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Penguin
05-11-2009, 09:39 AM
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.


curIntersectionItem = calcUiIntersection()
rotationMat = vizmat.Transform()
rotationMat.makeVecRotVec(vizmat.VectorToPoint(sph ere.getPosition(viz.ABS_GLOBAL),intersectionItem.p oint),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

Gladsomebeast
05-11-2009, 04:32 PM
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)

Penguin
05-12-2009, 11:21 AM
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.


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)

Gladsomebeast
05-12-2009, 11:29 AM
Righto. The link is overriding the rotation we are giving the sphere. To fix we tell the link to only operate on position

viewLink = viz.link(viz.MainView,node, mask=viz.LINK_POS)

Penguin
05-12-2009, 01:09 PM
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.


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)

Jerry
05-13-2009, 10:18 AM
Here's another way to do it.



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)

Gladsomebeast
05-13-2009, 12:15 PM
Interesting... I shall dub thee Spinner Metaphor Method and place you in a file of honor.

Penguin
05-14-2009, 09:25 AM
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:


node.lookat(intersectionItem.point, 0, viz.ABS_GLOBAL)


not


node.lookat(intersectionItem.point,viz.ABS_GLOBAL)


because this is a roll of 4 degree


node.lookat(intersectionItem.point,4)

Gladsomebeast
05-14-2009, 10:50 AM
Of course, of course, the roll parameter =) Thanks for sharing the fix.

Jerry
05-17-2009, 12:47 PM
Since spinning balls is so much fun,
Let's try spinning more than one.


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.


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.


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)

Gladsomebeast
05-18-2009, 05:24 PM
Spinning is fun
I do agree.
But rotations be done,
I'm going crazy.