rope samples

Code Snippets
1

i just found this nice rope class, but couldn’t get it to work and/or modify its shape.
now i can, and if someone has the same problem, here are two small samples.
the first curve modification works with nodepaths, which is the simpler one (and maybe more useful).
the second sample shows you how to modify the vertices directly.

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

class Main(DirectObject):
    def __init__(self):
        base.setBackgroundColor(0.0, 0.0, 0.0, 1)
        base.cam.setPos(0, -100, 25)

        r = Rope()
        self.ropeVertex2NP = render.attachNewNode("ropeVertex2NP")
        self.ropeVertex3NP = render.attachNewNode("ropeVertex3NP")
        r.setup(4, [(None, (10, 0, 0)),
                    (None, (10, 0, 10)),
                    (self.ropeVertex2NP, (0, 0, 10)),
                    (self.ropeVertex3NP, (0, 10, 10)),
                    (None, (0, 10, 0)),
                    (None, (10, 10, 0))])
        r.reparentTo(render)
        
        taskMgr.add(self.modifyCurve, "modify")

    def modifyCurve(self, task):
        factor = globalClock.getDt() * 100.0 
        self.ropeVertex2NP.setZ(self.ropeVertex2NP.getZ()+(0.1*factor))
        self.ropeVertex3NP.setY(self.ropeVertex3NP.getY()+(0.1*factor))
        return task.cont
    
if __name__ == '__main__':
    m = Main()
    run()
from pandac.PandaModules import *
import direct.directbase.DirectStart
from direct.showbase.DirectObject import DirectObject
from direct.showutil.Rope import Rope

class Main(DirectObject):
    def __init__(self):
        base.setBackgroundColor(0.0, 0.0, 0.0, 1)
        base.cam.setPos(0, -100, 25)

        r = Rope()
        r.setup(4, [(None, (10, 0, 0)),
                    (None, (10, 0, 10)),
                    (None, (0, 0, 10)),
                    (None, (0, 10, 10)),
                    (None, (0, 10, 0)),
                    (None, (10, 10, 0))])
        r.reparentTo(render)
        
        self.curve = r.ropeNode.getCurve()
        
        taskMgr.add(self.modifyCurve, "modify")

    def modifyCurve(self, task):
        factor = globalClock.getDt() * 100.0 
        val2 = VBase4(self.curve.getVertex(2))
        val3 = VBase4(self.curve.getVertex(3))
        val2.setZ(val2.getZ()+(0.1*factor))
        val3.setY(val3.getY()+(0.1*factor))
        self.curve.setVertex(2, val2)
        self.curve.setVertex(3, val3)
        return task.cont
    
if __name__ == '__main__':
    m = Main()
    run()

greets

2

Thanks for the illustrative code!

Note that you can, incidentally, change the appearance of the Rope by directly fiddling with its ropeNode member (which is the C++ implementation of the rendering). There are several options. Try, for instance:

r.ropeNode.setRenderMode(RopeNode.RMTube)

The various render mode options support different effects for texturing, lighting, and vertex-coloring.

David

3

Hey, this is pretty neat, thanks for the example!

It would be really cool to combine this with ODE to create something like a rope-bridge.