Expression madness

[Pancho]

Hi there, actually I'm trying to group edges by point positions. This isn't working so far at all. But as a first step I'm trying to group points by expressions.

 

While @P.x>0.1 works, (@P.x+@P.z)>0.1 doesn't. A - ha?!?!

 

@length{@P.x,@P.y,@P.z}>0.1

@length(@P.x,@P.y,@P.z)>0.1

@length{@P}>0.1

@length(@P)>0.1 work neither.

 

Well, don't quite get it and Google doesn't find anything either. Anyone who can shed some light? If there's a way to select edges like this directly I'd be also glad to get some info.

 

Only found this thread and wonder whether this is still state of the art. http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=19493 Cheers Tom

Edited August 4, 2015 by Pancho

[Atom]

Remember, you can not use variables inside of braces, only constants. Try using the VEX function set instead.

 

It also seem like you are trying to use VEX code in an hScript field of the Group node.

They are different languages and are not compatible.

Edited August 4, 2015 by Atom

[Pancho]

Thanks for the tip, but $TY just let's my model disappear.

 

How would I do that? Build a group based on vector length and y-Point Position? Can't be so hard if one speaks expression or hscript fluently?

 

: )

ScreenShot001.bmp

[mestela]

Here's a few different ways of selecting edges.

 

 

group_edges.hipnc

[Pancho]

Woooooooo - ooooooooow!

 

Thanks sooooo much! That's really a lot of useful information I can pull out of this scene!

 

In ten minutes I'll know whether I can solve all the problems I got in my scene!

 

Very generous!

 

Cheers

Tom

[amm]

Hello Pancho,

just to add another way. If you prefer to use nodes, you can use method decribed here . in post  by mawi.

Or just use bind export in attribute vop to export some attribute, which you'll use later in 'combine' tab of Group SOP. If you have some complex criteria, expression probably isn't the best way....

Edited August 4, 2015 by amm

[Pancho]

Hi Anto,

thanks for the tip. Seems like you aren't struggling as much as me. : )

Some things over here seem to be over complicated, while the procedural modeling looks much smoother and sooo much faster than ICE topology. Miss those simple "Get closest location" nodes .....

Cheers

Tom

[amm]

Functionality of Softimage ICE "Get closest location" is described by conjunction of 'XYZ distance' and 'Primitive Attribute'. Let's say that XYZ distance' is 'get' part, while 'Primitive Attribute' is similar to ICE 'UV to location', while 'Primitive Attribute' works on meshes, too - 'uv' is defined by borders of each polygon, in case of mesh. If these two are querying different objects, then there's ICE 'reinterpret location to new geometry' functionality. 'XYZ distance' also tells you from which primitive is 'getting'.

[mestela]

Ahhh, cool trick! I knew you could get group membership in vex with @group_mygroupname, I didn't know you could set it that way too. Eg, group all points with ptnum greater than a slider threshold:

 

if (@ptnum>chi('threshold')) {
 i@group_mygroup=1;
}

 

To get visual feedback, hit '9' in the viewport (or click the 'display group and attribute list' button on the right toolbar of the viewport, towards the bottom), and make sure its in a mode that matches your wrangle mode.

 

Animated gif (click to play)

 

 

 

Edited August 4, 2015 by mestela