STL shows unwanted co-planar faces in SketchUp and DesignSpark
When I import the STL file exported from OpenSCAD from the code below into
either SketchUp or DesignSpark all faces of the model have two co-planar
sections.
http://forum.openscad.org/file/n16152/OpenSCAD.png
What's going on?
pitch = 1.25; //8mm coarse thread
height = pitch * cos(30); //based on 60 degree profile
major_diameter = 7.78; //M8 = 7.78-8.00
minor_diameter = major_diameter - 2*(height*5/8);
echo ("major_diameter = ", major_diameter);
echo ("minor_diameter = ", minor_diameter);
echo ("pitch = ", pitch);
echo ("height = ", height);
//external thread for a bolt
square_size = pitch/8+.2;
linear_extrude(height = .01)
difference()
{
polygon(points = [ [0, 0], [0, pitch],[height,pitch/2], ], convexity =
2);
#translate([height*7/8+square_size/2,pitch/2,0])
square(square_size,center=true);
}
--
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STL files only store triangles so each face is broken into triangular
facets.
On 15 February 2016 at 19:04, psehorne Paul@sehorne.org wrote:
When I import the STL file exported from OpenSCAD from the code below into
either SketchUp or DesignSpark all faces of the model have two co-planar
sections.
http://forum.openscad.org/file/n16152/OpenSCAD.png
What's going on?
pitch = 1.25; //8mm coarse thread
height = pitch * cos(30); //based on 60 degree profile
major_diameter = 7.78; //M8 = 7.78-8.00
minor_diameter = major_diameter - 2*(height*5/8);
echo ("major_diameter = ", major_diameter);
echo ("minor_diameter = ", minor_diameter);
echo ("pitch = ", pitch);
echo ("height = ", height);
//external thread for a bolt
square_size = pitch/8+.2;
linear_extrude(height = .01)
difference()
{
polygon(points = [ [0, 0], [0, pitch],[height,pitch/2], ], convexity =
2);
#translate([height*7/8+square_size/2,pitch/2,0])
square(square_size,center=true);
}
--
View this message in context:
http://forum.openscad.org/STL-shows-unwanted-co-planar-faces-in-SketchUp-and-DesignSpark-tp16152.html
Sent from the OpenSCAD mailing list archive at Nabble.com.
OpenSCAD mailing list
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Darn! but THANKS, nophead. I'll have to work around that behavior.
--
View this message in context: http://forum.openscad.org/STL-shows-unwanted-co-planar-faces-in-SketchUp-and-DesignSpark-tp16152p16154.html
Sent from the OpenSCAD mailing list archive at Nabble.com.
On Feb 15, 2016, at 14:23 PM, psehorne Paul@Sehorne.org wrote:
Darn! but THANKS, nophead. I'll have to work around that behavior.
What formats do DesignSpark and SketchUp import which would be able to provide the wanted results?
Merging planar triangles into larger faces is something that can be done on import. Such functionality would typically be part of said CAD packages. I would recommend contacting customer support there and inquire about this.
-Marius
Meshmixer is a free program that has an "inspector" feature. I've not intentionally created co-planar triangles, so I can't say that it would correct it, but the price is right.
On Wednesday, February 17, 2016 4:52 PM, Marius Kintel <marius@kintel.net> wrote:
On Feb 15, 2016, at 14:23 PM, psehorne Paul@Sehorne.org wrote:
Darn! but THANKS, nophead. I'll have to work around that behavior.
What formats do DesignSpark and SketchUp import which would be able to provide the wanted results?
Merging planar triangles into larger faces is something that can be done on import. Such functionality would typically be part of said CAD packages. I would recommend contacting customer support there and inquire about this.
-Marius
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Can someone point me to an authoritative STANDARD for .stl files that says that all facets must consist of a single outerloop and that loop must contain exactly 3 vertices?
This is, of course, for ASCII .stl files.
--
Kenneth Sloan
KennethRSloan@gmail.com
Vision is the art of seeing what is invisible to others.
