how to make a basic prism

riviera's picture

Hello, can someone please help me understand/show an example of how to make a basic 3d - prism / pyramid!? thx

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riviera's picture
Re: how to make a basic prism

I guess with Kineme GL Triangles!?...any help with vertex positions? - wrapped in render in image, then lighting patch,....seems longish work around for a fairly 'primitive' shape!?

liik's picture
Re: how to make a basic prism

...best probable way is to import a 3D model from a modeling software in any of the QC supported formats: Kineme3D or .dae... ... A not so good but quick way is to use the Cylinder patch and reduce the Number Of Slices and Number Of Stacks in the Inspector Settings panel (Cmd+2). This is not good because something weird happens when you reduce the Number Of Slices to 3 because the triangle base of the Cylinder doesn't match the vertices of the sides...if you use 4 or more it's fine.

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prism_tetra_pyramid.qtz4.26 KB

riviera's picture
Re: how to make a basic prism - Tetrahedron

Thank you Liik for your suggestions and example,...I was really hoping to make a 4 sided equilateral prism - a 'tetrahedron',....I don't have any 3d modeling software - have had a look at 'Blender'(seems very confusing to me),.... I've also had a look around the web for a mesh - to no avail...

I'm feeling a bit dismayed that this is not a simple task,... - weird indeed, that the cylinder option doesn't like 3 slices.

perhaps I need to start learning some scripting,...

ps i really like your 'tetra screen'

A tetrahedron is a beautiful shape - anyone else up for the challenge? ;-)

cwright's picture
Re: how to make a basic prism

liik wrote:
This is not good because something weird happens when you reduce the Number Of Slices to 3 because the triangle base of the Cylinder doesn't match the vertices of the sides...if you use 4 or more it's fine.

Actually (having looked at that bug before ;) -- it's any odd number of slices -- it's just most apparent with 3, but it happens with 5, 7, 9, ... 2*n+1.

liik's picture
Re: how to make a basic prism - Tetrahedron

...blender is an awesome and advanced modeling, tool. For simple stuff try http://www.wings3d.com/, and for conversion between formats someone once suggested http://meshlab.sourceforge.net/ and i found that very useful. ... so all of the odd number sided base polygons are mismatched...how nice. ... here are some different format tetrahedrons for starters ...

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tetraHs.zip12 KB

riviera's picture
basic prism - Interactive polyhedra

ahh,.. hello mr.cwright - was hoping this would get your attention,...

I'd love to see a collection of patches in QC that can help me/us make/play with 'Interactive polyhedra' eg: http://ibiblio.org/e-notes/3Dapp/Convex.htm

starting with the tetrahedron!? ;-)

riviera's picture
Re: how to make a basic prism - Tetrahedron

thanks again Iiik - very helpful,...my backgound is in film/video - and I'm obviously a real QC and 3D noob! - wow I love Kineme :-) - lots to work/play with now. - but wouldn't it be cool to have the all the Platonic solids as Kineme patches!?..

gtoledo3's picture
Re: how to make a basic prism - Tetrahedron

I'm the looky loo that suggested mesh lab, but I also suggest it for modeling, and it's auto smooth is excellent. The interface is simplistic, but for some things, it makes work really quick. The filters and z painting tool are insanely straightforward, useful, and ultra stable. Between that, Sketchup basic with available extra plugins and ruby scripts, and Blender, it's a heck of a free system.

cybero's picture
Re: how to make a basic prism

Find attached a simple tetrahedron, 4 faces, 4 vertices.

Hope that helps.

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tetrahedron.dae_.zip912 bytes

cybero's picture
Re: how to make a basic prism - Tetrahedron

Get Mesh Lab and be sans 3D .dae capable software never again - Open Source and F.O.C [everyone's favourite price].

riviera's picture
Re: how to make a basic prism

thanks Cybero -exactly what I was looking for! :-)

riviera's picture
Re: how to make a basic prism - Tetrahedron

thanks George! - I'm on to it,...