CGTalk - Simple angle calculation

View Full Version : Simple angle calculation - why wrong?

RyuMaster

02-19-2012, 07:36 AM

Hi! I have this simple formula to calculate angle between 2 points:

theAngle = acos(dot (normalize p1) (normalize p2))

Now, I get 2 points from UVW elements selection. I want to track its rotations. So, lets say, I get angle 24 from the very start.

Then I take my selected UVW eleement, scale it down.

theAngle value is now 14! But why? I just scaled it down, no rotation so far. So I assumed relative rotation between 2 points of element would stay the same?

RyuMaster

02-19-2012, 10:28 AM

Don't mind my question now. I realized I should compare vector lines, not points, for angles. Hope that will do the trick

Kickflipkid687

02-19-2012, 03:49 PM

Yeah, that is right, 2 lines. There is a sticky in here with forumlas that has what you need.

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02-19-2012, 03:49 PM

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