camera.jl

function movecam{T}(state0::Rotatable{T}, state1::Rotatable{T})
	xangle 		= state0.xangle - state1.xangle #get the difference from the previous state
	yangle 		= state0.yangle - state1.yangle
	zoom 		= state0.zoom 	- state1.zoom

	dir 		= state0.position - state1.lookat

	right 		= unit(cross(dir, state1.up))
	xrotation 	= rotate2(deg2rad(xangle), state1.up) #rotation matrix around up
	yrotation 	= rotate2(deg2rad(yangle), right)
	zoomdir		= unit(dir)*zoom #zoom just shortens the direction vector

 	pos1 		= Vector3(yrotation * xrotation * [(state0.position-zoomdir)...])

 	Rotatable(pos1, state1.lookat, state1.up, state1.xangle, state1.yangle, state1.zoom)
end
function rotate2{T}(angle::T, axis::Vector3{T})
 	rotationmatrix(qrotation(convert(Array, axis), angle))
end