3D Ball Collision in Python with Visual Module.

I only compute the collision between bed and blue one. They're bola[1] and bola[2] respectively

from visual import *
from random import uniform,random
from visual.controls import *

def change(): 
    global jalan
    if b.value:
        jalan  = True
        for ball in(bola):
            ball.vx  = uniform(-7,7)
            ball.vy  = uniform(-7,7)
            ball.vz  = uniform(-7,7)
    else:
        jalan   = False
        
c = controls(title='Tempat Tombol',x=800, y=0, width=300, height=300, range=50) 
b = toggle( pos=(0,0), width=20, height=20, text='Click me', action=lambda: change() )
display(center=(0,0,0),background=(1,1,1), #autoscale=False,        
        width=600, height=600,  forward=(-0.4,-0.3,-1)) #arah kamera
g   = -1.
dt  = .1
e   = 1.
b.value = True
jalan   = True
l       = 17.
dl      = .01
n       = 11

distant_light(direction=(1,1,1), color=color.red)
lantai      = box(color=color.white, pos=(0,0,0),length=l,height=dl, width=l, opacity=.3)
dindingKiri = box(color=color.white, pos=(-l/2,l/2,0),length=dl,height=l, width=l, opacity=.3)
dindingKanan= box(color=color.white, pos=(l/2,l/2,0),length=dl,height=l, width=l, opacity=.3)
dBelakang   = box(color=color.white, pos=(0,l/2,-l/2),length=l,height=l, width=dl, opacity=.3)
atap        = box(color=color.white, pos=(0,l,0),length=l,height=dl, width=l, opacity=.3)
bola = [] 
for i in arange(n):
    ball = sphere (pos=(uniform(1,7),0,uniform(-7,7)), radius=.3, color=color.green)
    ball.v  = vector(uniform(-7,7),uniform(-7,7),uniform(-7,7))
    bola.append(ball)


bola[1].radius = 2.5
bola[2].radius = 2.5

bola[1].color = color.red
bola[2].color = color.blue
def proses():
    for ball in (bola):
        a       = g
        ball.v[1]      += a*dt
        ball.pos+= ball.v*dt
    tumbukan()
    tumbukanBola()
    
def tumbukan():
    for ball in(bola):
        if ball.y<0:
            ball.y  = 0.01
            ball.v[1]  *=-1.*e
        elif ball.y>l:
            ball.y  = l-.01
            ball.v[1]  *= -1
        if ball.x<-l/2:
            ball.x=-l/2+.01
            ball.v[0]  *= -1*e
        if ball.x>l/2:
            ball.x=l/2-.01
            ball.v[0]  *= -1*e
        if ball.z<-l/2:
            ball.z=-l/2+.01
            ball.v[2]  *= -1*e
        if ball.z>l/2:
            ball.z=l/2-.01
            ball.v[2]  *= -1*e

def tumbukanBola():
    #pass
    jarak = mag(bola[2].pos-bola[1].pos)
    if jarak<(bola[1].radius+bola[2].radius):
        arah    = norm(bola[2].pos-bola[1].pos)
        v1      = dot(bola[1].v,arah)
        v2      = dot(bola[2].v,arah)
        dv      = v2-v1
        bola[1].v   += dv*arah
        bola[2].v   -= dv*arah 



while 1:
    rate (51)
    if jalan:
        proses()
    
    
    
    

    

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