Strange Rope behavior

Scripting Issues
#1

Hi to all of you

I have been playing arround with the ropes and found a very strange behavior

the code of RopeTestA

from pandac.PandaModules import *
import direct.directbase.DirectStart
from direct.showbase.DirectObject import DirectObject
from direct.showutil.Rope import Rope


from numpy import arange, cos, linspace, pi, sin, random
from scipy.interpolate import splprep, splev, interp1d
import scipy

class Main(DirectObject):
    def __init__(self):

        self.a = []
        base.setBackgroundColor(0.0, 0.0, 0.0, 1)
        base.cam.setPos(0, -100, 25)

        self.Light()
        self.GenerateTextures()


        # make ascending spiral in 3-space
        t=linspace(0,1.75*2*pi,100)

        x = sin(t)
        y = cos(t)
        z = t

        # spline parameters
        s=3.0 # smoothness parameter
        k=3 # spline order
        nest=-1 # estimate of number of knots needed (-1 = maximal)

        self.tckp,self.u = splprep([x,y,z],s=s,k=k,nest=-1)
        # Kontrollpunkte in 3D laden  
        for i in range (len(self.tckp[1][0])):
            self.a.append( (None,(self.tckp[1][0][i],self.tckp[1][1][i],self.tckp[1][2][i])))
            self.KPoint = loader.loadModel("BallSmall")
            self.KPoint.setPos(self.tckp[1][0][i],self.tckp[1][1][i],self.tckp[1][2][i])
            self.KPoint.setTexture(self.texGrayPink)
            self.KPoint.reparentTo(render)

        # Seil in 3D laden
        self.r = Rope()
        self.r.setup(4, self.a,self.tckp[0])
        self.r.reparentTo(render)       
        #self.curve = self.r.ropeNode.getCurve()


    def Light(self):
        alight = AmbientLight('alight')
        alight.setColor(VBase4(0.2, 0.2, 0.2, 1))
        alnp = render.attachNewNode(alight)
        render.setLight(alnp)

        dlight = DirectionalLight('dlight')
        dlight.setColor(VBase4(0.8, 0.8, 0.5, 1))
        dlnp = render.attachNewNode(dlight)
        dlnp.setHpr(0, -60, 0)
        render.setLight(dlnp)

    def GenerateTextures(self):

        self.texGrayPink = loader.loadTexture("/../Corsair/3DSteuerung/PandaProgramm/models//GrayPink.jpg")
        self.texPink = loader.loadTexture("/../Corsair/3DSteuerung/PandaProgramm/models//Pink.jpg")
        self.texLime = loader.loadTexture("/../Corsair/3DSteuerung/PandaProgramm/models//Lime.jpg")


if __name__ == '__main__':
    m = Main()
    run()

and RopetestB

from pandac.PandaModules import *
import direct.directbase.DirectStart
from direct.showbase.DirectObject import DirectObject
from direct.showutil.Rope import Rope


from numpy import arange, cos, linspace, pi, sin, random
from scipy.interpolate import splprep, splev, interp1d
import scipy

class Main(DirectObject):
    def __init__(self):

        self.a = []
        base.setBackgroundColor(0.0, 0.0, 0.0, 1)
        base.cam.setPos(0, -100, 25)

        self.Light()
        self.GenerateTextures()


        # make ascending spiral in 3-space
        t=linspace(0,1.75*2*pi,100)

        x = sin(t)
        y = cos(t)
        z = t

        # spline parameters
        s=3.0 # smoothness parameter
        k=3 # spline order
        nest=-1 # estimate of number of knots needed (-1 = maximal)

        self.tckp,self.u = splprep([x,y,z],s=s,k=k,nest=-1)
        # Kontrollpunkte in 3D laden  


        # Seil in 3D laden
        self.r = Rope()
        self.r.setup(4, self.a,self.tckp[0])
        self.r.reparentTo(render)       
        #self.curve = self.r.ropeNode.getCurve()
        
        for i in range (len(self.tckp[1][0])):
            self.a.append( (None,(self.tckp[1][0][i],self.tckp[1][1][i],self.tckp[1][2][i])))
            self.KPoint = loader.loadModel("BallSmall")
            self.KPoint.setPos(self.tckp[1][0][i],self.tckp[1][1][i],self.tckp[1][2][i])
            self.KPoint.setTexture(self.texGrayPink)
            self.KPoint.reparentTo(render)


    def Light(self):
        alight = AmbientLight('alight')
        alight.setColor(VBase4(0.2, 0.2, 0.2, 1))
        alnp = render.attachNewNode(alight)
        render.setLight(alnp)

        dlight = DirectionalLight('dlight')
        dlight.setColor(VBase4(0.8, 0.8, 0.5, 1))
        dlnp = render.attachNewNode(dlight)
        dlnp.setHpr(0, -60, 0)
        render.setLight(dlnp)

    def GenerateTextures(self):

        self.texGrayPink = loader.loadTexture("/../Corsair/3DSteuerung/PandaProgramm/models//GrayPink.jpg")
        self.texPink = loader.loadTexture("/../Corsair/3DSteuerung/PandaProgramm/models//Pink.jpg")
        self.texLime = loader.loadTexture("/../Corsair/3DSteuerung/PandaProgramm/models//Lime.jpg")


if __name__ == '__main__':
    m = Main()
    run()

only differ in the position of the insertation of the KontrollPointsbut RopetestB throws an
assertation error
in Line 40->
self.recompute line 69 ->self.curve.setKnot(i,self.knots.size[i]) line 124
-> AssertationError: i>=00 && < (int)_knots.size() line 106 in nurbsCurveEvaluator.cxx

Could anyone advise?

with kind regards

Martin
[/img]

#2

In case B, at the time you call setup(), you are passing an empty list, self.a. You don’t populate the list until after you call setup(), which is obviously too late.

David

#3

Thx David I missed the obvious