WorldViz User Forum - how to write the interface code

WorldViz User Forum (https://forum.worldviz.com/index.php)

- Vizard (https://forum.worldviz.com/forumdisplay.php?f=17)

- - how to write the interface code (https://forum.worldviz.com/showthread.php?t=2021)

how to write the interface code

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

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:

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()

how to move the other part

Code:

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?

For your elif block:

if link is not none: remove link

Better. Replace elif with if.

Code:

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)

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

Code:

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.

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?

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.

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

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

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..

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...

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

Code:

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?

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.

Code:

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...

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

Code:

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)

how to achieve the stereoscopic vision

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