Stereoscopic view, glFrustum

Akiko · Post by **Akiko** » Sun Mar 20, 2005 8:50 pm

Hi.
Sorry if it isn’t advanced topic.

I need to set up stereo view – two viewports and two cameras with different position. I’ve read posts about multiple cameras but now my question is a little different.

In stereoscopic the best results we get using asymmetric view –
(I am not sure the definition but in opengl we can set it with glFrustum(left, right, bottom, top, near, far) ).
Symmetric view is when top=-bottom and left=-right (glPerspective (fov, aspect, near, far) ).

I suppose Irrlicht cameras are symmetric.
I wonder if there is any way to get asymmetric one, e.g. modifying projection matrix.

Thanks in advance.
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Guest · Post by **Guest** » Mon Mar 21, 2005 2:01 pm

Actually... there's only one difference between the projection of the left eye and right eye...

One's to the left and the other is to the right. (Plus there's a nose in the way)

In other words, there is no difference in the projection, only in the position of the camera.

Guest · Post by **Guest** » Mon Mar 21, 2005 2:06 pm

...to answer the question of how to change the projection matrix:

virtual void irr::scene::ICameraSceneNode::setProjectionMatrix ( const core::matrix4 & projection ) [pure virtual]

Sets the projection matrix of the camera. The core::matrix4 class has some methods to build a projection matrix. e.g: core::matrix4::buildProjectionMatrixPerspectiveFovLH. Note that the matrix will only stay as set by this method until one of the following Methods are called: setNearValue, setFarValue, setAspectRatio, setFOV.

Parameters:
projection: The new projection matrix of the camera.

katoun · Post by **katoun** » Mon Mar 21, 2005 5:46 pm

Stereoscopic view is a little diferent:
Each eye is like a normal camera but hulf of each one's view intersect but the image is made by the brain that liks them together .
For games I think you should have to cameras and yes with asymetric progecton one having the center to the left the other to the right and use to viewports but I thing sliping the view in juf you change the aspect ratio for each camera and the value of the aspect ration is Width/Height. Then is should be set to hulf of the Width (meaning Withdth/2*Height).
Think about it you just cannt put one viewport over the other to cross them togheder because I've tried that and it dosent get nice.

Akiko · Post by **Akiko** » Thu Mar 24, 2005 10:24 pm

Thanks for answer,

only moving camera to left and right (even if we have nose

) doesn't look nice.
I will try to build projection with builProjectionMatrix...(...) function and than change some values by hand before setting it on camera.