[osg-users] How to Convert Lookat to Projection and View Matrices

[Sebastian Messerschmidt]

Am 22.09.2015 um 16:08 schrieb Erik Hensens:
> Thank you for the reply Glenn!
>
> You say that the projection matrix doesn't depend on the lookat parameters; what does it depend on?
The projection matrix depends on the size of your viewing frustum. 
Usually near/far plane and the dimensions (angles) of the field of view.
You can use the camera->get/setProjectionMatrix functions here.
For instance:

viewer->getCamera()->setProjectionMatrixAsFrustum(
         aspect_x * near_plane * left_angle,
         aspect_x * near_plane *right_angle,
         aspect_y * near_plane * bottom_angle,
         aspect_y * near_plane * top_angle,
         near_plane,
         far_plane
     );

Cheers
Sebastian
>
> Thanks in advance!
>
>
> gwaldron wrote:
>> You can make the view matrix:
>>
>>    osg::Matrix::lookAt(eye, center, up)
>>
>>
>> This has nothing to do with the projection matrix though; that doesn't depend on your look vector.
>>
>> Glenn Waldron
>>
>>
>>
>>
>> On Tue, Sep 22, 2015 at 9:24 AM, Erik Hensens < ()> wrote:
>>
>>> Hi everyone!
>>>
>>> How can I compute the view matrix and the projection matrix from a set of lookat parameters (eye, center, and up)?
>>>
>>> I'm asking because I need to compute the MVPW for a given lookat before the camera is actually at that lookat.
>>>
>>> I'm totally stumped and any help would be greatly appreciated!
>>>
>>> Thank you!
>>>
>>> Cheers,
>>> Erik[/list]
>>>
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