Hi all,

I posted a few weeks ago regarding a current project, realtime music visuals in Houdini. Thanks to all who replied. However whilst striving to learn Houdini in a matter of weeks I have come across a few other problems:

How could I use the translateY attribute of a particle to control something indirectly at sops level? Basically I want the position of a particle to drive the generations of an L-system. I have noticed that the Particle sop has $TX $TY $TZ local variables but am unsure how to utilise them.

Also, this may be a bit basic but I am trying to vary the transparency of a shader in shops layer by adjusting the alpha channel but nothing appears to happen, why is this?

Cheers

Andy

Hello Goku,

Not sure how you plan to use a position vector to control L-system generations but I can help with $TX, $TY and $TZ.

They are local variables. So they only effect geometry inside that SOP. By the sounds of it you want to get this information into other SOPs ( eg the L-system SOP) you want the point() function. Use it like this:

point(“/obj/geo/particle1”,$PT,“P”,0)

This gets the X value for each point (particle). You have to play with this one.. very useful it is to.

go to the textport and type- exhelp point

Good luck!