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Auto Layout Feature

marena_richardsonmarena_richardson Member Posts: 20 EDU

I am another member of the team of five college students, mentioned by Jacob Kingery, who got the chance to work with FeatureScript this school year, and this is one of the features we made. Let us know what you think!

Auto Layout is a Feature we built to lay out parts for laser cutting or other manufacturing processes. Auto Layout finds all parts that match a material thickness inputted by the user and lays them out on cut sheets of a specified width and height with a specified spacing between them using a binary tree bin-packing algorithm right in their original Part Studio. All the input parameters have default values that are set in the config file and that can be modified for maximum ease of use. The algorithm approximates parts as rectangles, and places them in order from largest to smallest onto a cut sheet. Each time a part is placed, the remaining space on the cut sheet is split into a portion above and a portion to the right. The algorithm then tries to place the next part on the top sub-sheet and the right sub-sheet, and the algorithm continues splitting and placing in this manner recursively. With this Feature, anyone can design something fully assembled and easily lay its parts out without needing to create additional Assemblies, Drawings, or Part Studios. Its uses extend beyond laser cutting and one of the clients we worked with used it to lay out desk parts that he was cutting out of a sheet of plywood. The Feature can be viewed here: 


The Feature dialog:


An example of Auto Layout being used to lay out desk parts:


Auto Layout Code:

