Hi community, i'm currently trying to understand how the various 
camera-manipulators work (trackball, terrain, ufo, etc.) and several questions 
arrived:

- the first thing that confused me was, that Y/Z-vector directions are now the 
openGL-way. (is there a reason why OSG normally uses Y as forward-vector?)

- i also often encounterd the functions "getCoordinateFrame(Vec3&)" and 
"getUpVector(cf)", e.g:

Code:

CoordinateFrame eyePointCoordFrame = getCoordinateFrame( eye )
        if (intersect(eye+getUpVector(eyePointCoordFrame)*distance,...



i have not much practice with matrix transformations, so its a little bit hard 
for me to understand the sense of this, but i assume the following: eye is the 
position of the camera, and the camera has it's own local coordinate-system. 
getCoordinateFrame() / getXVector() provide the world coordinates from such 
local coordinate frame. 

i looked up the implentation of getCoordinateFrame(), but i couldn't find out 
how it is accomplished, can you explain me how this is done?



Thanks in advance, 
Christian

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http://forum.openscenegraph.org/viewtopic.php?p=13315#13315





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