Just released a *faces.scad* that can generate faces for simple polyhedrons: https://github.com/runsun/faces.scad/blob/master/faces.scad. <https://github.com/runsun/faces.scad/blob/master/faces.scad> This is part of a lib that I am working on. During my course of learning polyhedron, the faces is the most frustrating obstacle. So I think that I'd make my face() a stand-alone lib so this might help people like me. This lib currently only supports 5 very basic polyhedrons. And it use 4-point faces. I do hope that, in the future, openscad will consider having a better faces() as the builtin. The function api: > faces( shape // cubesides|rod|chain|ring|tube , nside // # of sides > , nseg // # of segments for chain ) Its currently-supported 5 shapes are demonstrated below. The points, *pts* are given in the example files in the release. The construction of those *pts* is beyond the scope of this work. <http://forum.openscad.org/file/n12809/demo_cubesides.png> &nbsp;&nbsp;cubesides &nbsp;&nbsp;Needed for building other shape faces. > f=faces( "cubesides", nside=4 );polyhedron( points=pts, faces=f ); <http://forum.openscad.org/file/n12809/demo_rod.png> &nbsp;&nbsp;rod &nbsp;&nbsp;Same as a cylinder > polyhedron( points=pts, faces=faces( "rod", nside=4 ));polyhedron( > points=pts , faces=faces( "rod", nside=6 )); <http://forum.openscad.org/file/n12809/demo_tube.png> &nbsp;&nbsp;tube > f=faces( "tube", nside=20 );polyhedron( points= pts , faces=f ); <http://forum.openscad.org/file/n12809/demo_chain.png> &nbsp;&nbsp;chain > f=faces( "chain", nside=4, nseg=5 );polyhedron( points=pts, faces=f ); <http://forum.openscad.org/file/n12809/demo_ring.png> &nbsp;&nbsp;ring &nbsp;&nbsp;A ring is like a closed chain. > f=faces( "ring", nside=4, nseg=10 );polyhedron( points=pts, faces= f ); ----- $ Runsun Pan, PhD $ -- OpenScad_DocTest: doc and unit test ( Github , Thingiverse ) $ -- hash parameter model: here , here $ -- Linux Mint 17.1 Rebecca x64 + OpenSCAD 2015.03.15/2015.04.01.nightly -- View this message in context: http://forum.openscad.org/A-faces-function-for-simple-polyhedrons-tp12809.html Sent from the OpenSCAD mailing list archive at Nabble.com.

