What determines the center of rotation when spinning the view?

Tony_C_

I'm trying to put my finger on how OS is selecting where my view center is when I'm spinning around the view using the RMB.

Is there something that determines it or is it selectable?

It's not really a problem on smaller parts/assemblies, but I find when I'm in a really big assembly it gets wonky. 

philip_thomas

Ok, i will give this a shot - this answer is based on my personal observation and recollections of conversations with the graphics guys!

1) If your cursor is over geometry, the center of rotation becomes the intersection of a ray drawn normal to the screen and the point of intersection on the body.
2) If the cursor is over whitespace - the center of rotation becomes the 'geometric center' of any entities 'close' to the point under the cursor - this includes things like the origin and any other parts or curves or surfaces. In testing i note that 'close' can be off the screen by quite a bit. There comes a point as you zoom in that those other entities no longer appear to be 'close' and are no longer included in the center calculation.

If you are struggling with rotating things - try;

• Putting your cursor over the point (on a part) that you want to rotate about.
• Hide the origin (if it's a long way away)
• Hide parts that you dont want to be considered 'close'

Not super exact - but it generally holds true and i hope this helps.
Hopefully someone that knows more about this than me will chime in if anything isn't clear/right.