Pick action through exposing joints not working


I am trying to implement the pick action for my character. I found a sample file called looking-and-gripping tutorial in the samples directory downloaded with panda.
All I did was change Ralph to my model. When I print the parent of the object(tea pot -banana or sword), I find that it is the right hand as I specified in the code, but no object gets rendered to the screen. I cannot figure out the source of the problem. is there a mistake in code or is there something I have to edit in the egg file.

#!/usr/bin/env python

# Author: Shao Zhang and Phil Saltzman
# Models and Textures by: Shaun Budhram, Will Houng, and David Tucker
# Last Updated: 2015-03-13
# This tutorial will cover exposing joints and manipulating them. Specifically,
# we will take control of the neck joint of a humanoid character and rotate that
# joint to always face the mouse cursor.  This will in turn make the head of the
# character "look" at the mouse cursor.  We will also expose the hand joint and
# use it as a point to "attach" objects that the character can hold.  By
# parenting an object to a hand joint, the object will stay in the character's
# hand even if the hand is moving through an animation.

from direct.showbase.ShowBase import ShowBase
from panda3d.core import AmbientLight, DirectionalLight
from panda3d.core import TextNode, NodePath, LightAttrib
from panda3d.core import LVector3
from direct.actor.Actor import Actor
from direct.task.Task import Task
from direct.gui.OnscreenText import OnscreenText
from direct.showbase.DirectObject import DirectObject
import sys

# A simple function to make sure a value is in a given range, -1 to 1 by
# default
def clamp(i, mn=-1, mx=1):
    return min(max(i, mn), mx)

# Macro-like function used to reduce the amount to code needed to create the
# on screen instructions
def genLabelText(text, i):
    return OnscreenText(text=text, parent=base.a2dTopLeft, scale=.06,
                        pos=(0.06, -.08 * i), fg=(1, 1, 1, 1),
                        shadow=(0, 0, 0, .5), align=TextNode.ALeft)

class LookingGrippingDemo(ShowBase):

    def __init__(self):
        # Initialize the ShowBase class from which we inherit, which will
        # create a window and set up everything we need for rendering into it.

        # This code puts the standard title and instruction text on screen
        self.title = OnscreenText(text="Panda3D: Tutorial - Joint Manipulation",
                                  fg=(1, 1, 1, 1), parent=base.a2dBottomRight,
                                  align=TextNode.ARight, pos=(-0.1, 0.1),
                                  shadow=(0, 0, 0, .5), scale=.08)

        self.onekeyText = genLabelText("ESC: Quit", 1)
        self.onekeyText = genLabelText("[1]: Teapot", 2)
        self.twokeyText = genLabelText("[2]: Candy cane", 3)
        self.threekeyText = genLabelText("[3]: Banana", 4)
        self.fourkeyText = genLabelText("[4]: Sword", 5)

        # Set up key input
        self.accept('escape', sys.exit)
        self.accept('1', self.switchObject, [0])
        self.accept('2', self.switchObject, [1])
        self.accept('3', self.switchObject, [2])
        self.accept('4', self.switchObject, [3])

        base.disableMouse()  # Disable mouse-based camera-control
        self.camera.setPos(0, -15, 2)  # Position the camera

        # self.eve = Actor("models/eve",  # Load our animated charachter
        #                  {'walk': "models/eve_walk"})
        self.eve = Actor("models/boy3/jack",  # Load our animated charachter
                         {'walk': "models/boy3/jack_walk-Armature|mixamo.com|Layer0.007.egg"})
        self.eve.reparentTo(self.render)  # Put it in the scene

        # Now we use controlJoint to get a NodePath that's in control of her neck
        # This must be done before any animations are played
        self.eveNeck = self.eve.controlJoint(None, 'modelRoot', 'Neck')
        print("eve Neck",self.eveNeck)

        # We now play an animation. An animation must be played, or at least posed
        # for the nodepath we just got from controlJoint to actually effect the
        # model
        self.eve.actorInterval("walk", playRate=2).loop()

