Re: [pygame] rotate around point

tks all

2012/8/21 Silver <rockachu2@xxxxxxxxx>

try using math.sin() and math.cos()

for example:

lets call the position of the shoulder shoulderPosition which is a tuple
(0,0)
lets call the angle you want to rotate it to angleShoulder (in radians,
to convert from degrees use math.radians()
lets call the length of the upper arm upperArmLength

then

elbowPosition =
(upperArmLength*math.cos(angleShoulder)+shoulderPosition[0],
upperArmLength*math.sin(angleShoulder)+shoulderPosition[1])

then you can center your image there and rotate it.

Heres an image on how it works

On 8/21/2012 10:08 AM, Ricardo Franco wrote:
> Hi, guys. Tks for the answers, but I didnt understand how to rotate it yet.
> I made a workaround by putting my arm image inside a blank square cover, so
> the center of the image is where I want.
> This way I can rotate around the center and get the spected result with the
> arm -> shoulder joint.
> But I cant get a good result within forearm -> arm joint.
>
> 2012/8/20 Christopher Night <cosmologicon@xxxxxxxxx>
>
>> Right, but note that performing step 2 with pygame.transform.rotate is not
>> trivial, since it doesn't rotate about the origin, or any particular point
>> for that matter: the fixed point of rotation depends on the surface
>> dimensions and the rotation angle. So your step 2 is itself 3 steps.
>>
>> For this reason, I generally anchor all my blits to the surface's center.
>> In this case I would make it easy on myself by adding some margin to the
>> image so that the desired rotation point is at the center of the image. I
>> know not everyone likes to do it that way, though.
>>
>> -Christopher
>> On Aug 20, 2012 4:32 PM, "Mark Wexler" <mark.wexler@xxxxxxxxx> wrote:
>>
>>> To rotate around an arbitrary point,
>>> 1. subtract (vectorially) the center of rotation;
>>> 2. perform rotation (as if about the origin);
>>> 3. add the center of rotation.
>>>
>>> Mark
>>>
>>>
>>> On Mon, Aug 20, 2012 at 10:10 PM, Ricardo Franco
>>> <ricardo.krieg@xxxxxxxxx> wrote:
>>>> Hi, I need to rotate around a specific point.
>>>> It's a person animation. So the arms should rotate over the shoulders'
>>>> point.
>>>> How to do that?
>>>>
>>>> --
>>>> Ricardo Franco Andrade @ricardokrieg
>>>>
>>>> ( Game | Desktop | Web ) Developer
>>>>
>>>> email: ricardo.krieg@xxxxxxxxx
>>>> contact: +55 (86) 9958 9725
>>>> +55 (86) 9436 0830
>>>> twitter: twitter.com/ricardokrieg
>>>> facebooK: https://www.facebook.com/krieg.ricardo
>>>> github: https://github.com/ricardokrieg
>>>>
>>>
>>>
>>>
>>> --
>>> Mark Wexler
>>> Laboratoire Psychologie de la Perception
>>> CNRS - Université Paris Descartes
>>> 45, rue des Saints-Pères
>>> 75006 Paris, France
>>> http://wexler.free.fr
>>>
>>
>
>

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Ricardo Franco Andrade @ricardokrieg

( Game | Desktop | Web ) Developer

email: ricardo.krieg@xxxxxxxxx
contact: +55 (86) 9958 9725

+55 (86) 9436 0830
twitter: twitter.com/ricardokrieg

facebooK: https://www.facebook.com/krieg.ricardo

github: https://github.com/ricardokrieg