Drawing trajectory of an object

[Daniel]

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

[Jeff]

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.

[Daniel]

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

[Jeff]

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

"""  
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)

[Daniel]

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

[Daniel]

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

[Samuli]

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

robot=viz.add('your_robot_name.osgb')
...
arrowLink = viz.link(mouseTracker,robot)

[Daniel]

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

[Jeff]

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