The following OpenSCAD program doesn't work. It should produce a tetrahedron (not regular).
I set convexity to be larger than 1, but that doesn't seem to help. // Testing OpenSCAD version 2013.06 intersection() { multmatrix([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 1]]) polyhedron(points = [[100, 0, 0], [50, 86.6025, 0], [50, 86.6025, 0]], triangles = [[0, 1, 2]], convexity = 5); multmatrix([[1, 0, 0, 0], [0, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 1]]) polyhedron(points = [[100, 0, 0], [50, 86.6025, 0], [50, 86.6025, 0]], triangles = [[0, 1, 2]], convexity = 5); multmatrix([[0, 0, 1, 0], [0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1]]) polyhedron(points = [[100, 0, 0], [50, 86.6025, 0], [50, 86.6025, 0]], triangles = [[0, 1, 2]], convexity = 5); multmatrix([[0.788675, 0.211325, 0.57735, 10], [0.211325, 0.788675, 0.57735, 10], [0.57735, 0.57735, 0.57735, 10], [0, 0, 0, 1]]) polyhedron(points = [[100, 0, 0], [50, 86.6025, 0], [50, 86.6025, 0]], triangles = [[0, 1, 2]], convexity = 5); } _______________________________________________ OpenSCAD mailing list [hidden email] http://rocklinux.net/mailman/listinfo/openscad http://openscad.org  https://flattr.com/thing/121566 
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On 20130627, at 10:16 , Henry Baker wrote:
> The following OpenSCAD program doesn't work. It should produce a tetrahedron (not regular). > You can only intersect solids, and your polyhedrons are planar. You cannot use OpenSCAD to build a volume from intersecting planes. You could build 2D polygons, linear_extrude them and rotate them in place, then do the intersection and you might get what you're looking for. Marius _______________________________________________ OpenSCAD mailing list [hidden email] http://rocklinux.net/mailman/listinfo/openscad http://openscad.org  https://flattr.com/thing/121566 
In reply to this post by Henry Baker
I'm trying to intersect 3 cubes, but for some reason, OpenSCAD seems to ignore the first cube in the following intersection.
The result should be a cube entirely in the 1st octant. The intersection of cubes 2 & 3 works fine, but the intersection with cube 1 doesn't work. // Test OpenSCAD version 2013.06 intersection() { multmatrix([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 1]]) multmatrix([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 50], [0, 0, 0, 1]]) cube(size = [100, 100, 100], center = true); multmatrix([[1, 0, 0, 0], [0, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 1]]) multmatrix([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 50], [0, 0, 0, 1]]) cube(size = [100, 100, 100], center = true); multmatrix([[0, 0, 1, 0], [0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1]]) multmatrix([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 50], [0, 0, 0, 1]]) cube(size = [100, 100, 100], center = true); } _______________________________________________ OpenSCAD mailing list [hidden email] http://rocklinux.net/mailman/listinfo/openscad http://openscad.org  https://flattr.com/thing/121566 
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On 20130627, at 11:36 , Henry Baker wrote:
> I'm trying to intersect 3 cubes, but for some reason, OpenSCAD seems to ignore the first cube in the following intersection. > > The result should be a cube entirely in the 1st octant. > > The intersection of cubes 2 & 3 works fine, but the intersection with cube 1 doesn't work. > Works in OpenCSG mode, but not ing CGAL mode  definitely looks like a bug.. Same behavior in all previous versions of OpenSCAD Marius _______________________________________________ OpenSCAD mailing list [hidden email] http://rocklinux.net/mailman/listinfo/openscad http://openscad.org  https://flattr.com/thing/121566 
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