retrieve associated information with halfspaces after a halfspace intersection

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retrieve associated information with halfspaces after a halfspace intersection

Maarten Moesen

Dear CGAL community,

 

From a large vector of planes (halfspaces), in which each plane has some information attached, I’d like to create a convex polyhedron using

CGAL::halfspace_intersection_3() and halfspace_intersection_with_constructions_3().

How can I efficiently identify in the resulting polyhedron which planes where selected, so that I can efficiently retrieve the information associated to each selected plane?

 

Best regards,

 

Maarten

--

Maarten Moesen, PHD

Polymer Physicist Computational Modeling

 

HUNTSMAN (Europe) BVBA

Everslaan 45

B-3078 Everberg

Belgium

VAT: BE - 0468.807.829

 

Office Phone: 0032 (0) 2 758 9962

 

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Re: retrieve associated information with halfspaces after a halfspace intersection

Sebastien Loriot (GeometryFactory)
With the current code there is no entry in the API. However it should
not be not hard to do it. Indeed, looking at the
halfspace_intersection_with_constructions_3.h for example, you'll see
that when a new face is created in build_dual_polyhedron (which is
building the dual of the dual, i.e. the final intersection) we iterate
over vertices of the convex hull of the dual (one vertex = one plane)
so we could add a property in the API to add that information.

Best regards,

Sebastien.

On 2/22/19 8:19 AM, Maarten Moesen wrote:

> Dear CGAL community,
>
>  From a large vector of planes (halfspaces), in which each plane has
> some information attached, Iā€™d like to create a convex polyhedron using
>
> CGAL::halfspace_intersection_3() and
> halfspace_intersection_with_constructions_3().
>
> How can I efficiently identify in the resulting polyhedron which planes
> where selected, so that I can efficiently retrieve the information
> associated to each selected plane?
>
> Best regards,
>
> Maarten
>
> --
>
> Maarten Moesen, PHD
>
> Polymer Physicist Computational Modeling
>
> HUNTSMAN (Europe) BVBA
>
> Everslaan 45
>
> B-3078 Everberg
>
> Belgium
>
> VAT: BE - 0468.807.829
>
> Office Phone: 0032 (0) 2 758 9962
>

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RE: [EXTERNAL] Re: retrieve associated information with halfspaces after a halfspace intersection

Maarten Moesen
Dear Sebastien,
Dear CGAL community,

Thank you for your answer. Indeed, it doesn't look too hard.

I'm now having a similar question about convex_hull_3: what is the recommended way to keep track of the vertices in the convex hull?
For example: if I have originally a large vector or list of points, possibly with some info associated with them. How can I efficiently determine which points are in the convex hull? Can I access from the resulting convex polyhedron the original iterator? Can I associate some info to each point?

Best regards,

Maarten
-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Sebastien Loriot (GeometryFactory)
Sent: Friday, 22 February, 2019 09:50
To: [hidden email]
Subject: [EXTERNAL] Re: [cgal-discuss] retrieve associated information with halfspaces after a halfspace intersection

With the current code there is no entry in the API. However it should not be not hard to do it. Indeed, looking at the halfspace_intersection_with_constructions_3.h for example, you'll see that when a new face is created in build_dual_polyhedron (which is building the dual of the dual, i.e. the final intersection) we iterate over vertices of the convex hull of the dual (one vertex = one plane) so we could add a property in the API to add that information.

Best regards,

Sebastien.

