[Gladsomebeast]

Interesting goal. I whipped up a bit of code that orbits the sphere by telling the sphere to "lookat" the intersection point, then rotating the sphere the initial offset amount.

The code is not quite right yet because sustained clicking on the same point rolls the sphere around that point. Maybe somebody knows whats wrong?

import viz
import vizmat
import vizshape

viz.go()
viz.mouse.setOverride(viz.ON)

node = vizshape.addSphere(pos=[0, 1.8, 3])
node.texture(viz.add('image2.jpg'))
rotation = None
def onGrab():
	global rotation
	intersectionItem = viz.pick(1)
	if intersectionItem.valid:
		src_ori = vizmat.Quat(node.getQuat(viz.ABS_GLOBAL))
		node.lookat(intersectionItem.point, viz.ABS_GLOBAL)
		dst_ori = vizmat.Quat(node.getQuat(viz.ABS_GLOBAL))
		#D = O * S so O = D * 1/S
		rotation =  src_ori * dst_ori.inverse()
		
vizact.onmousedown(viz.MOUSEBUTTON_LEFT, onGrab)

def moveSphere():
	if rotation:
		intersectionItem = viz.pick(1)
		if intersectionItem.valid:
			node.lookat(intersectionItem.point)
			node.setQuat(rotation, viz.ABS_LOCAL)
		
vizact.onupdate(viz.PRIORITY_DEFAULT, moveSphere)
		
def endGrab():
	global rotation
	rotation = None
vizact.onmouseup(viz.MOUSEBUTTON_LEFT, endGrab)