how to write the interface code

[nasr]

hello all,

my university got a virtual reality suite which consists of a projector, a transluscent screen, amx controller, intersense 900 inertial ultra sonic motion tracking system, wand and head trackers. i will import a catia based 3d model in vizard. could some body please tell me how can i navigate with the wand and head tracker in my application. how to write the interface code? are there any ebooks available on the vizard site?

thankyou...

with regards
Nasr

[Gladsomebeast]

To support multiple hardware interfaces, like a keyboard+mouse test mode and production VR tracker mode, you want to separate the "application logic" from the hardware interface code. Their are a few ways you can organize the code to do this. I would use object oriented classes.

Say the user interacts with your Catia model with some 3D cursor thing. That is application logic. I'ed create a Cursor class that holds all the application level information and behavior for this 3D cursor: 3D position, appearance, methods for selecting and moving the Catia model.

I'd create another class called CursorControllerKeyboard that has a pointer to the Cursor class. This guy will respond to keyboard events and manipulate the Cursor appropratly. Another class called CursorControllerWand could manipulate the Cursor in response to input from the Intersense Wand device.

Let the Cursor classes constructor choose which controler to create based on some configuration varable. Here's some code:

import viz
import vizact

IS_VR_HARDWARE_CONNECTED = False

class Cursor:
	def __init__(self):
		#Application level stuff
		self.root = viz.addGroup() #3d position
		self.model = viz.add('arrow.wrl', parent=self.root)
		
		if IS_VR_HARDWARE_CONNECTED:
			self.CursorControllerWand(self) #pass pointer to self
		else:
			self.CursorControllerKeyboard(self) #pass pointer to self
		
	def grabModel(self):
		#application level stuff
		self.model.color(viz.GREEN)
		
	class CursorControllerKeyboard: #sub-class of Cursor, only Cursor can use me
		def __init__(self, appCursor):
			self.appCursor = appCursor
			vizact.onkeydown(viz.KEY_UP, self.appCursor.root.setPosition, [0,0,1], viz.REL_LOCAL)
			vizact.onkeydown(' ', self.appCursor.grabModel)
			
			
	class CursorControllerWand: #sub-class of Cursor, only Cursor can use me
		def __init__(self, appCursor):
			self.appCursor = appCursor
			#do Vr hardware callbacks
			
if __name__ == '__main__':
	viz.go()
	Cursor()

[nasr]

def toggleLink():
	global link
	if link:
		#If link exits, stop grabbing
		link.remove()
		link = None

	elif vizmat.Distance(hand.getPosition(), ball.getPosition()) < .5:
		link = viz.grab( hand, ball )

vizact.onpick(ball,toggleLink)

with this code i am able to one component using the marker. i have included one more component.. when i am trying to pick the other component the first component is also moving how to disable the link between the market and first component?

[Gladsomebeast]

For your elif block:

if link is not none: remove link

[Gladsomebeast]

Better. Replace elif with if.

def toggleLink():
	global link
	if link:
		#If link exits, stop grabbing
		link.remove()
		link = None

	if vizmat.Distance(hand.getPosition(), ball.getPosition()) < .5:
		link = viz.grab( hand, ball )

vizact.onpick(ball,toggleLink)

[nasr]

paul thank you very much for your reply.this is my full program

import viz

viz.go()

viz.MainView.setPosition(0,1.5,-4)
import viztracker
tracker = viztracker.MousePos()
myroom=viz.add('room.wrl')
#Add the object that will do the grabbing and link it to the tracker
hand = viz.add('marker.wrl')
viz.link(tracker, hand)

#turn off mouse navigation
viz.mouse(viz.OFF)

#Add the object that the marker will grab
ball = viz.add( 'ball.wrl' )

ball.translate( 0.5, 1.5, 3 )
table=viz.add('table.wrl')
link = None
#Grab or let go of the ball

def toggleLink():
	global link
	if link:
		#If link exits, stop grabbing
		link.remove()
		link = None
         elif vizmat.Distance(hand.getPosition(), ball.getPosition()) < .5:
		vizact.onpick(ball,toggleLink)

now i want to move the ball and the table seperately. now could you please tell me how to make the changes.

[nasr]

vizmat.Distance(hand.getPosition(), ball.getPosition()) < .5: link = viz.grab( hand, ball )

vizact.onpick(ball,toggleLink)
paul

in the above code im able to grab the ball only. if im trying this loop with an if condition, after selecting the ball im not able to stop the ball how to change the code?

[Gladsomebeast]

My last post from yesterday will fix your problem. Notice how I changed the elif to if in the toggleLink function.

Also, you will want to call toggleLink whenever the mouse button is pressed, so replace vizact.onpick with vizact.onmousebutton.

[nasr]

paul thanks for your quick reply... if i want to rotate the object how can i do it?

[Gladsomebeast]

Because of the grab link, rotating the hand will rotate the object. Use whatever keyboard/mouse keys you want.

[nasr]

paul thankyou very much for your suggestions...could you tell the code for rotating the ball using the mouse...i dont have any idea how to do it...just give me the clue...

thankyou..

[nasr]

hello paul...i tried rotating the object using the keyboard..by assigning keys for each axis....but i want to do this using mouse in order to reduce the number of lines of code...could u please tell me the function for that. how it could be done? i wil be waiting for ur reply..thankyou...

[Gladsomebeast]

How about rotating an object when you hold down the right mouse button. You could use Jerry's code from this post to rotate the object after it is selected: http://forum.worldviz.com/showthread.php?t=2022

[nasr]

def toggleLink():
	global link
	if link:
		#If link exits, stop grabbing
		link.remove()
		link = None

	if vizmat.Distance(hand.getPosition(), ball.getPosition()) < .5:
		link = viz.grab( hand, ball )
	if vizmat.Distance(hand.getPosition(),crank.getPosition()) < .5:
		link=viz.grab ( hand, crank)

vizact.onmousedown(' ' ,toggleLink())

i wrote this code for grabbing the first object and then releasing it and then trying to hold the second object..but its not working...paul can u tell me where is the problem?

[Gladsomebeast]

The vizact.onmousedown(' ' ,toggleLink()) needs a mouse button argument. Check docs on this.

Otherwise I don't see whats wrong. Throw some print statements around to see where the code is going or not going.

You also have the possibility of creating two links and loosing your handle to the first link. To fix create a list of grabable objects and use a "for in" loop to check if the hand should grab. If you grab, end the loop with a "break" statement.

[nasr]

def toggleLink():
	global link
	if link:
		#If link exits, stop grabbing
		link.remove()
		link = None

	if vizmat.Distance(hand.getPosition(), ball.getPosition()) < .5:
		link = viz.grab( hand, ball )
	if vizmat.Distance(hand.getPosition(),crank.getPosition()) < .5:
		link=viz.grab ( hand, crank)

vizact.onpick(viz.MOUSEBUTTON_RIGHT ,toggleLink)

paul im trying with this mouse event..but still not able to select any one object at this time...

[nasr]

sorry i tried with this code also...but not working

def toggleLink():
	global link
	if link:
		#If link exits, stop grabbing
		link.remove()
		link = None

	if vizmat.Distance(hand.getPosition(), ball.getPosition()) < .5:
		link = viz.grab( hand, ball )
	if vizmat.Distance(hand.getPosition(),crank.getPosition()) < .5:
		link=viz.grab ( hand, crank)

vizact.onmousedown(viz.MOUSEBUTTON_RIGHT ,toggleLink)

[nasr]

how to enable the stereoscopic vision in a simple vizard application....