there is an issue with 3d rotate command
there is no issue, this is the mathematical calculation:
To rotate a point around the Y-axis, you can use the following rotation matrix for a 3D rotation:
In this case, since you want to rotate around the Y-axis by 90 degrees, the rotation matrix becomes:
To apply this rotation matrix to the point (15, 15, 15) with a base point of (10, 10, 10), you subtract the base point from the point you want to rotate, apply the rotation, and then add the base point back:
New point=Ry(90∘)⋅(Point−Base point)+Base point
First, calculate the vector difference:
Now, apply the rotation matrix:
Finally, add the base point:
Therefore, the new coordinates after rotating the point (15, 15, 15) around the Y-axis by 90 degrees with a base point of (10, 10, 10) are (15, 15, 5).
If you rotate by an angle of -90 the new transformation matrix becomes:
From there you can easily see that the new coördinate is either (15,15,5) or (5,15,15) depending on the direction of your rotation.
There is no issue, your math was wrong.
Hi,
1. You still not said what command you are talking about. As stated above, there are two of them.
It sounds you are talking command "ROTATE3d", not 3Drotate.
2. >>It is very simple, I want to rotate a point with coordinates of (15,15,15) around Y axis.
The angle of rotation is 90 degrees, and the coordinates of base point are (10,10,10).
>>The result must be (15,15,-15),
If you have a point at z=15 and you want a result of z=-15 after "90"rotation, your basepoint
has to be on Z=0, but you want to rotate around Z=10, this will never work this way.
3. >>The result from AutoCAD is different with the mathematical calculation.
The fail is your math and the three-dimensional imagination
Also: You still not talking about your rotation direction, what is default anti-clockwise, how is it in your case?
4. >>I am lucky to pick up this issue before uploading thousands of thousands points into AutoCAD for processing.
Right, you have to learn a tool before using in in the productive system, especially when it comes to mass processing
We don't know where you stumble, but something is wrong between your imagination and your applied mathematical path.
Often it is just a wording, but your sample data (15,15,15, 90°around 10,10,10 => 15,15,-15 will never true.