FeatureScript 275;
import(path : "onshape/std/geometry.fs", version : "275.0");
import(path : "b2e35aca6e9ed7a858fa702f", version : "b85c432998567d427f0c5fdb");
annotation { "Feature Type Name": "Auto Layout" }
export const autolayout = defineFeature(function(context is Context, id is Id, definition is map)
       annotation { "Name" : "Thickness of material" }
       isLength(definition.thickness, DEFAULT_THICKNESS);
       annotation { "Name" : "Cut sheet width" }
       isLength(definition.width, DEFAULT_SHEET_WIDTH);
       annotation { "Name" : "Cut sheet height" }
       isLength(definition.height, DEFAULT_SHEET_HEIGHT);
       annotation { "Name" : "Spacing" }
       isLength(definition.spacing, DEFAULT_SPACING);
       annotation { "Name" : "Show Cut Sheet Sketches" }
       definition.showSheets is boolean;
       //step 1 - query for all bodies
       //step 2 - find all the planar faces owned by each body
       //step 3 - sort planar faces by size
       //step 4 - use largest planar face to create a bounding box and check
       //         that the depth of the part = the thickness of the material
       //step 6 - If the part has correct thickness, lie flat on the top plane
       //step 7 - space parts out using a binary tree bin packing algorithm
       // Query for all bodies
       var bodies = evaluateQuery(context, qBodyType(qEverything(EntityType.BODY), BodyType.SOLID));
       // Initialize list of parameters necessary for bin packing
       var blocks = [];
       // Initialize list of bodies that are laser cuttable
       var yesParts = [];
       // Iterate through bodies
       for (var i = 0; i < size(bodies); i += 1)
           // Query for planar faces and sort them by their surface area
           var faces = evaluateQuery(context, qGeometry(qOwnedByBody(bodies[i], EntityType.FACE), GeometryType.PLANE));
           var sorted = sort(faces, function(face1, face2) {
               return evArea(context, {"entities": face2}) - evArea(context, {"entities": face1});
           // Check if part has planar faces (is planar)
           if (size(sorted) > 0) {
               var largestFacePlane = evPlane(context, {
                   "face": sorted[0]
               const orientedCSys = planeToCSys(largestFacePlane);
               const boundingBox is Box3d = evBox3d(context, {
                   "topology": bodies[i],
                   "cSys": orientedCSys
               const deltaX = abs(boundingBox.maxCorner[0] - boundingBox.minCorner[0]);
               const deltaY = abs(boundingBox.maxCorner[1] - boundingBox.minCorner[1]);
               const deltaZ = abs(boundingBox.maxCorner[2] - boundingBox.minCorner[2]);
               // Check that the part has a z depth equal to the thickness of the material
               if (tolerantEquals(definition.thickness, deltaZ)) {
                   blocks = append(blocks, new box({'w': deltaX, 'h': deltaY, 'owner': bodies[i], 'rotated': false}));
                   yesParts = append(yesParts, bodies[i]);
                   // Move parts to the top plane and to the origin
                   var transformFromWorld = fromWorld(orientedCSys);
                   var transformToOrigin = transform(-boundingBox.minCorner);
                   opTransform(context, id + ("transform_to_top_and_origin" ~ i), {
                       "bodies": bodies[i],
                       "transform": transformToOrigin * transformFromWorld
       // Move non laser cuttable parts out of the way
       var noParts = evaluateQuery(context, qSubtraction(qBodyType(qEverything(EntityType.BODY), BodyType.SOLID), qUnion(yesParts)));
       for (var i = 0; i < size(noParts); i += 1) {
           const boundingBox is Box3d = evBox3d(context, {
               "topology": noParts[i]
           var transformToOrigin = transform(-boundingBox.maxCorner);
           var transformAway = transform(vector(-(definition.width * 0.3), 0*meter, 0*meter));
           opTransform(context, id + ("transform_to_origin2" ~ i), {
               "bodies": noParts[i],
               "transform": transformAway * transformToOrigin
       // Everything below this point is for spacing
       var sortedBlocks = sortBlocks(blocks);
       var prevBlocks = [];
       var cutSheetNumber = 0;
       blocks = [];
       while (size(sortedBlocks) > 0) {
           // Run binary tree bin-packing algorithm
           Packer(definition.width, definition.height, definition.spacing, sortedBlocks, cutSheetNumber);
           for (var i = 0; i < size(sortedBlocks); i += 1) {
               var block = sortedBlocks[i];
               // Move parts to the binary tree bin packing location
               if (block[].fit != undefined) {
                   if (block[].rotated == true) {
                       rotateBlock(context, id, i ~ cutSheetNumber, block);
                   var fitVector = vector(block[].fit[].x, block[].fit[].y, 0*inch);
                   var transformToBin = transform(fitVector);
                   opTransform(context, id + ("transform_to_bin" ~ i ~ cutSheetNumber), {
                       "bodies": block[].owner,
                       "transform": transformToBin
               } else {
