Thread Subject: intersections between 2 volumes

I wonder if there is an easy way to determine whether there is an intersection between two patches. Thanks!
Irina

"Irina Grigorova Grigorova" <grig76@gmail.com> wrote in message <h3uefd$dct$1@fred.mathworks.com>...
> I wonder if there is an easy way to determine whether there is an intersection between two patches. Thanks!
> Irina

Sorry, but no, there is not.

John

You need to give more informations:

-quad or triangular pathes?
-Do you have normals?

Anyway john is right, no easy way to do that.

Maybe this function can help you:

http://www.mathworks.com/matlabcentral/fileexchange/24631

"Irina Grigorova Grigorova" <grig76@gmail.com> wrote in message <h3uefd$dct$1@fred.mathworks.com>...
> I wonder if there is an easy way to determine whether there is an intersection between two patches. Thanks!
> Irina



Maybe this link could provide you more information of what you're trying to do.


http://www.mathworks.com/access/helpdesk/help/toolbox/map/index.html?/access/helpdesk/help/toolbox/map/polybool.html&http://www.google.ro/search?hl=ro&q=intersection+2+patches+patches+function+matlab&btnG=C%C4%83utare+Google&meta=&aq=f&oq=



Or look at the function patches in matlab:

In command window type:

>>doc patches

Sry the name of the matlab function is patch not patches.


Sry:(.

So type:

>>doc patch

Thanls! Ufh. Could not find a way to do that in the doc files.
Do you think there is a way to check whether a single point is in a patch (inside surface)?

Irina


"Sprinceana " <mihaispr@yahoo.com> wrote in message <h3v1tv$oa2$1@fred.mathworks.com>...
> Sry the name of the matlab function is patch not patches.
>
>
> Sry:(.
>
> So type:
>
> >>doc patch

"Irina Grigorova Grigorova" <grig76@gmail.com> wrote in message <h3v6ah$bfu$1@fred.mathworks.com>...
> Thanls! Ufh. Could not find a way to do that in the doc files.
> Do you think there is a way to check whether a single point is in a patch (inside surface)?
>

Polybool will not tell you if a point is inside a volume.
If you only care about a point inside a polygon, then
inpolygon will do very nicely, and you don't need the
mapping toolbox.

To find if a point is inside a convex domain, you can
use a tool like inhull, from the file exchange. But this
assumes that your domain be a convex volume. To
know if a point is inside a general non-convex surface
is more difficult.

One simple trick is to consider any ray that emanates
from the point to infinity. If it crosses the surface an
odd number of times, then the point is inside.

John

Hi John,

Can you please check your e-mail, I need an aswer to organize my work :-)

To find a point inside a non convex manifold you can use:

http://www.mathworks.com/matlabcentral/fileexchange/24631

It does use the ray tracing method but in slightly different way. Counting the number of interestction can be very tricky for points lying on edges/points of the surface.

http://giaccariluigi.altervista.org/blog/

Best regards Luigi

Thank you very much for all information!
Best,
Irina

"Luigi Giaccari" <giaccariluigi@msn.com> wrote in message <h3vff1$aps$1@fred.mathworks.com>...
> Hi John,
>
> Can you please check your e-mail, I need an aswer to organize my work :-)
>
> To find a point inside a non convex manifold you can use:
>
> http://www.mathworks.com/matlabcentral/fileexchange/24631
>
> It does use the ray tracing method but in slightly different way. Counting the number of interestction can be very tricky for points lying on edges/points of the surface.
>
> http://giaccariluigi.altervista.org/blog/
>
> Best regards Luigi