Rotation Matrix :45 degrees about point (5,5,0)

On-line book about AutoCAD VBA, the elements on the matrix states that:
0.707107 -0.707107 0.0 5.0
0.707107 0.707107 0.0 -2.071068
0.0 0.0 1.0 0.0
0.0 0.0 0.0 1.0

I've followed some literature about matrix translation and transformation
and got the following elements:
0.707107 -0.707107 0.0 0.0
0.707107 0.707107 0.0 -7.07107
0.0 0.0 1.0 0.0
0.0 0.0 0.0 1.0

Please suggest me how comes the elements are different and correct my
mistake.

Thanks.
Richard Khaw
Torrance, California.

 

Do you *need* to know the numbers in the matrix? AutoCAD provides the methods GetUCSMatrix and TransformBy for matrix manipulation and the actual values normally wouldn't be of interest. The TranslateCoordinates method is another way to manipulate objects between coordinate systems.

Perhaps if you explain a bit about what you're trying to do we can help more.

Regards

Wayne Ivory
IT Analyst Programmer
Wespine Industries Pty Ltd

 

Not sure what you mean by 'the actual values normally wouldn't be
of interest'. The TransformBy method takes a matrix, and was not
specifically intended to be the matrix returned by GetUCSMatrix,
it can be any matrix that may be composed manually, or obtained via
other means.

Also, TranslateCoordinates doesn't do much for transforming
objects.



AcadX for AutoCAD 2004 Beta 1
http://mysite.verizon.net/~vze2vjds/acadx/AcadX16.zip

manipulation and the actual values normally wouldn't be of interest. The TranslateCoordinates method is another way to
manipulate objects between coordinate systems.

 

True, I realised after I posted that only in some cases would there be an existing object which you could apply a GetUCS method to (I guess I had the blinkers on because that's the way I've used those methods).

The reference to TranslateCoordinates was indicating another possible approach to the bigger picture which may or may not be relevant, hence the request for more information. For example I've created a bunch of objects "relative" to a target object by creating a UCS for it and then "transforming" all the new objects using TranslateCoordinates. Maybe that's unusual - I don't know - I was starting from the ground up at that stage and it produced the desired result.

Regards

Wayne