On 2/22/19 8:19 AM, Maarten Moesen wrote:

> Dear CGAL community,
>
>  From a large vector of planes (halfspaces), in which each plane has
> some information attached, I'd like to create a convex polyhedron
> using
>
> CGAL::halfspace_intersection_3() and
> halfspace_intersection_with_constructions_3().
>
> How can I efficiently identify in the resulting polyhedron which
> planes where selected, so that I can efficiently retrieve the
> information associated to each selected plane?
>
> Best regards,
>
> Maarten
>
> --
>
> Maarten Moesen, PHD
>
> Polymer Physicist Computational Modeling
>
> HUNTSMAN (Europe) BVBA
>
> Everslaan 45
>
> B-3078 Everberg
>
> Belgium
>
> VAT: BE - 0468.807.829
>
> Office Phone: 0032 (0) 2 758 9962
>

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Re: [EXTERNAL] Re: retrieve associated information with halfspaces after a halfspace intersection

Sebastien Loriot (GeometryFactory)
Would this be sufficient:
https://doc.cgal.org/latest/Convex_hull_3/Convex_hull_3_2extreme_indices_3_8cpp-example.html

or you need the convex hull as well?

Sebastien.

On 2/22/19 11:29 AM, Maarten Moesen wrote:

> Dear Sebastien,
> Dear CGAL community,
>
> Thank you for your answer. Indeed, it doesn't look too hard.
>
> I'm now having a similar question about convex_hull_3: what is the recommended way to keep track of the vertices in the convex hull?
> For example: if I have originally a large vector or list of points, possibly with some info associated with them. How can I efficiently determine which points are in the convex hull? Can I access from the resulting convex polyhedron the original iterator? Can I associate some info to each point?
>
> Best regards,
>
> Maarten
> -----Original Message-----
> From: [hidden email] <[hidden email]> On Behalf Of Sebastien Loriot (GeometryFactory)
> Sent: Friday, 22 February, 2019 09:50
> To: [hidden email]
> Subject: [EXTERNAL] Re: [cgal-discuss] retrieve associated information with halfspaces after a halfspace intersection
>
> With the current code there is no entry in the API. However it should not be not hard to do it. Indeed, looking at the halfspace_intersection_with_constructions_3.h for example, you'll see that when a new face is created in build_dual_polyhedron (which is building the dual of the dual, i.e. the final intersection) we iterate over vertices of the convex hull of the dual (one vertex = one plane) so we could add a property in the API to add that information.
>
> Best regards,
>
> Sebastien.
>
> On 2/22/19 8:19 AM, Maarten Moesen wrote:
>> Dear CGAL community,
>>
>>   From a large vector of planes (halfspaces), in which each plane has
>> some information attached, I'd like to create a convex polyhedron
>> using
>>
>> CGAL::halfspace_intersection_3() and
>> halfspace_intersection_with_constructions_3().
>>
>> How can I efficiently identify in the resulting polyhedron which
>> planes where selected, so that I can efficiently retrieve the
>> information associated to each selected plane?
>>
>> Best regards,
>>
>> Maarten
>>
>> --
>>
>> Maarten Moesen, PHD
>>
>> Polymer Physicist Computational Modeling
>>
>> HUNTSMAN (Europe) BVBA
>>
>> Everslaan 45
>>
>> B-3078 Everberg
>>
>> Belgium
>>
>> VAT: BE - 0468.807.829
>>
>> Office Phone: 0032 (0) 2 758 9962
>>
>
> --
> You are currently subscribed to cgal-discuss.
> To unsubscribe or access the archives, go to https://urldefense.proofpoint.com/v2/url?u=https-3A__sympa.inria.fr_sympa_info_cgal-2Ddiscuss&d=DwID-g&c=XEmjTyjfAPcP2RtAp-6FGA&r=m_cDzmT5gx2T28-wSEGolLNtn-S-ReoPoEIWT7yrZso&m=TuWVJou7bxkrmeicvRgCHkeSePSF-004JHholzs0xC4&s=yqFO0y5NWJn6LDPWxCcvhks_OMacWN4c6IxiHIjvdSo&e=
>
>
>

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RE: [EXTERNAL] Re: retrieve associated information with halfspaces after a halfspace intersection

Maarten Moesen
Thank you, Sebastien.
I overlooked this feature because I was still working with version 4.10 (and its documentation). So I'm planning to upgrade soon šŸ˜‰

Nice weekend!

