evaluating python script every frame

[Johannes Saam]

Hey dudes,

I know its sounds simple but i am not really sure how to attack a python problem i have efficently.

I have camera information stored in one single file for a sequence. Now i wanna create a custom camera hda that reads that file. I tried different ideas so far without enough success. For example using an expression to setWorldTransform of a camera node inside my hda. Worked great but as soon as i make that otl live, changing its content created a permission error. I tried a python script in the hda onUpdate... but change of time does not seam to trigger it. I know i could wirte functions in the hdaModule() but how would that update it?

So the basic question is, i have ONE file for a sequence inside there is a world space matrix and some other parameters, i have a python API to read the file and get the values out. How do i go about creating an otl that is fast and updates every frame.

Thanks!

jo

[graham]

Take a look at Python Objects. They allow you to set the world transform for the node when it cooks.

[Johannes Saam]

but would it recook? Do i create a hidden time dependent attribute?

Take a look at Python Objects. They allow you to set the world transform for the node when it cooks.

[graham]

To make a node time dependent if it isn't already you just need to have a call to hou.frame() in your cook code. Since you are most likely already doing this in order to index into your sequence you shouldn't have to worry.

[Nerox]

I know it has been a month since the last reply, but would it be an option to load the file in to memory? Like hou.session, or a sub-routine that reads in the data from the file and builds a animation curve?

Whats the point of reading data from it on every frame? Unless the file is adjusted by another process...