I have many stl CAD files for 3D printing and I was wondering how I can manipulate an individual CAD file by making a simple change programatically. Like if I want to double the dimensions of everything in the CAD file, how could I accomplish this in python? I could convert it to gcode if that makes things simpler.
I have come across FreeCad but I am not sure if this is the easiest and best way of programmatically altering CAD files. I also wanted an option that allows for freedom of manipulation beyond just size, maybe also seeing how I can programmatically alter the shape of the CAD file.
Well to be precise, STL files are even not meshes, but triangles soups. Which means that triangles are even not connected to each other (well they need to be adjacent to be used by software generatif g-code, but no obligation else)
just for clarification: g-code format is just a sequence of instructions for the machines (3d-printers, etc) so it's very good for printers, but also certainly the worst format to manipulate geometry.
one solution
you can use the python pymadcad module to deal with STL files
So for simple transformation operations (such as scale, translation etc)
from madcad import *
part = read('path/to/your_file.stl')
transformed = part.transform(mat3(2)) # scale by a factor 2 (diagonal matrix of 2)
write(transformed, 'path/to/output_file.stl')
If you need more complex operations (such as booleans, chamfers, etc) you will need to make the triangle connected again before the desired operations.
from madcad import *
part = read('path/to/your_file.stl')
part.mergeclose() # merge points at the same location
# your desired operations (example)
transformed = union(part, icosphere(vec3(1,1,1), 3.)) # add a sphere a diameter 3
write(transformed, 'path/to/output_file.stl')
note
pymadcad is internally using numpy-stl to import stl files, if you need only basic manipulations you can also only install that one
STL files are meshes. Their exterior is defined by triangulated surfaces. Meshes are notoriously difficult to modify after the fact. That's why you always want to save your designs in the native format and also in an open solid format like .STP or .IGES.
That said, simple scaling of a mesh is pretty easy and can be done trivially in FreeCAD.
You can do it in the gui in the mesh design workbench or through python. Here's a post about that:
https://forum.freecadweb.org/viewtopic.php?t=9109#p74047
FreeCAD also has some tools to convert a mesh into a solid. Results are usually less than spectacular but might be good enough depending on your needs. Search on the FreeCAD forum for posts about converting or look here: https://wiki.freecadweb.org/FreeCAD_and_Mesh_Import
Gcode doesn't say anything about the model itself. It specifies where a tool should move so it's just a series of directives that move a tool from place to place at a given speed. Going from Gcode to a model that you can edit is pretty difficult or impossible.
Related
I am trying to transform a solid created in a CAD program (saved in a STEP file) into a CSG object constructed with simple primitives.
I am not very familiar with the different geometry file formats but as far as I understand it should be possible to do, at least with some simple solids, since the information about the face shapes etc. is stored in a STEP file. I have found this issue https://github.com/tpaviot/pythonocc-core/issues/470 which proves you can extract some of this information. However I am not sure this is enough to achieve my goal.
As an example, I would like to go from the following CAD design / STEP file:
to a CSG description which should describe the geometry as a big cylinder with three smaller cylinders as subtractions.
Ideally I would use a python library for this purpose, perhaps this library is a good candidate.
However I am afraid this isn't theoretically possible since I am not finding much information online.
As a last resort I could just mesh the solid and generate a CSG description using a tessellated solid, but I want to use simple primitives such as boxes or cylinders whenever possible.
I would love to know if this is possible to do and if so, I would love some resources to read about this. Thanks!
Currently, I use MATLAB extensively for analyzing experimental scientific data (mostly time traces and images). However, again and again I keep running into fundamental problems with the MATLAB language and I would like to make the switch to python. One feature of matlab is holding me back however: its ability to add datatips to plots and images.
For a line plot the datatip is a window next to one of the data points that shows its coordinates. This is very useful to quickly see where datapoints are and what their value is. Of course this can also be done by inspecting the vectors that were used to plot the line, but that is slightly more cumbersome and becomes a headache when trying to analyze loads of data. E.g. let's say we quickly want to know for what value of x, y=0.6. Moving the datatip around will give a rough estimate very quickly.
For images, the datatip shows the x and y coordinates, but also the greyscale value (called index by MATLAB) and the RGB color. I'm mainly interested in the greyscale value here. Suppose we want to know the coordinates of the bottom tip of the pupil of the cat's eye. A datatip allows to simply click that point and copy the coordinates (either manually or programmatically). Alternatively, one would have to write some image processing script to find this pixel location. For a one time analysis that is not worthwhile.
The plotting library for python that I'm most familiar with and that is commonly called the most flexible is matplotlib. An old stock overflow question seems to indicate that this can be done using mpldatacursor and another module seems to be mplcursors. These libraries do not seem to be compatible with Spyder, however, limiting their usability. Also, I imagine many python programmers would be using a feature like datatips, so it seems odd to have to rely on a 3rd party module.
Now on to the actual question: Is there any module (or simple piece of code that I could put in my personal library) to get the equivalent of MATLAB's datatips in all figures generated by a python script?
Currently I'm developing a library to manage some stream of data, but at some point I'd like to represent my findings on 3d. I would like to develop a 3D view of my project:
I have:
- All the 3D vertices of one single block
- All the properties related with the object
The question is: Can I do this on python? Which library should I use? Is there any other solution rather than
Depending on what kind of display you are looking for.
if you need to display it as scientific data, there is VTK which propose a great variety of ways to display
if you want to operate your 3d data, display and inspect it at the same time, you can go for pymadcad (a lot of other modules are available for mesh manipulation only, but without display)
if you want a highly flexible rendering pipeline, you can take a look at moderngl, which is very close to the hardware reality by makes everything extremely simple
if you want a high interaction and flexibility in displaying meshes, maybe a game engine, like Panda3D can be more convenient
I work with a huge library of components (step files) that are currently used in various products. My goal is to identify parts with great similarity in order to unify them. At the moment I can think of two solutions:
Compare certain properties of the 3D data with a suitable python library. E.g. identify parts with similar volume and dimensions.
Convert step files to JPG and compare the images with one of the many image processing libraries.
Both have their pitfalls.
Is there a library that can handle step files or do you know a better way to solve the problem?
You are underestimating the complexity of this project. Once the STEP geometry is loaded, taking dimensions on it (apart from bounding box extents) can be really cumbersome. Very different parts can have the same volume and comparing bitmaps you completely ignore the hidden part of the geometry.
What I want is to create some electrical symbols (transistor, capacitor, diode...) and than to use them like a puzzle elements to create electrical scheme drawing and save it as one SVG file.
My idea is
Use some kind of scheme for SVG (like XML Scheme) to create complex electrical symbols out of basic shapes: lines, circles, square...
Use instances of those symbols, with coordinates (which I load in Python) to put them in the right place in final electrical scheme
Save it as .SVG
What is the best way to do that? (SVGFig looks like it would do it, but I can't find similar examples)
Examples would be appreciated.
Hm, not sure if it helps you, but there was a program, called Dia diagram editor, meant for drawing SVGs and equipped with Python command line. It's quite glitchy, though, but at least it has a good set of electrical symbols within and works with SVG. Good luck!
Here are some examples:
https://mail.gnome.org/archives/dia-list/2010-August/msg00014.html
https://live.gnome.org/Dia/Python