[Andy]

Hey,
has somebody an idea how to create an realistic telescopic cylinder?
I would like to create a platform for lifting persons but I have problems to create the telescopic arm of this platform.

I have created an example of my problem. I use the joints of the opal physical engine. There are very useful but instable in this case. I need a realistically behaviour of the physic and also a collision detection with my environment, so that I see no other way as using the opal engine.

Can somebody help me?
thanks andy

import viz
import vizact
import vizinfo

PHYSICS_SIM_TIMER = 2

viz.go()

viz.phys.enable()
viz.clearcolor(viz.SKYBLUE)
viz.MainView.setPosition(0,1.5,-10)

#environment
###########
info = vizinfo.add('use up/down/leftr/right for control \n r for reset')
info.translate( .35, .1 )
info.scale(0.7, 0.7)

ground = viz.add( 'tut_ground.wrl' )
ground.collidePlane() #Make ground collide with objects as if it were an infinite plane

#some gui elements for parametrize the material characteristics
###############################################################
obj1Info = vizinfo.add( 'Center Material Characteristics' )
obj1Info.translate( .35, .96 )
obj1Info.scale(0.7, 0.7)
obj1Density = obj1Info.add( viz.SLIDER, 'Density' )
obj1Friction = obj1Info.add( viz.SLIDER, 'Friction' )
obj1Hardness = obj1Info.add( viz.SLIDER, 'Hardness' )
obj1Bounce = obj1Info.add( viz.SLIDER, 'Bounce' )
#Initial material settings
obj1Density.set( 1 )
obj1Friction.set( .001 )
obj1Hardness.set( 1 )
obj1Bounce.set( 0 )

obj2Info = vizinfo.add( 'Tube1 Material Characteristics' )
obj2Info.translate( .62, .96 )
obj2Info.scale(0.7, 0.7)
obj2Density = obj2Info.add( viz.SLIDER, 'Density' )
obj2Friction = obj2Info.add( viz.SLIDER, 'Friction' )
obj2Hardness = obj2Info.add( viz.SLIDER, 'Hardness' )
obj2Bounce = obj2Info.add( viz.SLIDER, 'Bounce' )
#Initial material settings
obj2Density.set( .3 )
obj2Friction.set( .001 )
obj2Hardness.set( 1 )
obj2Bounce.set( 0 )

#Interface to change ball characteristics
obj3Info = vizinfo.add( 'Tube2 Material Characteristics' )
obj3Info.translate( .9, .96 )
obj3Info.scale(0.7, 0.7)
obj3Density = obj3Info.add( viz.SLIDER, 'Density' )
obj3Friction = obj3Info.add( viz.SLIDER, 'Friction' )
obj3Hardness = obj3Info.add( viz.SLIDER, 'Hardness' )
obj3Bounce = obj3Info.add( viz.SLIDER, 'Bounce' )
#Initial material settings
obj3Density.set( .3 )
obj3Friction.set( .001 )
obj3Hardness.set( 1 )
obj3Bounce.set( 0 )

#telescopic cylinder platform
##############################
center = viz.add('box.wrl', scale=[1,2,1], pos=[2,1.2,0], color=viz.BLUE)
centerCollideBox = center.collideBox(density=obj1Density.get(), friction=obj1Friction.get(),hardness=obj1Hardness.get(), bounce=obj1Bounce.get())

tupe1Pos = [0,2,0]
tupe1AxisLimit = [-10,60]
tube1 = viz.add('box.wrl', scale=[4,0.2,0.2], pos=tupe1Pos, color=viz.YELLOW)
tube1CollideBox = tube1.collideBox(density=obj2Density.get(), friction=obj2Friction.get(),hardness=obj2Hardness.get(), bounce=obj2Bounce.get())

upDownAngle = 0
tube1Joint = viz.phys.addHingeJoint(center, tube1, pos=[tupe1Pos[0]+2,tupe1Pos[1],tupe1Pos[2]], axis0=[0,0,1]) 

tube2Pos = [-0.5,2,0]
tube2InOutLimit = [0.2,3]
tube2 = viz.add('box.wrl', scale=[4,0.15,0.15], pos=tube2Pos, color=viz.GREEN)
tube2CollideBox = tube2.collideBox(density=obj3Density.get(), friction=obj3Friction.get(), hardness=obj3Hardness.get(), bounce=obj3Bounce.get())

inOutPos = 0
tube2Joint = viz.phys.addSliderJoint(tube1, tube2,pos=[tube2Pos[0], tube2Pos[1], tube2Pos[2]],axis0=(1,0,0))


def applyPhysics():
	global upDownAngle, inOutPos
	
	if upDownAngle > tupe1AxisLimit[1]:
		upDownAngle = tupe1AxisLimit[1]
	elif upDownAngle < tupe1AxisLimit[0]:
		upDownAngle = tupe1AxisLimit[0]
	
	if inOutPos > tube2InOutLimit[1]:
		inOutPos = tube2InOutLimit[1]
	elif inOutPos < tube2InOutLimit[0]:
		inOutPos = tube2InOutLimit[0]
	
	#apply phys for UpDown-tube
	print 'current upDown-angle: ', upDownAngle
	print 'current inOut-position: ', inOutPos
	tube1Joint.setMotorAngle(0, upDownAngle,0xFF,0.3)
	tube2Joint.setMotorAngle(0, inOutPos,0xFF,0.8)

def update(num):
	if num == PHYSICS_SIM_TIMER:
		applyPhysics()
viz.callback(viz.TIMER_EVENT, update)

def reset():
	global upDownAngle, inOutPos
	upDownAngle = 0
	inOutPos = 0
	center.reset()
	tube1Joint.reset()
	tube2Joint.reset()

def mykeyboard(key):
	global upDownAngle, inOutPos
	if key == viz.KEY_UP:
		upDownAngle = upDownAngle + (viz.elapsed()* 10.0)
	if key == viz.KEY_DOWN:
		upDownAngle = upDownAngle - (viz.elapsed()* 10.0)
	if key == viz.KEY_LEFT:
		inOutPos = inOutPos + (viz.elapsed()* 10.0)
	if key == viz.KEY_RIGHT:
		inOutPos = inOutPos - (viz.elapsed()* 10.0)
	
	if key == 'r':
		reset()
viz.callback(viz.KEYBOARD_EVENT, mykeyboard)

def onSlider(obj,pos):
	if obj1Density.get() > 0:
		centerCollideBox.setDensity(obj1Density.get())
	centerCollideBox.setFriction(obj1Friction.get())
	centerCollideBox.setHardness(obj1Hardness.get())
	centerCollideBox.setBounce(obj1Bounce.get())
	
	if obj2Density.get() > 0:
		tube1CollideBox.setDensity(obj2Density.get())
	tube1CollideBox.setFriction(obj2Friction.get())
	tube1CollideBox.setHardness(obj2Hardness.get())
	tube1CollideBox.setBounce(obj2Bounce.get())
	
	if obj3Density.get() > 0:
		tube2CollideBox.setDensity(obj3Density.get())
	tube2CollideBox.setFriction(obj3Friction.get())
	tube2CollideBox.setHardness(obj3Hardness.get())
	tube2CollideBox.setBounce(obj3Bounce.get())
viz.callback(viz.SLIDER_EVENT,onSlider) 

viz.starttimer(PHYSICS_SIM_TIMER, .01, viz.FOREVER)