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Where can I find the meaning of the number in the transform property from the API?
kevin_dolfing
Member Posts: 5 ✭
Hello, I am doing a prototype with the OnShape API for an internship, which involves showing an assembly in GLTF on another webpage. So far I've been able to work my way through the API except this. When I get the data for an assembly I get a occurrences.transform property that looks like this:
<div>transform: [</div><div> 1,</div><div> 0,</div><div> 0,</div><div> -0.11526866659459908,</div><div> 0,</div><div> 1,</div><div> 0,</div><div> -0.02565412583836096,</div><div> 0,</div><div> 0,</div><div> 1,</div><div> 0.01184993247305625,</div><div> 0,</div><div> 0,</div><div> 0,</div><div> 1</div><div>]</div>
How do I know what these values stand for? I've looked around, but can't seem to find any definition for these. I assume index 3, 7 and 11 are x y and z respectively, but what about the other values.
Edit: Looks like the code block didn't get posted right. So here's a hastebin link: https://hastebin.com/nogivuporo.yaml
Edit 2: Further investigation leads me to believe that index 2, 6 and 10 represent the rotation, though these numbers don't seem to line up with radians, degrees or gradiens? Is there some catch with this?
Edit: Looks like the code block didn't get posted right. So here's a hastebin link: https://hastebin.com/nogivuporo.yaml
Edit 2: Further investigation leads me to believe that index 2, 6 and 10 represent the rotation, though these numbers don't seem to line up with radians, degrees or gradiens? Is there some catch with this?
0
Best Answer
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caden_armstrong2
Member, User Group Leader Posts: 127 ✭✭✭
The transformation matrix is a 4x4 matrix comprised of a rotation matrix, translation array, uniform scale, and i think non-uniform scale(? havent confirmed this, but it doesn't matter in most use cases).
the indices
0,1,2
4,5,6
8,9,10
Are the rotation matrix.
indicies
12,13,14
3,7,11
are the translation array
index 15 is the scale parameter (default to 1)
And the indicides
3,7,11
12,13,14
I believe are non-uniform scaling, but I have tested them, these should be set to zero.
Its possible they aren't supported.
Peter Brinkhuis has written a great article about transformations specific to the solidworks api here
A lot of it applies to the onshape transform, but the indicies are in a different order.1
Answers
the indices
0,1,2
4,5,6
8,9,10
Are the rotation matrix.
indicies
12,13,14
3,7,11
are the translation array
index 15 is the scale parameter (default to 1)
And the indicides
3,7,11
12,13,14
I believe are non-uniform scaling, but I have tested them, these should be set to zero.
Its possible they aren't supported.
Peter Brinkhuis has written a great article about transformations specific to the solidworks api here
A lot of it applies to the onshape transform, but the indicies are in a different order.
I had it confused with the view matrix, which is transposed from the transform matrix.
Thank you! That's exactly what I was looking for… :-)