visualise Actor bones (skeleton)?

Scripting Issues
1

Im wondering if theres a function to show a visual representation of bones, like the ones for visualising collision geometry.
Im not very familiar in this field, so I dont know if egg even stores actual bone data, as I think ragdolls arent possible with this format.

2

You could simply iterate over the joints in the hierarchy and reparent a sphere to every one of them. I use that approach for visualising ragdolls.

If you want to draw the bones, I suppose you could draw a cylinder node for every parent<>child relationship.

3

I guess this means there isnt a built-in function for this.
Small problem, how can I set the visual ‘bone’s’ lenght and decided where they are conncted or not?

4

I’m not sure, I think that would be the distance between a child joint and a parent joint.

5

So a joints center point is its base? Is there even a tip data in egg?
Not all bones have parents or children.

6

Bones in Panda (and most other engines) do not have a length, it is just a transform. Often for visualization it is useful to draw a line from the parent bone to each child bone. You could do this using Panda’s LineSegs.

7

You mean Panda or the egg format. Because isnt the lenght required for ik stuff?
I guess I could just have a predefined lenght for bones without any parent/child.

So anyway, i dont really know how to access the bone data.

8

Panda doesn’t do IK. As rdb says, a bone is just a transform, no more, no less.

David

9

so… how can i access the bones and their pos/loc/scale to apply to the visualising nodes?

10

actor.exposeJoint() is the easiest way. It’s documented in the manual.

David

11

this doesnt work:

from pandac.PandaModules import *
import direct.directbase.DirectStart
from direct.actor.Actor import Actor

actor = Actor("panda")
actor.reparentTo(render)

for i in actor.getJoints():
	joint = actor.exposeJoint(None, 'modelRoot', i.getName())
	b = loader.loadModel('bone')
	b.reparentTo(joint)
12

Some of those nodes from actor.getJoints() are CharacterSlider types and can’t be exposed.

from pandac.PandaModules import * 
import direct.directbase.DirectStart 
from direct.actor.Actor import Actor 

actor = Actor("panda") 
actor.reparentTo(render) 

for i in actor.getJoints():
   try:
      joint = actor.exposeJoint(None, 'modelRoot', i.getName())
   except AttributeError:
      print "Cannot expose", i.getName()
      continue
   b = loader.loadModel('bone') 
   b.reparentTo(joint)

run()
13

Not bad

but if there was a way to check if bone has parent and ‘connect’ those bones by scaling the child bone depending on their distance, then it would look better. I couldnt find a function for checking if joint has parent.
btw, what would be the best way to render bones in front of the mesh (x-ray)?

14

I quickly whipped this up for you:

from pandac.PandaModules import * 
loadPrcFileData("", "interpolate-frames #t")
import direct.directbase.DirectStart
from direct.actor.Actor import Actor
from random import random

actor = Actor("panda", {"walk" : "panda-walk.egg"})
actor.reparentTo(render)
actor.setBin('background', 1) 

def walkJointHierarchy(actor, part, parentNode = None, indent = ""):
    if isinstance(part, CharacterJoint):
        np = actor.exposeJoint(None, 'modelRoot', part.getName())

        if parentNode and parentNode.getName() != "root":
            lines = LineSegs()
            lines.setThickness(3.0)
            lines.setColor(random(), random(), random())
            lines.moveTo(0, 0, 0)
            lines.drawTo(np.getPos(parentNode))
            lnp = parentNode.attachNewNode(lines.create())
            lnp.setBin("fixed", 40)
            lnp.setDepthWrite(False)
            lnp.setDepthTest(False)

        parentNode = np

    for child in part.getChildren():
        walkJointHierarchy(actor, child, parentNode, indent + "  ")

walkJointHierarchy(actor, actor.getPartBundle('modelRoot'), None)

actor.loop("walk")
base.cam.setY(-50)

run()

The parentNode.getName() != “root” check is a hack, otherwise it draws lines from the root node, which is not desirable.

The setBin and setDepthTest/setDepthWrite calls make sure the bones are rendered last, and no depth testing is done, so that they show through everything.

15

Sweet. Ill try to use the bone shapes I made instead of linesegs, though.
If this was posted in the Code Snippets others would benefit from it too.

16

Feel free to. Public domain.