Autoknit

A re-implementation of "Automatic Machine Knitting of 3D Meshes". Does not match the code used in the paper exactly, but is close in most regards.

The latest version of this code is available at https://github.com/textiles-lab/autoknit .

License

This code is placed in the public domain.

Pre-Built Releases

This code is automatically built using Github Actions; check for releases at https://github.com/textiles-lab/autoknit/releases . However, it is also reasonably straightforward to build on your own using the steps below.

Building

Building autoknit is handled with the single-file build tool maek, and uses the nest-libs pre-built library package (for SDL2 and glm), along with the Eigen linear algebra library, which you will need to fetch separately.

MacOS setup

#install nodejs (used for build script and to post-process scheduled output):
brew install node

#extract nest-libs package as a sibling of autoknit folder:
curl 'https://github.com/15-466/nest-libs/releases/download/v0.13/nest-libs-macos-v0.13.tar.gz' -L -O
tar xvfz nest-libs-macos-v0.13.tar.gz

#clone repository:
git clone git@github.com:textiles-lab/autoknit
cd autoknit
git submodule init
git submodule update

Linux setup

#install nodejs (used for build script and to post-process scheduled output):
sudo apt-get install nodejs

#extract nest-libs package as a sibling of autoknit folder:
curl 'https://github.com/15-466/nest-libs/releases/download/v0.13/nest-libs-linux-v0.13.tar.gz' -L -O
tar xvfz nest-libs-macos-v0.13.tar.gz

#clone repository:
git clone git@github.com:textiles-lab/autoknit
cd autoknit
git submodule init
git submodule update

Windows setup

First, make sure that git is installed in such a way that it can be run from a command prompt; also install nodejs, which is used by the build script and to post-process scheduled output.

Then, from a Visual Studio 2022 > x64 Native Tools Command Prompt for VS 2022 command prompt do:

#clone repository:
git clone git@github.com:textiles-lab/autoknit
cd autoknit
git submodule init
git submodule update

Finally, download the nest-libs package (https://github.com/15-466/nest-libs/releases/download/v0.13/nest-libs-windows-v0.13.zip) and place the contained nest-libs/ folder next to the autoknit folder where you checked out the code.

Linux/Windows/MacOS build

NOTE: on windows, be sure to use a Visual Studio 2022 > x64 Native Tools Command Prompt for VS 2022.

cd autoknit
node Maekfile.js

Command line flags for maek include:

• -j8 run with 8 compilation jobs in parallel. Adjust the number to suit your machine. Defaults to number of cores + 1.
• -q quit on first error
• Specifically, node Maekfile.js -j1 -q is useful when you want to work on one error at a time during development!

Note that maek is a small build system, entirely contained in Maekfile.js. You can read the file to see more about command line options or to see how the build is structured.

Usage

Step-by-step instructions for creating knitting machine instructions for the misc-cactus.obj model from the autoknit-tests repository.

Step 1: Constraints

Launch the interface, telling it to load from misc-cactus.obj and to save constraints to misc-cactus.cons:

cd dist
./interface obj:misc-cactus.obj constraints:misc-cactus.cons

(Note that the interface executable is built in the dist/ subdirectory, so you will need to change to that directory before running it.)

You will see a 3D view of the loaded model:

You can rotate this model with the right mouse button, zoom with the mouse wheel, and pan with shift + right mouse button.

The point on the surface your mouse is over will be highlighted with a grey sphere (the red, green, and blue spheres show the location of the corners of the triangle:

Pressing the c key will add a constraint:

Pressing the c key while hovering over a constraint will add a connected constraint point, which you can press left mouse button to place:

You can click and drag constraint points to move them:

Pressing the + key while hovering over a constraint will move it later in time (redder) while pressing the - key will move it earlier in time (bluer):

Pressing the X key while hovering over a constraint will delete it:

Before you can proceed to the next step, you will need to create constraints for (at least) all of the boundaries of the cactus:

You can also place constraints elsewhere on the model to control the knitting direction, and use the R key to cut out a region around a constraint (useful for starting/ending on meshes without boundaries).

Step 2: Peeling/Linking

Now that constraints are specified, the rest of the steps proceed automatically. However, the interface can provide visualization tools to show you what is happening.

Manual method:

Load the cactus object and the constraints into the interface. The obj-scale parameter tells the interface how much to scale the object, while the stitch-width and stitch-height parameters give the stitch size relative to the scaled object. The save-traced: parameter tells the interface where to save its traced stitches.

./interface obj:misc-cactus.obj load-constraints:misc-cactus.cons obj-scale:10.0 stitch-width:3.66 stitch-height:1.73 save-traced:misc-cactus.st

Press the p key to step through peeling:

During peeling, you can use the g key to show or hide the portions of the row-column graph created so far, and the s key to toggle whether the original model, interpolated value, or current slice model are being shown:

Once the peeling has finished, you can press t to create and save the traced path:

Automatic method:

If you don't want to press p a whole lot, you can just pass the peel-step:N option to do N steps of peeling. peel-step:-1 will peel until the mesh is finished.

./interface obj:misc-cactus.obj load-constraints:misc-cactus.cons obj-scale:10.0 stitch-width:3.66 stitch-height:1.73 save-traced:misc-cactus.st peel-step:-1

Step 3: Scheduling

Now that the traced stitches have been created, they need to be assigned knitting machine needles. We call this step scheduling, and it has its own executable, called schedule. The only parameters used by schedule are st: which gives an input stitches file and js: which gives an output javascript file:

./schedule st:misc-cactus.st js:misc-cactus.js

Schedule doesn't have an UI; it just does a relatively large combinatorial search and then dumps its output into a javascript file.

Step 4: Knitout

Running the javascript file created by schedule will create knitout instructions, ready for use on your machine:

NODE_PATH=.. node misc-cactus.js out:misc-cactus.k

Note that the javascript file created by schedule uses some helper functions defined in the node_modules/autoknit.js file to do things like cast on tubes, bring in/out yarns, and perform transfers. You may want to customize autoknit.js for your machine.

Status By Pipeline Step

This implementation is mostly complete, but is not fully working.

• Interface/wrapper - working.
• Model (obj) loading - working.
• Constraint specification - working.
• Peeling - mostly working.
  • Could be improved to handle ending with short rows.
  • Could be improved to deal with orphaned chains.
• Linking (including split/merge cases) - working.
• Tracing - mostly working.
  • Could be improved with more extensive ancestor traversal when tucking at the ends of short rows.
  • Sometimes generates short yarns; next-stitch-picking heuristic could be improved.
  • Might want to add a lazy vs eager switch for moving to the next row after splits. (Currently, the behavior is eager).
• Scheduling - working for small cases only.
  • Need to add a greedy version (currently only optimal is used).
• Knitting instructions -- mostly working.
  • Need a better yarn-in function for split tubes that tucks on front/back and then drops later.
  • Should add the option to use separate yarn for starting tubes
  • Should add the option to tuck yarn in from the edge of the beds