link rotation to direction

[AlbertoDr]

Hi

I'm a new user of Houdini. I was wondering how create expression to constraint objects, in particular my problem now is that I've animate position and rotations of a null, and I'm trying to link these values in a fan force inside a dopnet node (actually an AutoDopNetwork node for pyro simulation). For the positions values it's easy, instead I don't know how convert the rotation into direction of the fan.

I don't expect to find something like the constraint in Maya, but I'm really concerning how to animate a force, if everytime I'm forced to simulate for see my fan animation.

thanks

Alberto

[AlbertoDr]

Hi

if someone is curious, a dude in an other forum give me one solution.

fan_dir_x => (vector4(0,0,1,0)*optransform("../null1"))[0]

fan_dir_y => (vector4(0,0,1,0)*optransform("../null1"))[1]

fan_dir_z => (vector4(0,0,1,0)*optransform("../null1"))[2]

where vector4(0,0,1,0) is the reference vector that you have to rotate.