WorldViz User Forum - Drawing trajectory of an object

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Drawing trajectory of an object

It is possible to attach the pencil tool to an object and draw its trajectory?

Or there is a better way to do that??

I'm doing a robot kinematic simulator and I want to display the end effector trajectory

Yes, you can link the pencil tool to any object. You could either activate the pencil draw command with an input signal (mouse button, keypress, etc.) or have it draw continuously.

Hi Jeff, thank you for your answer

Could you please show me an example of a pencil attached to an object and drawing continuosly? Because I can't make it work properly

Take a look at the pencil documentation for commands available. The following example script executes the draw command continuously:

Code:

"""  

Right mouse button clears the drawing.  

Middle mouse button changes color.  

Mouse movements control viewpoint orientation.  

Arrow Keys control viewpoint position.  

""" 



import viz

import vizshape

import vizinfo

vizinfo.InfoPanel(align=viz.ALIGN_LEFT_BOTTOM)



viz.setMultiSample(4)

viz.fov(60)

viz.go()



piazza = viz.add('piazza.osgb')

arrow = vizshape.addArrow(length=0.2, color = viz.RED)



from tools import pencil

tool = pencil.Pencil()



# update code for pencil

def update(tool):



        state = viz.mouse.getState()

        if state & viz.MOUSEBUTTON_RIGHT:

                tool.clear()

        elif state & viz.MOUSEBUTTON_MIDDLE:

                tool.cycleColor()

        else:

                tool.draw()



tool.setUpdateFunction(update)



#Link the pencil tool to an arrow  

#Then move the arrow in the reference frame of the viewpoint

from vizconnect.util import virtual_trackers

mouseTracker = virtual_trackers.ScrollWheel(followMouse = True)

mouseTracker.distance = 1

arrowLink = viz.link(mouseTracker,arrow)

arrowLink.postMultLinkable(viz.MainView)

viz.link(arrowLink,tool)



import vizcam

vizcam.FlyNavigate()



#Hide the mouse cursor

viz.mouse.setVisible(viz.OFF)

Thank you Jeff, but what I can't do is to attach the pencil to an osgb object (in this case the robot end effector), how can I do that?

Thank you in advance

Could you please help me to attach the pencil tool to an osgb object?

Have you tried to modify the pencil example code like this:

Code:

robot=viz.add('your_robot_name.osgb')

...

arrowLink = viz.link(mouseTracker,robot)

I've tried it , but if you add mousetracker , I end up drawing with the mouse.

What I want is to attach the pencil to the end of the robot and the pencil draw the trajectory of the robot end effector

You can parent or link the pencil tool to any node in Vizard.