basic HDK question

[bhenriksson]

I'm new to both C++ and HDK. I manage to get my compiled SOPs into houdini but it return an empty geo even with when the cook function consists of a simple `return error()`. I'm guessing the `gdp` is automatically used as output geo but how do I set this to be the old geo? Do I need to initialise anything to hook things up?

grateful for any help

Thx

[edward]

What do you mean by the "old" geo? The "gdp" is the output geo. In SOPs, there is no built-in support for iteration. If you want to say take the geometry from the last frame, then you have to maintain that yourself.

[bhenriksson]

What do you mean by the "old" geo?

With "old" I meant "incoming". I got one incoming node, I thought it's geo was used as the `gdp`.

[edward]

You call duplicateSource() with the input number that you want to copy into the gdp. See the SOP_Flatten.C example file

[bhenriksson]

Thanks mate.

So as I understand it now the gdp is by default empty?

[edward]

Yes, as you've no doubt found out by now.