Re: [Visualpython-users] rotation of camera

[Bruce S. <Bru...@nc...>]

Oh, now I see your point. I did misread the original question. (I didn't even 
realize that there is a Visual function "radians"! I better get this into the 
documentation.)

But there's nothing wrong with the radians function: it's doing its job of 
converting radians(90) into pi/2 radians. The problem is that in the first 
iteration through the loop the rotation is through 0, the next time through 1 
degree, the next time through 2 degrees STARTING FROM A DIRECTION THAT HAD 
ALREADY BEEN ROTATED 1 degree, so the new direction is 3 degrees away from the 
original direction. The next rotation will be by 3 degrees, for a total rotation 
of 6 degrees, etc.

So my corrections to those programs should have said

	....rotate(angle=radians(1), .....

That way one is always rotating by 1 degree each time through the loop.

Bruce Sherwood

Lenore Horner wrote:
> The command "radians" which he was using to turn his degree angles into 
> radian angles.
> 
> On Apr 18, 2009, at 12:48 , Bruce Sherwood wrote:
> 
>> What is there to squawk about? 90 radians is a completely legal angle.
>>
>> Bruce Sherwood
>>
>> Lenore Horner wrote:
>>> VPython doesn't have a radians command to turn degrees into radians?  
>>> Shouldn't it squawk when he uses an illegal command?
>>> Lenore
>>> On Apr 18, 2009, at 11:40 , Bruce Sherwood wrote:
>>>> The angle used by rotations must be in radians, not degrees.
>>>>
>>>> You want ....rotate(angle=alfa*pi/180, ....
>>>>
>>>> Bruce Sherwood
>>>>
>>>> alessandro wrote:
>>>>> I want to rotate 90° around the center objects  with an animation. I
>>>>> tried this:
>>>>>
>>>>>
>>>>> from visual import *
>>>>> ball = sphere(pos=(-5,0,0), radius=0.5, color=color.red)
>>>>> wallR = box(pos=(6,0,0), size=(0.2,4,4), color=color.green)
>>>>> alfa=0
>>>>> while alfa < radians(90):
>>>>>   rate(20)
>>>>>
>>>>>   scene.forward = scene.forward.rotate(angle=alfa, axis=(0,1,0))
>>>>>
>>>>>   alfa += radians(1)
>>>>>
>>>>> both the sphere & box rotate but they rotate for not only for 90° but
>>>>> serveral time. Where is the error?
>>>>>
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>