Time to learn Houdini! Despite my growing trepidation related to the constant reassurances that it will be fun after a grievously long learning curve, I went into this first tutorial eager to learn. I tentatively want to declare my specialization as lighting and texturing. I still have a very long ways to go in this area, and in fact I’m really just getting started. But I’ve heard from everyone that Houdini is the software to use for this and I’m excited to see what I can do.
Here’s some of the most important notes I took during the beginning of the session.
Vocab
obj > object
img > compositing
ch > animation
mat > materials
shop > shaders
out > rendering
stage > USD (?)
tasks > pipeline
SOP: old term for geo –Surface OPerators
OBJ: object
DOP: Dynamics OPerators
ROP: Rendering OPerators
VOP: Vex OPerators > Vex: Houdini scripting language, similar to Mel.
$HIP > file output
$OS > object name
bgeo: Houdini file format that can save anything. bgeo.sc = compressed
1 unit = 1 meter
About half an hour in, I was sure I was lost because Mehdi added a geometry node to his sphere, while I could not find the node “geometry” listed and only had more advanced options-
-but I realized quickly that it came down to being in the object context rather than the SOP context- the SOP context has many more options as most of the work is done there. I found a couple times that when I was unable to follow along it was because I was in the OBJ rather than SOP context- for example, trying to place a file node.
I brought in my own OBJ file to follow along with the file SOP node- a set of dice I’d used in my performance animation:
I was originally unsure why they are wireframe, and quickly realized that toggling between these options-
-allows for different levels of visibility.
After some trial and error I managed to merge my dice and sphere objects, and scale them down when I realized that a unit is equivalent to a meter. This should be important knowledge down the road.
Moving onto the next Houdini scene. I was stymied for a while because Mehdi, when creating a ROP Geo node for his torus, saved his project under $HIP, and I had changed my project’s path to a specific folder for schoolwork. I kept trying to change the file output to this folder and was unable to locate the geo. However, I went back into the tutorial the next day and realized, upon listening more closely, that $HIP does not necessarily mean any kind of Houdini preferences folder, instead it refers to whichever path the file is saved in, therefore there is no need for me to change the $HIP path to my own- it’s already there. Sure enough I saved it under $HIP and was able to locate it in the geo folder of my project.
$HIP can be a variable, $HIPNAME cannot.
The only other problem I ran into was all the way at the very end.
Somehow I could not stop the raised points from being deleted when I merged the roof with the main cabin.
The way I ended up solving this was simply re-creating the transform node for the points. It still wasn’t working, but I deleted and re-attached the connector and somehow that changed everything. I am not sure how this worked. To me, the tree looks exactly the same before and after I did this.
I moved on to Mehdi’s bonus project: building the cabin with pronounced wood slats. I was able to remake the entire cabin, but for some reason my booleans for the windows weren’t working, and I’m sure that although the cabin looks good there is something mathematically off. I am sure that the Q&A session will provide me with more insight.
Additional questions-
Why create a transform node instead of just working in the viewport?
How does the divide node work?
I’m still not sure what the delete node actually does.