An Houdini passes system

Switching regularly between Houdini and XSI, I often miss the Softimage passes system. Houdini gives us several options to render the same animation with different “render settings” in one hip file, but nothing so fast and easy to manage than the XSI passes system.

As this little diagram illustrate ( made with dial, a simple but very usefull free tool) , it looks like it is possible to build an HDA to mimic Softimage system in Houdini (if we considere that an object node with an “object merge” sop looks like a partition).

The HDA interface is there to allow the user to quickly set those “object merge/partition” with a material and some rendering option (only Phantom for the moment to mimic the primary ray toggle we could add using an override on an XSI partition).

The trick is to limit the scope of the mantra rop used by this HDA to only the “objects merge/partitions” from this HDA. The way I found is to use a null named “out_passe” below the object merge and a null named “not_passe” not connected and used for render and display.
Then I use a pre-render script like this one :
“opset -r on /obj/`opname(“../..”)`/partition_0/out_passe”.
and a post-render script like this :
“opset -r on /obj/`opname(“../..”)`/partition_0/not_passe”.

There is maybe a simple way to limite the scope of a rop to only one object node but I was too leasy to investigate more :-p.

Here is a little demo of an early version of this HDA.

For now each “passes” has its own renderer like in XSI before V6. A global/local system for the render options could be possible but it is so easy to link parameters and build its own rendering panel in Houdini that I don’t want to add such a feature.

To finished here is a picture of a famous french point break. No relation with the passe sytem, but I just don’t want that you call the police !

Choose your job

Some people got a job in front of a screen, others in front of the ocean.

Here is some people with a job in front of the ocean (and very good in their job dont you think ?).

sticky bob

The initial goal was to create a cartoon collision deformer like in the Pixar paper “Acting with Contact in Ratatouille – Cartoon Collision and Response”.

Trying to figure out how to achieve this effect, my first “not very controled experiments” gives some kind of interesting results. Not sure if it could be usefull in production, but at least it is fun to play with at home .

Here is a first test of this C++ custom deformer using bob, my new crash test dummy (before bob I was using pingouins…).

Sticky bob.

frenchdog :: hello blog()

frenchdog :: hello blog()

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