 50% between the start and end of your light beam you could change its color, or make it brighter, etc.

Anything else?

jim.

(ps. Do any of you use Peter's UberShadow? or a modified version?)

[AndrewVK]

>>"Like add support for multiple blockers."

seems like

vector Pb1 = otransform(blockercoords,P1);

vector Pb2 = otransform(blockercoords,P2);

doesnt work in 6.0.242

Bug ???

[Wolfwood]

[EDIT]NOT A BUG, SEE BELOW[/EDIT]

I'm pretty sure its a bug. I won't know for sure until Sidefx's forums are back up.

I'll give it a go real quick.

From the mailing list

Charles Abou Aad saide

Anyone had problems with otransform?

I check the result and all it returns is the identity matrix, even

though my reference object

[Wolfwood]

Ok, I checked it out on 6.0.243

and otransform works....but not like it used to.

In 5.5 you could just specify the object's name in the objspacechg1 VOP. Howeven in 6, you must specify the entire path of the object.

In 5.5, simply model would do.

But in 6, you need to do /obj/model.

I assume this is because of the network inside of networks. Because you could have two objects of the same name within different networks.

While I agree with this change, I think SESI should put it in big bold letters somewhere.

jim.

[AndrewVK]

Works fine!!!

...time to change "Object Name" parameter type of

"space change to object" vop from "string" to "operator path"...

(taking into account "unquoted" problem )