On Feb 17, 2016, at 15:51 , Marius Kintel marius@kintel.net wrote:
On Feb 15, 2016, at 14:23 PM, psehorne Paul@Sehorne.org wrote:
Darn! but THANKS, nophead. I'll have to work around that behavior.
What formats do DesignSpark and SketchUp import which would be able to provide the wanted results?
Merging planar triangles into larger faces is something that can be done on import. Such functionality would typically be part of said CAD packages. I would recommend contacting customer support there and inquire about this.
-Marius
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
On Feb 17, 2016, at 18:46 PM, Kenneth Sloan kennethrsloan@gmail.com wrote:
Can someone point me to an authoritative STANDARD for .stl files that says that all facets must consist of a single outerloop and that loop must contain exactly 3 vertices?
AFAIK, there is no authorative STL standard.
Technically, you could store any size polygon in STL files, but the convention is that it’s only used for triangles.
As binary STL doesn’t even have an option for storing other than triangles, that should be a good guideline for what to put in ASCII STL files, to allow bi-directional compatibility.
-Marius
Here is the original document I think:
https://static-content.springer.com/lookinside/chp%3A10.1007%2F978-1-4419-1120-9_13/001.png
It says an STL file consists of lists of triangular facets.
On 17 February 2016 at 23:46, Kenneth Sloan kennethrsloan@gmail.com wrote:
Can someone point me to an authoritative STANDARD for .stl files that says
that all facets must consist of a single outerloop and that loop must
contain exactly 3 vertices?
This is, of course, for ASCII .stl files.
--
Kenneth Sloan
KennethRSloan@gmail.com
Vision is the art of seeing what is invisible to others.
On Feb 17, 2016, at 15:51 , Marius Kintel marius@kintel.net wrote:
On Feb 15, 2016, at 14:23 PM, psehorne Paul@Sehorne.org wrote:
Darn! but THANKS, nophead. I'll have to work around that behavior.
What formats do DesignSpark and SketchUp import which would be able to
provide the wanted results?
Merging planar triangles into larger faces is something that can be done
on import. Such functionality would typically be part of said CAD packages.
I would recommend contacting customer support there and inquire about this.
-Marius
OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
an authoritative STANDARD for .stl files
Wikipedia probably isn't authoritative:
The STL file format appears capable of defining a polyhedron
with any polygonal facet, but in practice it is only ever used
for triangles, which means that much of the syntax of the
ASCII protocol is superfluous.
So, yeah, you /could/ put more than three vertexes in each entry, but
/everything/ else would immediately break.
They reference a "Standard Data Format for Fabbers" document dating back
to 1989 that everybody probably used as The Definitive Document:
http://www.fabbers.com/tech/STL_Format
It starts off by saying that it's triangles all the way down...
--
Ed
softsolder.com
This is a historical reconstruction of the original 1989 STL specification.
http://www.fabbers.com/tech/STL_Format
On Wednesday, 17 February 2016, Kenneth Sloan kennethrsloan@gmail.com
wrote:
Can someone point me to an authoritative STANDARD for .stl files that says
that all facets must consist of a single outerloop and that loop must
contain exactly 3 vertices?
This is, of course, for ASCII .stl files.
--
Kenneth Sloan
KennethRSloan@gmail.com javascript:;
Vision is the art of seeing what is invisible to others.
On Feb 17, 2016, at 15:51 , Marius Kintel <marius@kintel.net
javascript:;> wrote:
On Feb 15, 2016, at 14:23 PM, psehorne Paul@Sehorne.org wrote:
Darn! but THANKS, nophead. I'll have to work around that behavior.
What formats do DesignSpark and SketchUp import which would be able to
provide the wanted results?
Merging planar triangles into larger faces is something that can be done
on import. Such functionality would typically be part of said CAD packages.
I would recommend contacting customer support there and inquire about this.
-Marius
OpenSCAD mailing list
Discuss@lists.openscad.org javascript:;
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org