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Problem with determining interference and if sides are touching in onshape feature script
matthew_rosete380
Member Posts: 10 ✭
So I started working on a new project and had a little problem with interference error messages. It would never send the error message no matter what I do and would always merge. How do I fix this note it is on line 220.
Here is the document: https://cad.onshape.com/documents/94e2ca3c499ecbba9ccfafe6/w/c35c00116423894cfa81ae88/e/1fd4bc6d010a97fc9bf50bf5
Best Answer
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NeilCooke
Moderator, Onshape Employees Posts: 5,838 
qIntersection finds the common entities between two lists of entities (nothing to do with boolean intersections), so in line 202 it says: give me all entities that exist in list 1 and in list 2 (which is all entities minus all those in list 1) so the result will always be nothing with a volume of zero m^3.
Senior Director, Technical Services, EMEA0
Answers
I added a few println messages to find that it never goes into the if, but always goes to the else.
so apparently there's something wrong with your volume == 0^3 meter test.
at first i thought perhaps the result is 0.00000000001 but it won't show that with a println, so i tried volume < 0.00001^3 meter
I received an error (after putting it into a seperate constant, the error is readable) stating:
strange how this wouldn't show up for "volume == 0^3 * meter" because there you're making a unit error as well... @ilya_baran: is this a bug?
so change your if condition to: "volume == 0 * meter^3" and it should work appropriately.
So Now it just doesn't throw the message at all and always says 0 meters cube for the volume of interference even when it intersects other objects
A less than or greater than needs to have the same type, same with a number of other operators. But the == does not require the type to be the same, a mismatch in type will just be false.
0^3 * meter is wrong because the cube needs to be on the units not the value. Its a comparison of linear units to volume.
@matthew_rosete380
Your current code doesn't work because you aren't doing an actual boolean intersection operation.
qIntersection is a query intersection, no geometry is modified, so your query for intersection is empty.
"intersection" which you are taking the volume of is the intersection of your loft query, and (all bodies with loft body removed), which is empty.
use addDebugEntities to visually debug your queries. If volume is 0, it might be because the query is empty…
Custom FeatureScript and Onshape Integrated Applications
qIntersection finds the common entities between two lists of entities (nothing to do with boolean intersections), so in line 202 it says: give me all entities that exist in list 1 and in list 2 (which is all entities minus all those in list 1) so the result will always be nothing with a volume of zero m^3.