Maarten

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Sebastien Loriot (GeometryFactory)
Sent: Friday, 22 February, 2019 11:43
To: [hidden email]
Subject: Re: [cgal-discuss] [EXTERNAL] Re: retrieve associated information with halfspaces after a halfspace intersection

Would this be sufficient:
https://urldefense.proofpoint.com/v2/url?u=https-3A__doc.cgal.org_latest_Convex-5Fhull-5F3_Convex-5Fhull-5F3-5F2extreme-5Findices-5F3-5F8cpp-2Dexample.html&d=DwICaQ&c=XEmjTyjfAPcP2RtAp-6FGA&r=m_cDzmT5gx2T28-wSEGolLNtn-S-ReoPoEIWT7yrZso&m=i8LVh5KRPscA4QVq8VepWDjbZG43LNRri4XyM97xaP0&s=J8TCWGY5Bkv78ABJorZYHFcFI6pkFyH9H7RFYgLdrUE&e=

or you need the convex hull as well?

Sebastien.

On 2/22/19 11:29 AM, Maarten Moesen wrote:

> Dear Sebastien,
> Dear CGAL community,
>
> Thank you for your answer. Indeed, it doesn't look too hard.
>
> I'm now having a similar question about convex_hull_3: what is the recommended way to keep track of the vertices in the convex hull?
> For example: if I have originally a large vector or list of points, possibly with some info associated with them. How can I efficiently determine which points are in the convex hull? Can I access from the resulting convex polyhedron the original iterator? Can I associate some info to each point?
>
> Best regards,
>
> Maarten
> -----Original Message-----
> From: [hidden email] <[hidden email]> On
> Behalf Of Sebastien Loriot (GeometryFactory)
> Sent: Friday, 22 February, 2019 09:50
> To: [hidden email]
> Subject: [EXTERNAL] Re: [cgal-discuss] retrieve associated information
> with halfspaces after a halfspace intersection
>
> With the current code there is no entry in the API. However it should not be not hard to do it. Indeed, looking at the halfspace_intersection_with_constructions_3.h for example, you'll see that when a new face is created in build_dual_polyhedron (which is building the dual of the dual, i.e. the final intersection) we iterate over vertices of the convex hull of the dual (one vertex = one plane) so we could add a property in the API to add that information.
>
> Best regards,
>
> Sebastien.
>
> On 2/22/19 8:19 AM, Maarten Moesen wrote:
>> Dear CGAL community,
>>
>>   From a large vector of planes (halfspaces), in which each plane has
>> some information attached, I'd like to create a convex polyhedron
>> using
>>
>> CGAL::halfspace_intersection_3() and
>> halfspace_intersection_with_constructions_3().
>>
>> How can I efficiently identify in the resulting polyhedron which
>> planes where selected, so that I can efficiently retrieve the
>> information associated to each selected plane?
>>
>> Best regards,
>>
>> Maarten
>>
>> --
>>
>> Maarten Moesen, PHD
>>
>> Polymer Physicist Computational Modeling
>>
>> HUNTSMAN (Europe) BVBA
>>
>> Everslaan 45
>>
>> B-3078 Everberg
>>
>> Belgium
>>
>> VAT: BE - 0468.807.829
>>
>> Office Phone: 0032 (0) 2 758 9962
>>
>
> --
> You are currently subscribed to cgal-discuss.
> To unsubscribe or access the archives, go to
> https://urldefense.proofpoint.com/v2/url?u=https-3A__sympa.inria.fr_sy
> mpa_info_cgal-2Ddiscuss&d=DwID-g&c=XEmjTyjfAPcP2RtAp-6FGA&r=m_cDzmT5gx
> 2T28-wSEGolLNtn-S-ReoPoEIWT7yrZso&m=TuWVJou7bxkrmeicvRgCHkeSePSF-004JH
> holzs0xC4&s=yqFO0y5NWJn6LDPWxCcvhks_OMacWN4c6IxiHIjvdSo&e=
>
>
>

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