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Questions tagged [polyhedra]

84 questions
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Saving Nef polyhedron as Polyhedron_3 or Surface_mesh gives different results

I wanted to save a Nef polyhedron into an OFF file for visualizing it. As written in the CGAL Nef polyhedra user manual (see paragraphs 5.4 and 5.5), a Nef polyhedron can be converted both to a Polyhedron_3 or a Surface_mesh. However, I noticed that…
simonet
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Determining concavities of a non-convex polyhedron

Suppose to have a non-convex 3D polyhedron P, expressed as a mesh. What is the best algorithm for determining the set of all its concavities? A first, maybe trivial, answer I thought could be to compute the convex hull C of the polyhedron P, and…
simonet
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Finding m-linearly independent columns of a matrix on MATLAB

Let us have a linear system Ax<= b. To find a vertex of this polyhedral set we need to choose m linearly independent columns of A and solve the system with the corresponding variables. How can I generate all the m-linearly-independent columns using…
independentvariable
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Parma Polyhedra Library: Vertex Enumeration and Floating-Point Arithmetic

I am using the Parma Polyhedra Library (PPL) to do vertex enumeration of a given polyhedron. This has been discussed here. However, i cannot figure out how to use rational numbers instead of integers in the computation. The code below generates a…
Andreas Orthey
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Are there other finite element types besides the usual?

By finite element type I specifically mean element geometry. I am aware of Quad, Tri, Tet & Hex but are there other types, eg a hexagonal prism, rhombihedral etc..
DrBwts
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Compiler error Parma Polyhedra Library: undefined reference to `Parma_Polyhedra_Library::Init::Init()'

I downloaded last version gmp and ppl from their official websites and installed well. AFAIS, all of library files are in /usr/local/lib. But when I try to compile and run C++ file by including ppl.hh header, I get the error,…
Soner from The Ottoman Empire
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CGAL: Simplify convex polyhedra in 3D

I have been using the cgal library to generate convex hulls which are further used for discrete element simulations. Currently, I am trying to make the polyhedral particles break, which is right now implemented as plane clipping of the polyhedron.…
paffff
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How to determine the points of intersection between a 3d circle and polyhedron in matlab

I have a workspace containing a polyhedral shape so I sliced the workspace into different 3D circles. For each circle, it is either there occurs an intersection with the polyhedral or not. Is it possible to determine if the circle intersects with…
Olatunji
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Algorithm for checking if 3D point inside convex polyhedron (square pyramid)

I am looking robust collision detection algorithms and found an awesome book called Realtime Collision Detection by Christer Ericson. I am trying to use a particular algorithm which checks whether a given point is inside convex polyhedron (in 3D…
rbaleksandar
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Creating a "cup" with polyhedra in openSCAD

I am trying to create a "cup" shape (hollow with one end open) with octagonal prisms (using the polyhedron function). When I render my code, OpenSCAD does not render the bottom and inside faces. What am I doing wrong? Thanks! My Code: difference()…
ZuluDeltaNiner
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when I load .off file in CGAL Polyhedron demo, nothing were showed in the window

enter image description here I have build the demo succesfully, and runs the demo, but when I try to load .off file, it comes out nothing. In the console window, the error message "…
Daniel
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PSLG to polyhedral complex

We have a PSLG whose outer face is a triangle and the other faces could either be a triangle or a quadrilateral. We are given the half-edges to walk through the PSLG. What is an efficient algorithm that requires the least number of changes to…
Burt
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Split hollow sphere based on circumscribed Dodecahedron sides

I'm attempting to print out a 300mm hollow sphere on my Printrbot by shaping the sphere's internal cavity as a regular, circumscribed polyhedron and splitting up the sphere based on the sides of the circumscribed polyhedron. I first attempted this…
kwelliott
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Three.js polygon/polyhedron name or title

Here is a sample code of my page. I want to get name of object, when user clicks it. And it works well with cube or sphere, but fails with polygon. You may watch console logs to see clicks responds. What should I do to get polygon name on…
Somerussian
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Three.js: polyhedron rounded corners (faces)

I've created a polyhedron and it has rounded corners (or even faces - I don't know which explanation is correct). How can I set border-radius? Is it possible to remove rounding and make usual corners? Code is below. …
Somerussian
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