Camera and LookAt controll

[hasanshamsijeze]

hi i need to control camera for example rotate camera move camera and do every work can done with camera but i have a problem.
to control camera i use of vsd::lookat class i can move camera by eye but to rotate camera i have problem.
there are a rotate function in vsg::Trackball class but this function rotate earth not camera.
for example you thing is on the ground and want to see sky so i can not do this work. or you are under an airplane and want to see ground of airplane so you can see earth but no of airplane.

[robertosfield]

I can't give you an answer as I am not able to understand your needs based on what you have written. I'm struck having to ask you questions to find out the proper context of your needs.

What type of application do you have?

What range of views and how do you want to control them?

[hasanshamsijeze]

i work on earth model to show airplane a need two type of view
one-> I am on earth and show airplane so need to move camera on earth example latitude 10 and longitude 10 and height 30m. next watch sky to see air plane.
two-> I am as a pilot in to airplane and see earth next can change see point to left and right , up and down

my view range is 2000km top of earth

[robertosfield]

The vsg::Trackball event handler is an example of interactively controlling the camera view, but it's not ideal for all applications.

For your usage case I would just write your own camera event handlers to manage the user interaction, or implement your own scene object tracking that sets up the camera view matrices in an appropriate manner. Only you will now precisely what you are after to we can only point you in the right direction.

[robertosfield]

I recommend learning about the vsg::ViewMatrix base class and it subclasses, these are found in the ViewMatrix header:

https://github.com/vsg-dev/VulkanSceneGraph/blob/master/include/vsg/app/ViewMatrix.h

The vsg::Camera uses the vsg::ViewMatrix interface to get the view matrix used in the RecordTraversal.

[hasanshamsijeze]

thanks for your answer i implement my custom visitor to control camera but there is a problem. camera never rotate over than 90 degree to up
when i rotate over than 90, camra view go to back of its but i want to see sky

[robertosfield]

We don't know your background level of knowledge on scene graphs, vector + matrix maths, and we don't know what code you've implemented so it's not possible to provide any specific advance on how to resolve the problem you still have.

As a general comment, the vsg::dmat4 view matrix is fully capable of specifying your look position and direction in any position and any direction. You can also use a vsg::dvec3 for positioning, and vsg::dquat for rotation which you can then use to set up the view matrix. The new vsg::LookDirection class combines these two so might be a good starting place.

There also lots of online resources explaining vector, quaternions and matrix maths in the context games/visual simulation so have a search online so help you understand the general concepts, then the VSG code base and examples for how the VSG classes that provide this functional work at the API level.

[rolandhill]

Hi Hasan, You can use Trackball::setViewpoint() to position the camera however you want /// set the LookAt viewport to the specified lookAt, animating the movements from the current lookAt to the new one. /// A value of 0.0 instantly moves the lookAt to the new value. void setViewpoint(ref_ptr<LookAt> lookAt, double duration = 1.0); You can also derive your own Trackball class from vsg::Trackball. From there you can expose the _lookAt class or write your own camera manipulation methods. Roland Hill Director Four Winds Technology Pty Ltd Spatial Integration <https://www.spatialintegration.com/>

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On Mon, 3 Feb 2025 at 23:36, hasan ***@***.***> wrote: hi i need to control camera for example rotate camera move camera and do every work can done with camera but i have a problem. to control camera i use of vsd::lookat class i can move camera by eye but to rotate camera i have problem. there are a rotate function in vsg::Trackball class but this function rotate earth not camera. for example you thing is on the ground and want to see sky so i can not do this work. or you are under an airplane and want to see ground of airplane so you can see earth but no of airplane. — Reply to this email directly, view it on GitHub <#1385>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAPOEQY76KBTBKINAEQRIFD2N5PEVAVCNFSM6AAAAABWMAAYFOVHI2DSMVQWIX3LMV43ERDJONRXK43TNFXW4OZXHEYTAMJZGI> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[hasanshamsijeze]

i know that. but on lookAt i have 3 value (see,center,up) my question is how set these 3 value to show my custom view
i know about see (this is camera location) but i don't know about center ant up argument

[robertosfield]

vsg::LookAt uses the same conventions are gluLookAt. This is done for historical reasons to help users who are used to OpenGL migrate more easily to the VSG. Do a search online for gluLookAt documentation/examples as these might provide the best insight to what each part does.

I might be that vsg::LookDirection might be a more appropriate class. What class or even custom vsg::ViewMatrix is most appropriate depends upon your specific needs.