I'm trying to learn the fundamentals of 3d computer graphics by writing a toy framework in WebGL.
I'm currently working on mouse based camera controls. There are plenty of good resources in the ACM SIGGRAPH library to be found, but there are some aspects of this area that I can't find answers to.
A lot of orbit controls simply use the origin as the pivot point, but other implementations can orbit around any arbitrary point in a scene and the camera stays 'still'. I'm trying to implement the latter.
It seems that a good way to do this would be to simply get the cross product of the two vectors made by the pivot point and 3d coords of the corresponding pixels on the image plane, but I can't anything like this approach anywhere which leads me to believe I've misunderstood some fundamental aspect of image projection/image planes.
Is the image plane an abstract construct that doesn't really have 3d coords or can pixels in the image plane actually be mapped to world coords?