Hi runsun, Nice utilities. I downloaded your file faces.scad, and tested it with the latest mac OS X version. The preview work fine, but the rendering fails when trying to render the ring. This happen using showall(); when loading, the console looks like below: Compiling design (CSG Tree generation)... ECHO: "" ECHO: "ring_faces ( "darkslategray" )" ECHO: "cubesides_faces ( "olive" )" ECHO: "rod_faces1 ( "olive" )" ECHO: "rod_faces2 ( "red" )" ECHO: "tube_faces ( "green" )" ECHO: "chain_faces ( "darkcyan" )" ECHO: "" Compiling design (CSG Products generation)... Geometries in cache: 6 Geometry cache size in bytes: 16752 CGAL Polyhedrons in cache: 0 CGAL cache size in bytes: 0 Compiling design (CSG Products normalization)... Normalized CSG tree has 6 elements Compile and preview finished. Total rendering time: 0 hours, 0 minutes, 0 seconds When rendering, I get: Compiling design (CSG Tree generation)... ECHO: "" ECHO: "ring_faces ( "darkslategray" )" ECHO: "cubesides_faces ( "olive" )" ECHO: "rod_faces1 ( "olive" )" ECHO: "rod_faces2 ( "red" )" ECHO: "tube_faces ( "green" )" ECHO: "chain_faces ( "darkcyan" )" ECHO: "" Rendering Polygon Mesh using CGAL... PolySet has nonplanar faces. Attempting alternate construction ERROR: Alternate construction failed. CGAL error in CGAL_Nef_polyhedron3(): CGAL ERROR: assertion violation! Expr: e->incident_sface() != SFace_const_handle() File: /Users/kintel/code/OpenSCAD/openscad/../libraries/install/include/CGAL/Nef_S2/SM_const_decorator.h Line: 326 PolySet has nonplanar faces. Attempting alternate construction PolySet has nonplanar faces. Attempting alternate construction PolySet has nonplanar faces. Attempting alternate construction Geometries in cache: 20 Geometry cache size in bytes: 50256 CGAL Polyhedrons in cache: 2 CGAL cache size in bytes: 616688 Total rendering time: 0 hours, 0 minutes, 0 seconds Top level object is a 3D object: Simple: no Vertices: 132 Halfedges: 734 Edges: 367 Halffacets: 482 Facets: 241 Volumes: 5 WARNING: Object may not be a valid 2-manifold and may need repair! Rendering finished. All the object are rendered except the ring. Regards, Jean-Paul AC9GH > On Jun 6, 2015, at 4:31 AM, runsun <runsun@gmail.com> wrote: > > Just released a faces.scad that can generate faces for simple polyhedrons: > https://github.com/runsun/faces.scad/blob/master/faces.scad. > > This is part of a lib that I am working on. During my course of learning polyhedron, the faces is the most frustrating obstacle. So I think that I'd make my face() a stand-alone lib so this might help people like me. > > This lib currently only supports 5 very basic polyhedrons. And it use 4-point faces. I do hope that, in the future, openscad will consider having a better faces() as the builtin. > > The function api: > faces( shape // cubesides|rod|chain|ring|tube > , nside // # of sides > , nseg // # of segments for chain > ) > > Its currently-supported 5 shapes are demonstrated below. The points, pts are given in the example files in the release. The construction of those pts is beyond the scope of this work. > > > cubesides > > Needed for building other shape faces. > f=faces( "cubesides", nside=4 ); > polyhedron( points=pts, faces=f ); > > > rod > > Same as a cylinder > polyhedron( points=pts, faces=faces( "rod", nside=4 )); > polyhedron( points=pts , faces=faces( "rod", nside=6 )); > > > tube > > f=faces( "tube", nside=20 ); > polyhedron( points= pts , faces=f ); > > > chain > > f=faces( "chain", nside=4, nseg=5 ); > polyhedron( points=pts, faces=f ); > > > ring > > A ring is like a closed chain. > f=faces( "ring", nside=4, nseg=10 ); > polyhedron( points=pts, faces= f ); > > $ Runsun Pan, PhD > $ -- OpenScad_DocTest: doc and unit test ( Github, Thingiverse ) > $ -- hash parameter model: here, here > $ -- Linux Mint 17.1 Rebecca x64 + OpenSCAD 2015.03.15/2015.04.01.nightly > > View this message in context: A faces( ) function for simple polyhedrons > Sent from the OpenSCAD mailing list archive at Nabble.com. > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

I believe the error is trying to render two or more separate objects. Try do this: module showall(){ cubesides_faces("olive"); rod_faces1("olive"); } and it still gives you the same rendering error. Render them one at a time will be ok. ----- $ Runsun Pan, PhD $ -- OpenScad_DocTest: doc and unit test ( Github , Thingiverse ) $ -- hash parameter model: here , here $ -- Linux Mint 17.1 Rebecca x64 + OpenSCAD 2015.03.15/2015.04.01.nightly -- View this message in context: http://forum.openscad.org/A-faces-function-for-simple-polyhedrons-tp12809p12812.html Sent from the OpenSCAD mailing list archive at Nabble.com.

runsun wrote > <br/> > The function api: >> <code style="font-size:13px"> >> <pre> >> faces( shape // cubesides|rod|chain|ring|tube >> , nside // # of sides >> , nseg // # of segments for chain >> ) >> </pre> >> </code> This would be a great way discourage / deprecate the nasty $fs=6 i've seen in models where hexagons are created by degrading the quality of cylinders. imho $fa, $fs and $fn should only be user to control the rendering resolution of quality. Cheers, Ivo -- View this message in context: http://forum.openscad.org/A-faces-function-for-simple-polyhedrons-tp12809p12822.html Sent from the OpenSCAD mailing list archive at Nabble.com.