Hi all,

I've got this field of grass(made with lsystems) and alpha maps of the same size. I'm trying to read in the value off the alpha map then multiply this value with the number of generations. I'm hoping this will have the effect of altering the size of the grass in relation to the alpha map. I stuck with reading in the map and also I've somehow got to get the value relating to the right l-system in the field. Kinda hard to explain that. Hope you understand.

Thanks for any help in advance.

Henster

Hi,

Can you use pic() or tex() to read the alpha map? The pic() will read from COP, while the tex() will read from file on disk.

eg. pic(“/comp/ice1/color1”, $BBX, $BBZ, D_CA)

Hope that helped.

Thanks for the reply UsualAlex. I've looked at the pdf documentation and you've just D_CA to refer to the colour type. Where can I find this documentation?

Cheers
Henster

Ahem, I've hit another problem. I can't set up bounding boxes. Do you do it in the expressions window?

Do you think someone could give me an example?

Thanks
Henster

Hi Henster,

You can simply set up the bounding box in at least 3 or 4 different ways in Houdini. It's all depending on what you want to do with the bounding box information.

SOP way:
You can simply append a Box (or Sphere) SOP after any of your geometry SOP, this will automatically set up a bounding box (or sphere) for you.

Expression way:
You can apply $BBX, $BBY, $BBZ in your SOP's channel field (where you type in your numbers and stuff) in SOP like Transform SOP and such. Note that not every SOP will support this.

Or you can use bbox() to grab the bounding box of the SOP that you want to set up the bound.
eg. bbox(“../mysop/xform101”, D_YSIZE)
Please type in “exhelp bbox” in your textport for help.


Hope that helped.