SOLID DIFFERENCE

Hi all,

I'm trying a solid diference between a prism and a set of little 'pipes inside of it.

The thing is that the difference only computes those pipes touching the prism boundaries but those pipes completely inside the prism are ignored.

Could any one bring some light on what's happening, please. It's annoying¡¡

In the image attached you will see difference made in red, but some pipes in green that did't compute.

It don't seem to be a graft issue, becouse it's working with more than one pipe in a time.

Maybe solid difference is not the apropriate component.

Please help¡¡

Attachments:

Picture 2012-08-14 18_55_37.png, 21 KB

Replies to This Discussion

Permalink Reply by Roig on August 14, 2012 at 11:37am

Resuming:

Can I make a solid difference if one objet is completely inside the other, with no boundary contact?

Permalink Reply by raja thomas on August 15, 2012 at 5:46am

I don't think so. Solid difference needs intersection. What do you actually want to do?

Permalink Reply by Roig on August 15, 2012 at 9:32am

Hi Raja,

I need to build a definintion of concrete. I need to have in one hand the cementous matrix and in the other the agregate.
I can model the agregate and the volume of the concrete specimen, and I need to substract the agregate volume from the cementous matrix prism, so there is no overlaping volume agregate/cement.
So the thing is to substrat a inner volume from a bigger one, but the inner one doesn't touch the boundaries of the bigger one (Think that it is floating in the middle of the bigger one). Autocad a 3DMAX can do that (and any other 3d program, but i don't know why Ican't in Rhino/GH)
Do you know why?
Thank you¡¡

Permalink Reply by Michael Pryor on August 15, 2012 at 9:39am

Rhino is not working with "solids", it represents solids as closed breps, which are a closed series of surfaces.

Permalink Reply by Roig on August 15, 2012 at 9:42am

Thanks Michael,

I can see that, but it is extrange not having an option, isn't it?

Permalink Reply by Andrew Heumann on August 15, 2012 at 9:43am

Rhino does not support this. All solids are represented with continuous, closed BReps - Boundary Representations - so if the surfaces of your volumes are entirely disjoint, they cannot be treated as part of the same solid.

You could easily just model them as separate volumes - aggregate volumes and cement volumes - and then measure them both and literally subtract one from the other to get the information you need.

Permalink Reply by Roig on August 15, 2012 at 10:00am

thank you all, I need the solid item as long as i need them to make a finite element calculation. I wanted to use GH to model the entire specimen, to avoid making solid operatio

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