How to create a point at the center of every primitive on a Grid SOP?

[zarti]

hi all ,

here are some 'ways' .

polyextrude , subdivide, curvesect and average-attribute 'techniques' could be new in this thread

, since i havent opened any uploaded file .

subdivide and average-attribute results seems to give a different but more 'natural' look when primitives are irregular .

pointAtZenter.hipnc

--

oh , and the "Lets Exchange Together ." is my favorite song here . =)

as i have done before , i wd again strongly suggest to SESI to spend some of their precious time and energy in this topic .

i do know nothing , but have a feeling that that this will change .. ..

.cheers

Edited January 8, 2012 by zarti

[magneto]

Awesome info guys.

@zarti, what did you do for this since you said you have done this before? Just curious.

If this small but enthusiastic community helps, this would be done in a way no one has ever seen before.

It's a double edge sword for Sidefx. Yeah it might take some of their time, but also take some weight off their shoulders by not having to add that feature a specific digital asset is filling.

Also what's better than getting tools from your own very users who has the best interest for the software.

There are some very smart and experienced users here. It would be a shame to have all this potential isolated from the base talent IMO.

[sleepstreamer]

Obvious solution, but, Foreach SOP?

pointatcenter.hip

[hopbin9]

Nice one. I totally forgot about the $CEX/$CEY/$CEZ variables.

[jim c]

Couldn't you use a POP net, feed in the geo, birth for 1 frame, and have the particles source to the center of each prim? I've used that before for quad like shapes and it works OK.

attached a hip file

centerpoints.hipnc

Edited January 13, 2012 by jim c

[magneto]

Thanks Jim, that's a very cool method

[DASD]

Update:

A new awesome method is to use an Attribute Wrangle set to "Run Over: Primitives" with the following code:

 

addpoint(0, @P);
removeprim(0, @primnum, 1);

 

 

First line adds a point to the center of every primitive. (I believe it uses the point average for the center).

The second line is optional and removes the original primitives.

 

Original thread:

https://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=35541

Edited September 15, 2015 by DASD

[jwoelper]

On 9/15/2015 at 3:34 PM, DASD said:

That's by far the best+fastest way, thanks!

If you want to keep the normals (this method is super handy for placing stuff later I think):
 

int pt = addpoint(0, @P);
removeprim(0, @primnum, 1);

setpointattrib(0, "N", pt, @N);

 

 

On 9/15/2015 at 3:34 PM, DASD said:

 

Update:

A new awesome method is to use an Attribute Wrangle set to "Run Over: Primitives" with the following code:

 

 

First line adds a point to the center of every primitive. (I believe it uses the point average for the center).

The second line is optional and removes the original primitives.

 

Original thread:

https://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=35541

 

[animatrix]

It's the simplest method but not the fastest.

If you want to perform this operation the fastest, you need to pre-generate your points using Point Generate SOP (nprims()) and then move each point to the center of each primitive using the second input as the reference.

That way you avoid the geometry creation and deletion operations, both of which are very expensive. Creating points using Point Generate SOP is extremely fast, since it creates all points at the origin.

[woodenduck]

attrib wrangle set to run over prims...

addpoint(0, @P);
removeprim(0, @primnum, 1);

[jwoelper]

On 8/18/2017 at 5:12 PM, pusat said:

It's the simplest method but not the fastest.

If you want to perform this operation the fastest, you need to pre-generate your points using Point Generate SOP (nprims()) and then move each point to the center of each primitive using the second input as the reference.

That way you avoid the geometry creation and deletion operations, both of which are very expensive. Creating points using Point Generate SOP is extremely fast, since it creates all points at the origin.

Thanks for the insight!