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  #1  
Old 05-11-2009, 09:39 AM
Penguin Penguin is offline
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Join Date: Mar 2009
Posts: 14
rotating an object

Hi, I want to rotate an object (sphere) similar to the globe in google earth.

The sphere is mapped in front of the main view. With the use of the viz.pick() command I get the intersection position of the mouse pointer on the sphere (intersectionItem.point).

The following code is running in a mouse button down callback function. While dragging the mouse over the sphere the new intersection position is callculated (curIntersectionItem.point)

With this two points and the center of the sphere I get two direction vectors and the angle inbetween.

The rotation of the sphere seems to work until it rolls. Then the mouse movement does not match to the rotation of the sphere any more!

Is there a better way to achieve a stable rotation? While dragging in google earth the same part of the globe always stays under the mouse pointer.

Code:
curIntersectionItem = calcUiIntersection()
rotationMat = vizmat.Transform()
rotationMat.makeVecRotVec(vizmat.VectorToPoint(sphere.getPosition(viz.ABS_GLOBAL),intersectionItem.point),vizmat.VectorToPoint(sphere.getPosition(viz.ABS_GLOBAL),curIntersectionItem.point))

spherePos = sphere.getPosition(viz.ABS_GLOBAL)
sphereMat = sphere.getMatrix(viz.ABS_GLOBAL)
sphereMat.setTrans(0,0,0)

transformMat = vizmat.Transform()
transformMat = rotationMat * sphereMat

transformMat.setTrans(spherePos)
sphere.setMatrix(transformMat,viz.ABS_GLOBAL)

intersectionItem = curIntersectionItem
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  #2  
Old 05-11-2009, 04:32 PM
Gladsomebeast Gladsomebeast is offline
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Join Date: Mar 2005
Location: Isla Vizta, CA
Posts: 397
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?

Code:
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)
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WorldViz LLC
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  #3  
Old 05-12-2009, 11:21 AM
Penguin Penguin is offline
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Join Date: Mar 2009
Posts: 14
Except for the slight roll, your code works fine. But here it comes: when I attach the sphere to the main view the rotation doesn't work any longer.

Code:
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'))

viewLink = viz.link(viz.MainView,node)
viewLink.preTrans([0,0,3])

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)
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  #4  
Old 05-12-2009, 11:29 AM
Gladsomebeast Gladsomebeast is offline
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Join Date: Mar 2005
Location: Isla Vizta, CA
Posts: 397
Righto. The link is overriding the rotation we are giving the sphere. To fix we tell the link to only operate on position

Code:
viewLink = viz.link(viz.MainView,node, mask=viz.LINK_POS)
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WorldViz LLC
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  #5  
Old 05-12-2009, 01:09 PM
Penguin Penguin is offline
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Join Date: Mar 2009
Posts: 14
Step by step I'm able to locate the source of the problem: I use the sphere in a hierarchical group order. The following code reproduces the strange behaviour of rotating.

Code:
import viz
import vizmat
import vizshape

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

root = viz.add(viz.GROUP, parent=viz.WORLD)
root.setPosition([0,1.8,3],viz.REL_GLOBAL)

node = vizshape.addSphere(pos=[0,0,0], parent=root)
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)
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  #6  
Old 05-13-2009, 10:18 AM
Jerry Jerry is offline
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Join Date: Jun 2004
Posts: 105
Here's another way to do it.

Code:
from viz import *

go()

clearcolor(.8,.8,.8)
vert = add('ball.wrl')
vert.translate(0,1.8,2)

xang = 0
yang = 0
INCREMENT = .5

mouse(OFF)
restrictmouse(OFF)

def mousemove(x,y):					
	global xang,yang
	
	state = buttonstate()

	if state == MOUSEBUTTON_LEFT:
		xang = xang + x*INCREMENT
		yang = yang + y*INCREMENT
		vert.rotate(0,1,0,-x*INCREMENT,RELATIVE_WORLD)
		vert.rotate(1,0,0,y*INCREMENT,RELATIVE_WORLD)
		
mousedata(RELATIVE,RELATIVE)
callback(MOUSEMOVE_EVENT,mousemove)
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  #7  
Old 05-13-2009, 12:15 PM
Gladsomebeast Gladsomebeast is offline
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Join Date: Mar 2005
Location: Isla Vizta, CA
Posts: 397
Interesting... I shall dub thee Spinner Metaphor Method and place you in a file of honor.
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WorldViz LLC
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  #8  
Old 05-14-2009, 09:25 AM
Penguin Penguin is offline
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Join Date: Mar 2009
Posts: 14
Hi Gladsomebeast, the effect of slight roll results in the lookat call. The second argument is a optional roll value. The internal value of viz.ABS_GLOBAL is 4:

Code:
node.lookat(intersectionItem.point, 0, viz.ABS_GLOBAL)
not

Code:
node.lookat(intersectionItem.point,viz.ABS_GLOBAL)
because this is a roll of 4 degree

Code:
node.lookat(intersectionItem.point,4)
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  #9  
Old 05-14-2009, 10:50 AM
Gladsomebeast Gladsomebeast is offline
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Join Date: Mar 2005
Location: Isla Vizta, CA
Posts: 397
Of course, of course, the roll parameter =) Thanks for sharing the fix.
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WorldViz LLC
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  #10  
Old 05-17-2009, 12:47 PM
Jerry Jerry is offline
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Join Date: Jun 2004
Posts: 105
Since spinning balls is so much fun,
Let's try spinning more than one.