                   blocks = append(blocks, block);
           // Sketch cut sheets if specified
           if (definition.showSheets) {
               var sketch1 = newSketch(context, id + ("sketch" ~ cutSheetNumber), {
                       "sketchPlane" : qCreatedBy(makeId("Top"), EntityType.FACE)
               var newX = cutSheetNumber * definition.width * 1.1;
               skRectangle(sketch1, "rectangle" ~ cutSheetNumber, {
                       "firstCorner" : vector(newX, 0*inch),
                       "secondCorner" : vector(definition.width + newX, definition.height)
           // This condition checks that it is possible to space the parts, prevents infinite loop
           if (size(prevBlocks) != 0 && size(blocks) != 0 && prevBlocks == blocks) {
               println("Cut sheet is smaller than largest part plus twice the spacing");
               throw regenError(ErrorStringEnum.TRANSFORM_FAILED, ["cutSheet"]);
           } else {
               // Here you are left with whatever parts don't fit on the first cut sheet.
               // This loop runs once for each cut sheet.
               prevBlocks = blocks;
               sortedBlocks = sortBlocks(blocks);
               cutSheetNumber += 1;
               blocks = [];
   }, { });
   // Sort parts based on largest dimension
   export function sortBlocks(blocks is array) {
       var sortedBlocks = sort(blocks, function(block1, block2) {
           if (max(block2[].w, block2[].h) != max(block1[].w, block1[].h)) {
               return max(block2[].w, block2[].h) - max(block1[].w, block1[].h);
           } else {
               return min(block2[].w, block2[].h) - min(block1[].w, block1[].h);
       return sortedBlocks;
   // This is a helper function that rotates blocks in place so that they can be
   // placed either vertically or horizontally on the cut sheet.
   export function rotateBlock(context is Context, id is Id, unique is string, block is box) {
       var zaxis is Line = line(vector(0, 0, 0) * inch, vector(0, 0, 1));
       opTransform(context, id + ("rotate" ~ unique), {
              "bodies" : block[].owner,
              "transform" : rotationAround(zaxis, 90 * degree)
       const boundingBox is Box3d = evBox3d(context, {
              "topology" : block[].owner
       var transformToOrigin = transform(-boundingBox.minCorner);
       opTransform(context, id + ("translate" ~ unique), {
              "bodies" : block[].owner,
              "transform" : transformToOrigin
   // Modified binary tree bin packing from: https://github.com/jakesgordon/bin-packing/blob/master/js/packer.js
   // Initializer for the bin packing algorithm
   export function Packer(width is ValueWithUnits, height is ValueWithUnits, spacing is ValueWithUnits, blocks is array, cutSheetNumber) returns array {
       var root = new box({'x': cutSheetNumber * width * 1.1 + spacing, 'y': 0*inch + spacing, 'w': width - 2*spacing, 'h': height - 2*spacing, 'used': false});
       return fit(root, blocks, spacing);
   // Fit function calls findNode to determine recursively where the part fits on the sheet,
   // then calls splitNode to create a bin above and a bin to the right
   export function fit(root is box, blocks is array, spacing is ValueWithUnits) returns array{
       var node;
       var nodeR;
       var block;
       for (var n = 0; n < size(blocks); n += 1) {
           block = blocks[n];
           node = findNode(root, block[].w, block[].h);
           if (node != undefined) {
               block[].fit = splitNode(node, block[].w, block[].h, spacing);
           } else {
               nodeR = findNode(root, block[].h, block[].w);
               // See if a position can be found for the part if it is rotated
               // 90 degrees, if none is found in its original orientation
               if (nodeR != undefined) {
                   block[].fit = splitNode(nodeR, block[].h, block[].w, spacing);
                   block[].rotated = true;
               else {
                   block[].fit = undefined;
       return blocks;
   // Recursively finds a bin where the part will fit
   export function findNode(root is box, w is ValueWithUnits, h is ValueWithUnits) {
       if (root[].used) {
           var right = findNode(root[].right, w, h);
           var above = findNode(root[].above, w, h);
           if (right != undefined) {
               return right;
           } else if (above != undefined) {
               return above;
       } else if ((w < root[].w || tolerantEquals(w, root[].w)) && (h < root[].h || tolerantEquals(h, root[].h))) {
           return root;
       } else {
           return undefined;
   // Once a part is placed, creates a new bin above it and to the right of it
   export function splitNode(node is box, w is ValueWithUnits, h is ValueWithUnits, spacing is ValueWithUnits) returns box {
       node[].used = true;
       node[].above = new box({'x': node[].x, 'y': node[].y + h + spacing, 'w': node[].w, 'h': node[].h - (h + spacing), 'used': false});
       node[].right = new box({'x': node[].x + w + spacing, 'y': node[].y, 'w': node[].w - (w + spacing), 'h': h + spacing, 'used': false});
       return node;

