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

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.

PreviewAttachmentSize
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 ...

PreviewAttachmentSize
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.

PreviewAttachmentSize
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,...