        # Now we add a task that will take care of turning the head
        self.taskMgr.add(self.turnHead, "turnHead")

        # Now we will expose the joint the hand joint. ExposeJoint allows us to
        # get the position of a joint while it is animating. This is different than
        # controlJonit which stops that joint from animating but lets us move it.
        # This is particularly usefull for putting an object (like a weapon) in an
        # actor's hand
        self.rightHand = self.eve.exposeJoint(None, 'modelRoot', 'RightHand')
        # This is a table with models, positions, rotations, and scales of objects to
        # be attached to our exposed joint. These are stock models and so they needed
        # to be repositioned to look right.
        positions = [("teapot", (0, -.66, -.95), (90, 0, 90), .4),
                     ("models/candycane", (.15, -.99, -.22), (90, 0, 90), 1),
                     ("models/banana", (.08, -.1, .09), (0, -90, 0), 1.75),
                     ("models/sword", (.11, .19, .06), (0, 0, 90), 1)]

        self.models = []  # A list that will store our models objects
        for row in positions:
            np = self.loader.loadModel(row[0])  # Load the model
            np.setPos(row[1][0], row[1][1], row[1][2])  # Position it
            np.setHpr(row[2][0], row[2][1], row[2][2])  # Rotate it
            np.setScale(row[3])  # Scale it
            # Reparent the model to the exposed joint. That way when the joint moves,
            # the model we just loaded will move with it.

            self.models.append(np)  # Add it to our models list

        self.switchObject(0)  # Make object 0 the first shown
        self.setupLights()  # Put in some default lighting

    # This is what we use to change which object it being held. It just hides all of
    # the objects and then unhides the one that was selected
    def switchObject(self, i):
        for np in self.models:

    # This task gets the position of mouse each frame, and rotates the neck based
    # on it.
    def turnHead(self, task):
        # Check to make sure the mouse is readable

        if base.mouseWatcherNode.hasMouse():

            # get the mouse position as a LVector2. The values for each axis are from -1 to
            # 1. The top-left is (-1,-1), the bottom right is (1,1)
            mpos = base.mouseWatcherNode.getMouse()
            # Here we multiply the values to get the amount of degrees to turn
            # Restrain is used to make sure the values returned by getMouse are in the
            # valid range. If this particular model were to turn more than this,
            # significant tearing would be visable
            self.eveNeck.setP(clamp(mpos.getX()) * 50)
            self.eveNeck.setH(clamp(mpos.getY()) * 20)

        return Task.cont  # Task continues infinitely

    def setupLights(self):  # Sets up some default lighting
        ambientLight = AmbientLight("ambientLight")
        ambientLight.setColor((.4, .4, .35, 1))
        directionalLight = DirectionalLight("directionalLight")
        directionalLight.setDirection(LVector3(0, 8, -2.5))
        directionalLight.setColor((0.9, 0.8, 0.9, 1))

demo = LookingGrippingDemo()  # Create an instance of our class
demo.run()  # Run the simulation

Here are the links of the model and the walk animation egg files that I am using.


If you call self.eve.listJoints(), you’ll see something like this:

     Hips  scale 0.01 hpr -180 90 -180 trans 0 -0.0255094 0.832081
       BoyFacialAnim_Joint  trans 1 -82.2081 -1.55092
                   RightHand  trans -22.9929 -7.62939e-06 -0.870901
                     RightHandIndex1  trans -11.3725 0.0650253 3.69915

What’s notable is that the hips, which are a parent of the right hand, have a scale of 0.01. This scale also will apply to any child nodes.

So, your models are appearing, they are just appearing really small. If I change the scale of the sword to 40, it does appear:


That was a subtle one. Thank you for pointing it out. Is there a way in panda so that I can fix the scale??I mean that I want the scale to be kept as it is. I don’t want the scale of the model to be changed when parenting it to the hand


I don’t know if there is an easy way to fix the scale in the model and animation other than fixing it in the modelling tool and then re-exporting it.

You could work around it in Panda, though. You could first set the scale, then do wrtReparentTo instead of reparentTo, and then set the position and hpr. Though, this might have other side-effects, I’m not sure.

Or, you could use a CompassEffect to ensure that the node’s scale is always relative to a specified reference node (by default, the root of the scene graph):

np.setEffect(CompassEffect.make(NodePath(), CompassEffect.P_scale))

Or you could just obtain the scale of the joint relative to the root programmatically and divide your scale by that:

np.setScale(row[3] / self.rightHand.getScale(self.eve)[0])