Config file:

FeatureScript 275;
import(path : "onshape/std/geometry.fs", version : "275.0");
// This file contains the defaults for thickness, cut sheet width, cut sheet height, and spacing.
// Edit as necessary.
export const DEFAULT_THICKNESS =
   "min"        : -500 * meter,
   "max"        : 500 * meter,
   (meter)      : [1e-5, 0.0127, 500],
   (centimeter) : 1.27,
   (millimeter) : 12.7,
   (inch)       : 0.5,
   (foot)       : 0.04,
   (yard)       : 0.014
} as LengthBoundSpec;
export const DEFAULT_SHEET_WIDTH =
   "min"        : -500 * meter,
   "max"        : 500 * meter,
   (meter)      : [1e-5, 1.524, 500],
   (centimeter) : 152.4,
   (millimeter) : 1524,
   (inch)       : 60,
   (foot)       : 5,
   (yard)       : 1.7
} as LengthBoundSpec;
   "min"        : -500 * meter,
   "max"        : 500 * meter,
   (meter)      : [1e-5, 2.54, 500],
   (centimeter) : 254,
   (millimeter) : 2540,
   (inch)       : 100,
   (foot)       : 8.3,
   (yard)       : 2.8
} as LengthBoundSpec;
export const DEFAULT_SPACING =
   "min"        : -500 * meter,
   "max"        : 500 * meter,
   (meter)      : [1e-5, 0.00254, 500],
   (centimeter) : 0.254,
   (millimeter) : 2.54,
   (inch)       : 0.1,
   (foot)       : 0.0083,
   (yard)       : 0.0028
} as LengthBoundSpec;


  • mlaflecheCADmlaflecheCAD Onshape Employees, Developers Posts: 17
    This works so well, thanks so much for sharing!
    Mike LaFleche   @mlaflecheCAD
  • billy2billy2 Member, OS Professional, Mentor, Developers Posts: 874 PRO
    Very nice! Thanks for sharing.

  • shashank_aaryashashank_aarya Member Posts: 265 ✭✭✭
    Thanks very much for sharing!
  • viruviru Member, Developers Posts: 619 ✭✭✭✭
    Very nice! Thanks for sharing.

  • to_cato_ca Member Posts: 13
    Hi Marena,

    this is brilliant and works so well. Have looked through so many tools and addons to find a CAD program with a simple feature like this to enable simple laser cutting. My previous tool was clicking on each face, exporting them separately and then lining them up in another programme to get a DXF. This is 100x faster to iterate with. Thanks so much!
  • jochen333jochen333 OS Professional Posts: 27 PRO
    This really shows the power of feature script....

    Had to do a big assembly with a lot of sheets. It was really a pita generating all the dxf data for laser cutting.

    Tested your feature script with this assembly and it worked great...

    This will be a great relief in future.
  • Logan_5Logan_5 Member Posts: 4
    How do you add this to your own Onshape Part Studio?
  • lemon1324lemon1324 Member, Developers Posts: 123 EDU
    edited July 2017
    When you've got the auto layout document open, click the "+ Custom Features" button at the top left, just below the document name. That adds the feature to your own toolbar, it'll be at the right end, possibly in a dropdown with other custom features you've added.

    Arul Suresh
    PhD Candidate at Stanford University
  • Jake_RosenfeldJake_Rosenfeld Onshape Employees, Developers Posts: 726
    See the "Start using custom features" section of this page:
    Jake Rosenfeld - Modeling Team
  • brad_phelanbrad_phelan Member Posts: 80 ✭✭
    Hi there. I have tried to use the auto layout tool to arrange the parts for my "ant house". Most of the parts are 4mm thick with 3 of the parts 10mm thick. However the tool does not like my model. Is there something simple that I am doing wrong.


    Thanks for making the tool. I hope there is a solution to the problem.



  • Jake_RosenfeldJake_Rosenfeld Onshape Employees, Developers Posts: 726

    It appears that the feature gets unhappy with parts that have flat faces with internal edges.  I'm surprised that no one noticed this earlier, but it's any easy fix as it looks like the piece of code that does this doesn't actually do anything besides print out some debugging information.  I can post a new document with a fix, but I'd prefer to see if @marena_richardson is still around to make the fix on the original document.

