Add boundary for all Primitive geometries

[juliohm]

Given a primitive geometry, we should be able to construct its boundary mesh (or geometry). For example, the boundary of a Ball is a Sphere. The boundary of a Cylinder is a SimpleMesh with two disks and the wall of the cylinder. We can already sample these geometries using our sampling methods, we just need to connect the dots to return a mesh.

• Box
• Ball
• Sphere
• Line
• Ray
• Plane
• Cylinder
• BezierCurve

[HaoxuanGuo]

So, what is the method name? Use the SimpleMesh construction method? As we know, some geometry has many different represent of mesh. For example, sphere has UV sphere, ico sphere, quad sphere and Goldberg polyhedra. How to choose that?

[juliohm]

In the case of Ball the boundary is a Sphere primitive. In the case of other primitives we can use a SimpleMesh.

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On Fri, Nov 19, 2021, 07:47 Haoxuan Guo ***@***.***> wrote: So, what is the method name? Use the SimpleMesh construction method? As we know, some geometry has many different represent of mesh. For example, sphere has UV sphere, ico sphere, quad sphere and Goldberg polyhedra. How to choose that? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#210 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAZQW3ONDHKH4GFZVWY6ZZ3UMYTLVANCNFSM5IECZDPQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[HaoxuanGuo]

@juliohm For Cylinder the number of faces of the wall (Or the number of the edges of the disks) is not exactly as well. In another word, we may require some other parameters to generate the boundary. What about using a kw args?

[juliohm]

Sounds like a good idea. I would create a separate PR for each primitive so that we can more easily assess the design differences.

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On Fri, Nov 19, 2021, 08:05 Haoxuan Guo ***@***.***> wrote: @juliohm <https://github.com/juliohm> For Cylinder the number of faces of the wall (Or the number of the edges of the disks) is not exactly as well. In another word, we may require some other parameters to generate the boundary. What about using a kw args? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#210 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAZQW3L57QFFFVEZWHJH7QLUMYVPZANCNFSM5IECZDPQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[juliohm]

I've implemented a couple of different discretization methods. Now we can discretize the sphere with quadrangles + triangles using any sampling size:

sphere = Sphere((0.,0.,0.), 1.)

mesh = discretize(sphere, RegularDiscretization(100))

viz(mesh, showfacets = true)

and we can pass this polygonal mesh to triangulate to create a triangle mesh:

tmesh = triangulate(mesh)

viz(tmesh, showfacets = true)

I will polish the Makie recipes now to hide these internals so that end users can simply viz(sphere).

[HaoxuanGuo]

Line and Ray has a infinite volume. Are these boundary exist?

[juliohm]

For line we should return `nothing` and for Ray the origin point. Makes sense? That is how the Makie recipes will figure out if there is something to plot.

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On Sat, Dec 4, 2021, 09:29 Haoxuan Guo ***@***.***> wrote: Line and Ray has a infinite volume. Are these boundary exist? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#210 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAZQW3LPQ4ALOABBLERLZBLUPICR3ANCNFSM5IECZDPQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[HaoxuanGuo]

@juliohm Sounds great.

[juliohm]

Ok, just registered a patch release where the following works:

viz(sphere, color = :orange)

[juliohm]

Now we are only missing the boundary of Cylinder which is a cylindrical surface plus two disks and the boundary of BezierCurve. In the first case we need a new struct to represent the cylindrical surface, like we do with Ball -> Sphere. In the last case we can return the two end points as a PointSet.

Let me know if you want to work on that @HaoxuanGuo 👍🏽

[HaoxuanGuo]

@juliohm I am not familiar on the topologic of mesh. But I would like to have a try.

[juliohm]

@HaoxuanGuo I will work on the cylinder case now, it should be ready by the end of the day. If you can help with the BezierCurve to add a boundary and maybe review the recipe in MeshViz.jl that would be great.

[juliohm]

Now all primitives have boundary. I did refactor the solid Cylinder type and also introduced a new CylinderSurface type. We need to review these primitives in the future and try to use more constructive geometry to avoid code repetition.