topic Re: Fusion 360 API units in Fusion API and Scripts Forum

Fusion 360 API units

yebyps — Tue, 31 Mar 2020 08:08:32 GMT

I'm a complete newbie to API. I found a script, and got it to run with a bit of badgering, and also discovered how to stepover in the debugging mode. What the script does is the wrong scale for me and I want to change probable cm to mm as in my normal unit mode. What I have at the beginning of the (python) code is

import adsk.core, adsk.fusion, traceback, math

def run(context😞

ui = None

try:

app = adsk.core.Application.get()

ui = app.userInterface

mm = design.unitsManager.defaultLengthUnits

des = adsk.fusion.Design.cast(app.activeProduct)

root = des.rootComponent

the addition of mm = design.unitsManager.defaultLengthUnits to an otherwise functioning code results in total silence when I try to run the code. When I step in debug mode, it drops out at that line. Obviously I'm missing some previous declaration, but I'm too new to the grammar to figure that out. Any ideas please.

Re: Fusion 360 API units

JesusFreke — Tue, 31 Mar 2020 08:35:51 GMT

A few things:

First, on the problematic line:

mm = design.unitsManager.defaultLengthUnits

you are trying to access the "unitsManager" member of the object contained in the design variable - but the design variable has not been defined yet -- but you retrieve the design just a couple of lines down:

des = adsk.fusion.Design.cast(app.activeProduct)

Although you assign it to the "des" variable, not the design variable.

Also, I'm not sure what your intention is with the line

mm = design.unitsManager.defaultLengthUnits

I'm guessing that you're trying to change the defaultLengthUnits to mm, but that line doesn't do that. Instead, it is simply retrieving the existing value of defaultLengthUnits and assigning it to a variable with the name "mm". However this is just a local variable with no intrinsic meaning. The value of the "mm" variable after this line would typically be either the string "in" or the string "cm", depending on which is the default in the current design. defaultLengthUnits is a read-only property, so you can't use it to change the default.

And finally, it's generally a good practice to wrap your script with a try/except block, and either print the exception or show a dialog with the exception. In this case, an exception is being thrown at the line I previously mentioned, and the error message would tell you what was wrong. It would likely be something along the lines of "accessing undefined variable 'design'".

For example, something like:

import adsk.core, adsk.fusion, traceback, math def run(context:disappointed_face: ui = None try: app = adsk.core.Application.get() ui = app.userInterface design = adsk.fusion.Design.cast(app.activeProduct) root = design.rootComponent mm = design.unitsManager.defaultLengthUnits except: if ui: ui.messageBox('Failed:\n{}'.format(traceback.format_exc()))

I'm not positive, but I'm not aware of a way to change the default units to mm. Although I do agree with you in that I prefer to work in mm instead of cm/in. I typically do everything as if the units were mm, and then just scale the end result by 1/10 at the end.

Re: Fusion 360 API units

goyals — Tue, 31 Mar 2020 11:44:08 GMT

Please take a look at https://forums.autodesk.com/t5/fusion-360-api-and-scripts/change-units-with-api/td-p/8208839

Re: Fusion 360 API units

BrianEkins — Tue, 31 Mar 2020 17:09:08 GMT

You might also find this useful.

http://help.autodesk.com/view/fusion360/ENU/?guid=GUID-A81B295F-984A-4039-B1CF-B449BEE893D7

Re: Fusion 360 API units

samputzi — Wed, 15 Apr 2020 09:18:06 GMT

Hi thanks for the great resources

maybe i can‘t see it but the example codes on this link: http://help.autodesk.com/view/fusion360/ENU/?guid=GUID-A81B295F-984A-4039-B1CF-B449BEE893D7

are just in javascript and don‘t show either python or c++. Do you know of another ressource with python code?

Re: Fusion 360 API units

BrianEkins — Wed, 15 Apr 2020 16:18:42 GMT

You're right. That's some very old content that somehow slipped through when the JavaScript API was retired. It needs to be updated. Here's a version of the first snippet in Python.

design = adsk.fusion.Design.cast(app.activeProduct) unitsMgr = adsk.core.UnitsManager.cast(design.unitsManager) # Prompt the user for a string and validate it's valid. isValid = False default = '1 in' # The initial default value. value = '' while not isValid: # Get a string from the user. (value, isCancelled) = ui.inputBox('Enter a distance', 'Distance', default); # Exit the program if the dialog was cancelled. if (isCancelled): return # Check that a valid length was entered. if unitsMgr.isValidExpression(value, unitsMgr.defaultLengthUnits): isValid = True else: # Invalid expression so display an error and set the flag to allow them # to enter a value again. ui.messageBox('"' + value + '" is not a valid length expression.', 'Invalid entry', adsk.core.MessageBoxButtonTypes.OKButtonType, adsk.core.MessageBoxIconTypes.CriticalIconType) # Use the value for something. realValue = unitsMgr.evaluateExpression(value, unitsMgr.defaultLengthUnits) ui.messageBox('input: ' + value + ', result: ' + str(realValue))

Re: Fusion 360 API units

Anonymous — Thu, 16 Apr 2020 20:18:26 GMT

Hello, newbie here.

1. So from my understanding and what I've tried, this code changes the default unit of the current document

unitsMgr = design.fusionUnitsManager

unitsMgr.distanceDisplayUnits = adsk.fusion.DistanceUnits.InchDistanceUnits

It works great to change the default units, but how can I change the unit system of the API? What I mean, if for instance, I create a sketch with a 1x1 square in it, regardless of my default unit of the design, it'll always be 1cm x 1cm. Can I change that and if yes, how? Below is how I did my 1in x 1in square, but is there a more elegant way of doing it?

cmToInches = 2.54 usLength = 3 usWidth = 4 usHeight = 1 edgLength = cmToInches * usLength edgWidth = cmToInches * usWidth edgHeight = cmToInches * usHeight edges = sketch.sketchCurves.sketchLines cubEdges = edges.addCenterPointRectangle(adsk.core.Point3D.create(0, 0, 0), adsk.core.Point3D.create(edgLength/2, edgWidth/2, 0)) cubEdges.item(2) cubProfile = sketch.profiles.item(0)

Thank you for your help

Re: Fusion 360 API units

BrianEkins — Thu, 16 Apr 2020 20:20:27 GMT

The API is a layer over the Fusion internals that tries to be as thin as possible. Internally, length units within Fusion core are _ALWAYS_ in centimeters. The API reflects that so there's not any way to change it. In most programs, the only time you have to care about units is when you get values from the user and when you display values. In both of those cases, you can use utilities in the API to convert the user input to internal units and to create a string in the current document units to display.

Also, if you're not commenting on an existing topic, it's best to create a new one for your new question, even if it is related to a previous question.

Welcome to the Fusion 360 API.