Where can I find the daily apprentice builds ?

When connecting a group geometry inside a piece of geometry, there is an option to group by pattern and ‘transfer selection to pattern’. When I select some points and click on this button, the resulting pattern is ALL of the geometry's points, not my selection. What is wrong ?

JColdrick: you were right, stupid me ops:

I have a male model wearing a shirt.
Shirt is cloth object in Houdini.
Man is rigid body.
They have a collide relationship.

What happens ?

The shirt falls straight through the model…




How do I fix this ?

I don't understand how full liberty of movement (tumbling upside down and fully sideways) can be achieved with any of Houdini's tumbling methods. Take a look at tumbling in Blender to see how it should be done. Really, this is one of Houdini's weakest points…

It seems the culprit is a destruction routine in the shardgen Python code: whenever align<-> build is switched off, all shard geometry is destroyed and then remade when it is switched back on. It seems the dopnet registers the destruction of the shards, but doesn't immediately register the shard geo been made again. This is then why it doesn't display nor simulate.

This is really weird behaviour. I need a workaround since shards geo with Python code slows down aligning the hole so must be destroyed when switching.

Don't know if anyone wants to dive into this one.

Problems with my digital asset.

First how does it work ? There is a Python SOP on the obj level ('shardgen1')that has several parameters. First the align<->build parameter is toggled off. The screen shows two tubes that are used to position the spot for a hole in eg. a wall (here inside wall object on obj level). Then you toggle on align<->build and the wall appears with a hole in it. So far so good. Problem is, the script code inside the ‘shardgen’ SOP also creates a bunch of shards that sit inside the hole. They don't appear though (not anymore that is, yesterday all was going fine). What happens is this: when you go into the dopnet1 (inside shardgen1) and you mliddleclick on ‘shards’ Houdini tells you "no objects were processed on the last timestep'. This should be the about 2 hundred shards. (the visualisation of the shards is done after the dop stage through a dopimport SOP) When you click on the display flag of ‘shards’ or when you change any parameter everything recooks and the shards appear magically where they should be. So, why does it not (and it did before) cook the shards properly straight away ?

Hope this makes sense.

I am searching the docs for a way of setting a node's display flag from Python.
No luck as far.

Anyone know more about this ?

Some basic questions here.
First of all, in the accompanying .hipnc file you can see that geometry (the shards) is displayed twice in Houdini viewport, it also renders twice. This is once the original geometry, once that moved by the dopnet1.
Is this normal behaviour ? I suppose its just Houdini showing things at different levels of the network. But why does it also render? Is this also normal behaviour? I will have to turn that display flag off.

Now for the more important question: when rendering and in viewport, the texture I assigned to the shards does only show on the representation without dynamics (that from the geometry level) and not on the shards moving through the dynamics simulation. How do I set things up so that the moving shards get textured ?

*solved: referenced object as RBD before material was applied

I have made a Python SOP at object level that sets up a few hundred nodes for later use in the animation.
I do not want this script to be ran every time I change the frame counter. Is there any way, except for changing the script to see if it already ran, I can control the cooking conditions, like only on change of a certain parameter?

I am looking for a quick way to get print output from python so that I can monitor my variables during program execution ?

Thanks so much for the clear and helpful replies!

One last question: can I create geometry from scratch in python by hooking up points and primitives ?

Ah, I see.
And there is no way of programming modifications so that they happen only at cooking time ?
Maybe by using hou.Node.cook ?

I mean, can I modify the point positions of my box or , sadly, not ?


With “cooking inside a SOP Node” you mean my box node that I want to modify, or do you mean I need a separate SOP Node? I am a bit confused…

It is set to Python.

I suppose your answer holds the key to solving this problem. I don't get it to work yet though. I set current node to my box node:

hou.cd(“/obj/geo1/box1”)

Then try to modify it:

hou.pwd().geometry … .setPosition((0,0,0))

And still get a GeometryPermissionError: read-only.


Is there any other method for setting pwd() that does work ?

When I try to change the positions of the points of a cube, I bump into a GeometryPermissionError. It seems all geometry nodes have their geometry in a read-only state. Methods to change the permissions (removePermission/setPermission) are not implemented yet. As such the Python scripting model seems not usable at all.
This combined with the many not-yet-implemented functions and the early state of the documentation makes Python difficult and cumbersome to use.
Also are their any functions for creating geometry (vertices, edges, faces) from scratch or adding to existing geometry. I believe not. Coming from Blender that supports even OpenGL in-viewport through Python this is a big step back in terms of functionality.
Pity.

I try to add a Script SOP to my scene, but when I load in my script the script node signals an error:

Python error: file “<stdin>”, line 1
/home/groost/houdini/shards.py
Syntax Error: invalid syntax.

With the little error pointer on the first / in the path.



This seems to point to a bug in Houdini, methinks…
Not sure. Any help?

Coming from Blender, which also has Python support, I wonder if Houdini makes it possible to draw through OpenGL or through other means, lines and points, rectangles,… straigth into a viewport ?
This makes possible tool gui.