Solaris instance lights and attribute variation

In Solaris we can instance lights onto points.
Make sure your points have  N & Up attributes, like you would with any instanced geo.

The more interesting stuff will be the intensity, exposure, "color" etc.

I know there's a post about this on Matt Estela's CGwiki, but I *think* it applies to an older version of Houdini/Solaris & the instancing method they use there is different - "reference" instead of point instancing. Never sure which is actually better or more efficient!

But how do we access them?? Here's a list of the stuff we can access (taken from the SideFX website)

Primvars

In Solaris/USD, you have access to several light-specific primvars. You can use attributes on the scatter points to drive these primvars. Here’s a list of the available primvars:

• intensity (intensity)

• exposure (exposure)

• width (width)

• height (height)

• color (color)

• radius (radius)

• color temperature (colorTemperature)

• diffuse multiplier (diffuse)

• specular multiplier (specular)

Note that width, height and radius are only available with area lights, while the remaining primvars are available for any kind of light source.

SideFX recommends using Attribute Adjust sops to access these attribs. They're a bit neater and user friendly than wrangles I suppose!

Below is how you use it... plug your points into the Attrib Adjust and type this into the name:

`encode("light:color")`

Don't forget the back ticks - ` `

The same applies to Attribute adjust float, for something like Intensity.. `encode("light:intensity")`

Also.. if you want to do stuff to these attributes in a wrangle (after they've been created), they get given a funky name, but these can be accessed normally

For instance (lol), here i'm multiplying the intensity of the lights with the speed at which they move at in a wrangle.

I'm not sure if the assigned name is the same each time so do check... 

geometry and material variants, instancing in solaris

Variant workflow. Use the Component builder + Geo Variants to build some variants. You'll use the Component Material node to create the mat variants, then packaged them out with the component output. Bake this as a USD.

 

Load your cached out USD. Attach an "explore variants" node and set the mode to explore. Set spacing to zero so they're all at the origin.

Then plug it into an Instancer. Specify the primitives you want to prototype (use in instancer). Make sure you UNTICK "Only Copy Specified Prototype Primitives". The rest is as normal (eg make some points inside the instancer and give it an index attribute).

Now all of your variants are in play.

This seems a bit longwinded, but I guess it does work and fits within a pipeline a bit nicer? It also works nicely with the variant systems that exist in Houdini/Solaris.

BONUS - if instead of using the Instancer in "Point Instancer" mode, you use "Instanceable Reference", you gain access to each and every instance. If you do this, you can actually use the Set Variant nodes to change particular instances, eg. you switch one of them to be a pig and make it red instead of green. Performance does take quite a big hit if you do this though. 

instance ass files (not paths)

use instancefile to access geo saved somewhere...

in a point wrangle - 

  s@instancefile=chs("path");

now with the geo node, you gotta add the instance tab and turn on fast instancing.

instance path

Say you have some points and you want to instance an object from disk to them..

in a point wrangle-

 s@instancepath=chs("path");

create the input box and type in the path of your object eg: c:\dave\ball.obj

beneath the point wrangle, add an instance node. ta da!