Simulate a moving cable via python by blender game

Game Engine Game Engine Support and Discussion
1

Good afternoon people. I’m new to Blender and I’m having trouble drawing a Tube cable. I have the coordinates of a cable, and I made the cable design via bpy with

bpy.data.curves.new (" TubesCurve ", type = ‘CURVE’)
, passing the initial vertices, then transformed into a mesh, to use On the Game Engine.

Now I want to read a coordinate file via python and pass these coordinates to the vertices of the cable, thus simulating the cable in the Engine. The cable should change in real-time simulation, but I do not know how to do that. I tried with:

Create Cable:


from bge import logic as G
import bge
import os
import bpy


filename = 'posRef.csv'
directory = '/home/scholl/Dropbox/Mestrado/Dissertacao/Simulador/'  # <-- if you have linux or osx
#directory = r'C:\Users\MarcosScholl\Dropbox\Mestrado\Dissertacao\Simulador'  # <-- if windows, the r is important
# directory = 'c:/some/directory'  # <-- if windows (alternative)


fullpath = os.path.join(directory, filename)


OBJETO = bpy.data.objects.get("mesh")


if OBJETO:
    print ("TEM") 
else:
    print("NAO TEM")
    with open(fullpath, 'r', newline='') as csvfile:


        # split every row at the comma,, 
        rows = (r.split(',') for r in csvfile if r)
        
        # then take the first 3 values and cast them as float
        #verts = [[print(type(float(i))) for i in r[:3]] for r in rows]
        verts = [[0.0, 0.0, 0.0], [0.0012837268, 0.078448594, 0.99691731], [0.0012837268, 0.078448594, 1.9969172], [0.024165375, 0.31076986, 2.9692872], [0.074502848, 0.61565942, 3.9203436], [0.16748734, 0.98687434, 4.844223], [0.32043213, 1.4143264, 5.7352295], [0.55152732, 1.8829411, 6.5878696], [0.87808329, 2.3716667, 7.3968868], [1.3142259, 2.8528759, 8.1572924], [1.8680933, 3.2924564, 8.864399], [2.5387115, 3.6509092, 9.5138474], [3.3128924, 3.8857543, 10.101632], [4.1626806, 3.9554331, 10.624131], [5.0440435, 3.8246953, 11.078122], [5.8975968, 3.4711421, 11.460806], [6.6521206, 2.8921754, 11.769823],[7.2313609, 2.1111605, 12.003268], [7.5641031, 1.1812084, 12.159702], [7.5967212, 0.18482479, 12.238161], [7.3064365, -0.77211553, 12.238161], [6.7125735, -1.572847, 12.159702], [5.8824725, -2.108067, 12.003268], [4.9287863, -2.2977669, 11.769823], [3.9960041, -2.1122251, 11.460806], [3.2363274, -1.5864451, 11.078122], [2.7782586, -0.82220322, 10.624132], [2.6946852, 0.026331298, 10.101634], [2.9796615, 0.78349513, 9.5138493], [3.5430851, 1.2941526, 8.8644009], [4.2290006, 1.4659655, 8.1572943], [4.856319, 1.297876, 7.3968883]]


    if verts:


        out2 = []
        [out2.extend(list(i)+[0.0]) for i in verts] 


        # first coordinate is present by default, we add the (number of total verts) - 1
        num_points_to_add = len(verts) - 1
        curve = bpy.data.curves.new("TubesCurve", type='CURVE')
        curve.dimensions = '3D'
        curve.fill_mode = 'FULL'
        curve.bevel_depth = 0.015
        curve.bevel_resolution = 10
        
        
        polyline = curve.splines.new(type='POLY')
        polyline.points.add(num_points_to_add)
        
        # a flatterened list of [x1, y1, z1, x2, y2 .... y20, z20]
        print(out2)
        polyline.points.foreach_set('co', out2)


        obj = bpy.data.objects.new("mesh", curve)
        scene = bpy.context.scene
        scene.objects.link(obj)


obj = bpy.data.objects ['Tube']

for vertex in obj.data.vertices:

     vertex.co.x = xx [i]

     vertex.co.y = yy [i]

     vertex.co.z = zz [i]

But the cable does not move, but when I shut down the Engine, it is in the final position.

CaboModelagem.png1366×699 118 KB

Could anyone guide me how to do this?
Thank you for all the help you get.

2

you must use the game object referance to the game mesh
and you can’t use curves in the engine only meshes…

import bge

cont = bge.logic.getCurrentController()
own = cont.owner

scene = own.scene
objectToEdit = own.scene[‘objectsName’]
mesh = objectToEdit.meshes[0]

To simulate a cable I would use rigid bodies and rigid body joints and a armature object using copy rot in its bones and

always--------and---------run armature

basically your cable is a ragdoll

if the cable does not need physics,
I would look into making custom curves using bge.render.drawLine

3

Thanks for the advice BluePrintRandom.

I do not know how I could do this hard body. Could you help me with a simple code with for example Cable with two joints?
I would really appreciate it, because I’ve been trying to find a solution for two days, but I could not.

4

ok, first off

ragbones = objects using rigid body physics in the physics tab

rigid body joint constraint is in the constraints tab

after making a chain of rigid bodies

make a armature and in each bone use copy rot targeting one of the rigid body objects

it’s actually quite easy once you get the hang of it,
I think Timster has a tutorial I will did for a minute.

so the rigid body chain is your physics simulation,
and the armature mesh is the visual representation of the chain

edit: