Channel Wrangle with Geometry CHOP as input?

Forums Technical Discussion Channel Wrangle with Geometry CHOP as input?

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jpparkeramnh: Member; 178 posts; Joined: Jan. 2013; Offline

Oct. 11, 2019 10:12 p.m.

Scratching my head on this…

What do I set the parameters on a Channel Wrangle CHOP to in order to modify point position data from a Geometry CHOP? I want to set it up so that the code can be similar to a Point Wrangle SOP.

I can't find a clear hint in the docs on how to do this.

Cheers,
Jon


jpparkeramnh: Member; 178 posts; Joined: Jan. 2013; Offline

Oct. 11, 2019 10:39 p.m.

BTW, I'm doing this purely in order to run VEX in 64 bit precision, which is supported only in CHOPS and Lens shaders at the moment.


tamte: Member; 8524 posts; Joined: July 2007; Offline

Oct. 11, 2019 10:53 p.m.

if you are importing geometry as Static
and you need just Position as you said, then the most convenient is Over Samples And Evert T/R/S
then you can do something like this:

@t += {0,1,0};
@t += noise(@t + @Time);

etc…

Attachments:
channel_wrangle_geo.hip (81.3 KB)

Tomas Slancik
FX Supervisor
Method Studios, NY


jpparkeramnh: Member; 178 posts; Joined: Jan. 2013; Offline

Oct. 11, 2019 11:18 p.m.

Answer that I currently can see is…

Bring in with a Geometry CHOP set to Animated mode, followed by a Reorder CHOP set to “Numeric Suffix Sort”, then a Channel Wrangle CHOP set to “Over Samples and Every Nth Channels” and name everything there appropriately.


jpparkeramnh: Member; 178 posts; Joined: Jan. 2013; Offline

Oct. 11, 2019 11:22 p.m.

Thanks Tomas, your static method probably works better than my convoluted method above…


jpparkeramnh: Member; 178 posts; Joined: Jan. 2013; Offline

Oct. 11, 2019 11:23 p.m.

Tomas, is there a way to get the iteration number in that mode?

Edited by jpparkeramnh - Oct. 11, 2019 23:24:10


tamte: Member; 8524 posts; Joined: July 2007; Offline

Oct. 11, 2019 11:36 p.m.

jpparkeramnh
Tomas, is there a way to get the iteration number in that mode?

it'll be in variable called I so :

vector r = rand(I);;
@t += r * .1;

also your input can be animated, the Static mode is just how they are read to chops, Static is one frame at a time, Animated would try to pull whole frame range, which unless you want to do timedepenent operations may be overkill

Edited by tamte - Oct. 11, 2019 23:38:02

Tomas Slancik
FX Supervisor
Method Studios, NY


jpparkeramnh: Member; 178 posts; Joined: Jan. 2013; Offline

Oct. 11, 2019 11:56 p.m.

This method doesn't seem to evaluate time correctly, which is OK in my specific case but doesn't seem very flexible. I need to access string attributes from a geometry object which don't import into CHOPS. See example.

Attachments:
Chops_example.hipnc (141.4 KB)


tamte: Member; 8524 posts; Joined: July 2007; Offline

Oct. 12, 2019 12:30 a.m.

I'm not sure how point() evaluates geo when called from chop context so it may be an issue with strings, unless you have specific set of strings and can refer to them through integer lookup, which you can pass to chops as a channel

Tomas Slancik
FX Supervisor
Method Studios, NY

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