Code:
from viz import *

go()

clearcolor(.8,.8,.8)
ball1 = add('ball.wrl')
ball1.translate(.3,1.8,1.5)
ball2 = add('ball.wrl')
ball2.translate(-.3,1.8,1.5)

balls = []
balls.append(ball1)
balls.append(ball2)

INCREMENT = .5

mouse(OFF)
restrictmouse(OFF)

def mousemove(x,y):					
	
	object = pick() 

	if viz.mouse.getState() == viz.MOUSEBUTTON_LEFT:
		mousedown = 1
	else:
		mousedown = 0
		
	if object in balls and mousedown == 1:
		object.rotate(0,1,0,-x*INCREMENT,RELATIVE_WORLD)
		object.rotate(1,0,0,y*INCREMENT,RELATIVE_WORLD)

		
mousedata(RELATIVE,RELATIVE)
callback(MOUSEMOVE_EVENT,mousemove)

Or if you like the number three,
Let's try to make them all agree.

Code:
from viz import *

go()

clearcolor(.8,.8,.8)
ball1 = add('ball.wrl')
ball1.translate(0,2.1,2)
ball2 = add('ball.wrl')
ball2.translate(.4,1.5,2)
ball3 = add('ball.wrl')
ball3.translate(-.4,1.5,2)

balls = []
balls.append(ball1)
balls.append(ball2)
balls.append(ball3)

INCREMENT = .5

mouse(OFF)
restrictmouse(OFF)

def mousemove(x,y):					
	
	object = pick() 

	if viz.mouse.getState() == viz.MOUSEBUTTON_LEFT:
		mousedown = 1
	else:
		mousedown = 0
		
	if object in balls and mousedown == 1:
		for b in range(len(balls)):
			balls[b].rotate(0,1,0,-x*INCREMENT,RELATIVE_WORLD)
			balls[b].rotate(1,0,0,y*INCREMENT,RELATIVE_WORLD)

		
mousedata(RELATIVE,RELATIVE)
callback(MOUSEMOVE_EVENT,mousemove)

And here's the one you want the most,
Just like iPhone make it coast.

Code:
from viz import *

go()

clearcolor(.8,.8,.8)
ball1 = add('ball.wrl')
ball1.translate(.3,1.8,1.5)
ball2 = add('ball.wrl')
ball2.translate(-.3,1.8,1.5)

balls = []
balls.append(ball1)
balls.append(ball2)

increment = .5
COAST = 1
mx = 0
my = 0
object = []
spinning = 0

mouse(OFF)
restrictmouse(OFF)

def mousemove(x,y):					
	global mx,my,object,spinning,increment
	
	if spinning == 0:
		object = pick() 

	if mouse.getState() == MOUSEBUTTON_LEFT:
		object = pick() 
		mousedown = 1
		killtimer(COAST)
		spinning = 0
	else:
		mousedown = 0
		
	if object in balls and mousedown == 1:
		object.rotate(0,1,0,-x*increment,RELATIVE_WORLD)
		object.rotate(1,0,0,y*increment,RELATIVE_WORLD)
		mx = x
		my = y

	if mousedown == 1 and spinning == 0:
		increment = .5
		spinning = 1
		starttimer(COAST,.01,FOREVER)
		
mousedata(RELATIVE,RELATIVE)
callback(MOUSEMOVE_EVENT,mousemove)

def onTimer(num):
	global spinning,mx,my,object,increment
	
	if num == COAST:
	
		object.rotate(0,1,0,-mx*increment,RELATIVE_WORLD)
		object.rotate(1,0,0,my*increment,RELATIVE_WORLD)

		increment = increment - .01
		if abs(increment) < .01:
			spinning = 0
			increment = .5
			killtimer(COAST)
						
viz.callback(viz.TIMER_EVENT,onTimer)
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  #11  
Old 05-18-2009, 05:24 PM
Gladsomebeast Gladsomebeast is offline
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Join Date: Mar 2005
Location: Isla Vizta, CA
Posts: 397
Spinning is fun
I do agree.
But rotations be done,
I'm going crazy.
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WorldViz LLC
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