RotateAround explanation.

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Can anyone explain me what is and how to use third parameter in RotateAround (angle).

Example image

How I think RotateAround works.

transform.RotateAround (target.position, new Vector3 (0, 1, 0), 90 * Time.deltaTime);

First parameter is the position around which we want the sphere B to rotate, so in my case it will be position of my Cube.

Second parameter is the axis around which it should rotate. Since it is (0,1,0), it will rotate around Y axis.

Third parameter is something I don’t know and/or understand.
What is angle?
If it is rotating then what is the work of angle. Even if I put 180 instead of 90, there is visually no difference.

Of course Time.deltaTime is tiny .

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var angle =5F; transform.RotateAround(Vector3.zero, new Vector3(0F,1F,0F), angle); it seems that the angle acts more like a speed increment-er rather that getting the angle based on the targets position

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2 Answers

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It was hard to understand how it works. The Unity documentation did not help me much (I asked about what confused me here)! I have drawn a picture I hope it helps to visualice to you all:

71872-20160610-164906.jpg
71872-20160610-164906.jpg2615×1656 391 KB

So if you change the angle, you will change the position within the green drawn circle…

I don't know what you tried tro link here, but it isn't a documentation page. ;) The documentation link would be: http://docs.unity3d.com/ScriptReference/Transform.RotateAround.html

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RotateAround does one single rotation around the given center point and axis by the amount specified in the third parameter. So if you call this once:

transform.RotateAround (target.position, new Vector3 (0, 1, 0), 90);

It would rotate the sphere around the cube by 90°. However if you call this method in Update, which means it’s being called each frame (at 60fps == 60 times per second) rotating by 90° wouldn’t make much sense as each frame it would be rotated 90°. So the given parameter specifies the speed how fast it rotates. Since the frame rate can vary you would get different speeds on different platforms / PCs /… By multiplying with Time.deltaTime you make the speed frame independent and the speed becomes time-dependent (like we usually measure speed, distance or angle in a certain amount of time).

90*Time.deltaTime

This actually returns a fractional angle which is modified for the current framerate so if you accumulate those fractions they will add up to 90° after 1 second. So you have a rotation speed of one (360°) rotation in 4 seconds or 15 rpm.

When you use 180 instead of 90 it should rotate twice as fast.