    Technical details:
    The decomposeBody code at the very end of the feature calls traverseEdgesOfFace, which calls constructPath on qEdgeAdjacent(face, EntityType.EDGE).  constructPath will fail if it can't form a continuous path; in this case it fails because a face has more than one loop of edges:

    Jake Rosenfeld - Modeling Team
  • brad_phelanbrad_phelan Member Posts: 80 ✭✭
    Hi Jake, Thanks for that analysis. I'll wait to see if Marena posts a fix. We bought an ant farm for my boy for his birthday. I thought I might teach them some modelling with onshape, design a newer bigger enclosure then get it laser cut at http://www.formulor.de/. The auto layout will make transfering the design to the cutter much easier :)
  • kevin_o_toole_1kevin_o_toole_1 Onshape Employees, Developers Posts: 351
    edited March 19

    Looks like you're using a fork of the Auto Layout feature, not the original. Your forked version sets a variable with additional info about the paths around parts, but unfortunately that extra logic fails for parts that have holes in them (like yours).

    The easiest fix is to remove the forked Auto Layout feature from your toolbar, and instead add the Auto Layout feature from the original document which was linked at the top of this thread:
    EDIT: After doing that, you can delete and replace the feature in your feature tree

    Hope this fix arrives in time for your son's birthday!


  • Jake_RosenfeldJake_Rosenfeld Onshape Employees, Developers Posts: 726
    Nice catch @kevin_o_toole_1 !
    Jake Rosenfeld - Modeling Team
  • brad_phelanbrad_phelan Member Posts: 80 ✭✭
    Hi Kevin,

    Thankyou for that tip. It now works much better. I have two thicknesses in my model. 4mm and 1cm. When I select 4mm to be used by the auto layout then all the 4mm items are correctly collected and layout out.  <3 However the 1cm items are also moved but into some random position.

    This in itself is not really a problem. I thought I would then try to add another auto layout to collect the 1cm items into another sheet. But this destroys the 4mm layout

    Is there a suggested work around for handling multiple cut sheets with different thicknesses?
  • lemon1324lemon1324 Member, Developers Posts: 123 EDU
    Conveniently, I just made this improvement on my copy, here: https://cad.onshape.com/documents/576e01dbe4b0cc2e7f46a55d/v/5a1d3dddc86d8e47a1c0d6fc/e/887d6e2324589bfd2058c3e1
    Just add multiple auto layout features, and they'll get laid out in separate rows.  This version also works with the in-context->copy all in place->further operations workflow demonstrated in this document: https://cad.onshape.com/documents/590a2ea57be40f0ffec8ebee/w/83a9ff55ae7c041eaf0383f9/e/e8ddf59811c55ad691c5362b

    I also reached out to @marena_richardson via forum message to see if we could push my changes to the same document, but haven't heard in a few days, looks like she's likely not monitoring the forum anymore.
    Arul Suresh
    PhD Candidate at Stanford University
  • Jake_RosenfeldJake_Rosenfeld Onshape Employees, Developers Posts: 726

    Her profile says 'Last active May 2016'.  We probably won't be hearing back :)
    Jake Rosenfeld - Modeling Team
  • lemon1324lemon1324 Member, Developers Posts: 123 EDU
    Yeah, I was hoping for an email notification to get through.

    I'll get a standard pdf manual page up and get in touch with Neil to list my copy on community spotlight then so people can reference a document which has the possibility of updates, and if they find bugs I can fix them as I get time.
    Arul Suresh
    PhD Candidate at Stanford University
  • brad_phelanbrad_phelan Member Posts: 80 ✭✭
    The solution / workaround is to create new part studios and import the original part as a derived part.


    And then for each thickness create a new part studio.


  • lemon1324lemon1324 Member, Developers Posts: 123 EDU
    edited March 23
    Not sure if you missed my previous post, but I have a version that eliminates the need for that workaround, here:

    This version updates the FeatureScript to the current version, adds a couple other improvements, and will be updated if and when bugs turn up.

    Simply use multiple Auto Layout features, and each will lay out the new thickness parts in a new row, like this:
    Arul Suresh
    PhD Candidate at Stanford University
  • Marc_MillerMarc_Miller Member Posts: 39 ✭✭
    This auto layout is great.  And thank you @lemon1324 for your updates.

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