Re: [PyOpenGL-Users] recommendation for setting correctly the new direction of an object

[Roland E. <r.e...@gm...>]

Thanks for the example and the explanation, I will have a look at it asap.

Roland.


Le 08/03/10 17:01, Mike C. Fletcher a écrit :
> On 10-08-02 04:57 PM, Roland Everaert wrote:
>> Hi,
>>
>> I am currently writing a third person view space shooter where the
>> player can freely fly in the "map". I want to define an arcade flying
>> model like in most space shooter or spaceship simulation, but I face the
>> problem of specifying the transformation right.
>>
>> For the moment, my scene contains the player space ship pointing toward
>> the negative z axis, with the camera a little bit behind it. In front of
>> the ship there are 2 objects. When I apply some thrust to the player
>> spaceship it goes forward, but if I turn the ship, it is not changing
>> direction, while the ship and the camera are turning.
>>
>> My questions are the following:
>>
>> 1. Given the code below, why have I to call the method
>> self.__chasingView() after rendering the player's ship?
>>
>> 2. How to change the direction of the ship? Am I missing some glRotate()
>> functions somewhere in the code or should I change the code of method
>> setNewPosition() in such a way that the position of the ship is computed
>> on all 3 axis?
>>    
> The problem you are facing is that you want to make the motion of the 
> ship (x,y,z) modify by currentrotation * motionvector.  You *could* do 
> that with an ever-increasing set of glRotate/glTranslate calls (you'd 
> need one for every change in direction), but what you really want to 
> do is to track your position in "world" space and change that position 
> by currentrotationmatrix * motionvector.
>
> I normally do that with a wrapped Quaternion class in OpenGLContext.  
> See OpenGLContext/move/viewplatform.py for the code that wraps it 
> (particularly the relativePosition() method, on which all of the 
> various forward/sideways/up/down movements are built.
>
> http://bazaar.launchpad.net/~mcfletch/openglcontext/trunk/annotate/head:/OpenGLContext/move/viewplatform.py 
> <http://bazaar.launchpad.net/%7Emcfletch/openglcontext/trunk/annotate/head:/OpenGLContext/move/viewplatform.py>
>>       def setNewPosition(self):
>>           self.addToPosition(z=-(self.thrust * self.tick))
>>    
> that should be something like self.addToPosition( self.thrust * 
> self.tick * self.orientation )
>
> HTH,
> Mike
> -- 
> ________________________________________________
>    Mike C. Fletcher
>    Designer, VR Plumber, Coder
>    http://www.vrplumber.com
>    http://blog.vrplumber.com
>    
>
>
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