random lines between rendered objects python

Question

I am making a very basic 3d engine. When I render 2 or more objects, it draws lines between them. I do not know why this happens, as I coded the pen to go up after drawing every triangle. A strange thing is that when I draw a background line, each object also draws lines to the background line. I am confused. There is only 1 reason I could think of; it uses the last point of the other object as the first point of the first triangle of the main object. However, it does not seem like this is the case, as it is even happening with a simple line in the background as well.

from turtle import*
from time import*
from math import*
wn=Screen()
speed(0)
ht()
pu()
wn.tracer(0,0)
fov=200
camx=0
camy=0
camz=-5
xoff=0
yoff=0
zoff=0
xrot=pi*2
yrot=pi
zrot=pi
def goto3d(x,y,z):
  rotxx=x
  rotxy=y*cos(yrot)-z*sin(yrot)
  rotxz=y*sin(yrot)+z*cos(yrot)
  rotyx=rotxx*cos(xrot)+rotxz*sin(xrot)
  rotyy=rotxy
  rotyz=rotxz*cos(xrot)-rotxx*sin(xrot)
  rotzx=rotyx*cos(zrot)-rotyy*sin(zrot)
  rotzy=rotyx*sin(zrot)+rotyy*cos(zrot)
  rotzz=rotyz
  transx=rotzx-xoff
  transy=rotzy-yoff
  transz=rotzz-zoff
  newx=fov*transx/transz
  newy=fov*transy/transz
  if transz<0.1 or newx<=-200 or newy<=-200 or newx>=200 or newy>=200:
    return
  goto(newx,newy)
def triangle(p1x,p1y,p1z,p2x,p2y,p2z,p3x,p3y,p3z):
  goto3d(p1x,p1y,p1z)
  pd()
  goto3d(p2x,p2y,p2z)
  goto3d(p3x,p3y,p3z)
  goto3d(p1x,p1y,p1z)
  pu()
def face(p1x,p1y,p1z,p2x,p2y,p2z,p3x,p3y,p3z,p4x,p4y,p4z,r,g,b,a):
  fillcolor(r,g,b,a)
  begin_fill()
  triangle(p1x,p1y,p1z,p2x,p2y,p2z,p3x,p3y,p3z)
  end_fill()
  begin_fill()
  triangle(p2x,p2y,p2z,p3x,p3y,p3z,p4x,p4y,p4z)
  end_fill()
def bbox(x,y,z,w,h,l,r,g,b,a):
  x+=camx
  y+=camy
  z+=camz
  face(x+-w,y+h,z+l,x+w,y+h,z+l,x+-w,y+-h,z+l,x+w,y+-h,z+l,r,g,b,a)
  face(x+-w,y+h,z+-l,x+w,y+h,z+-l,x+-w,y+-h,z+-l,x+w,y+-h,z+-l,r,g,b,a)
  face(x+-w,y+h,z+l,x+-w,y+h,z+-l,x+-w,y+-h,z+l,x+-w,y+-h,z+-l,r,g,b,a)
  face(x+w,y+h,z+l,x+w,y+h,z+-l,x+w,y+-h,z+l,x+w,y+-h,z+-l,r,g,b,a)
  face(x+-w,y+-h,z+l,x+-w,y+-h,z+-l,x+w,y+-h,z+l,x+w,y+-h,z+-l,r,g,b,a)
  face(x+-w,y+h,z+l,x+-w,y+h,z+-l,x+w,y+h,z+l,x+w,y+h,z+-l,r,g,b,a)
def box(x,y,z,w,h,l,r,g,b):
  if w>=2 or h>=2 or l>=2:
    bbox(x-(w/4),y-(h/4),z-(l/4),w/4,h/4,l/4,r,g,b,.2)
    bbox(x+(w/4),y-(h/4),z-(l/4),w/4,h/4,l/4,r,g,b,.2)
    bbox(x+(w/4),y+(h/4),z-(l/4),w/4,h/4,l/4,r,g,b,.2)
    bbox(x-(w/4),y+(h/4),z-(l/4),w/4,h/4,l/4,r,g,b,.2)
    bbox(x-(w/4),y-(h/4),z+(l/4),w/4,h/4,l/4,r,g,b,.2)
    bbox(x+(w/4),y-(h/4),z+(l/4),w/4,h/4,l/4,r,g,b,.2)
    bbox(x+(w/4),y+(h/4),z+(l/4),w/4,h/4,l/4,r,g,b,.2)
    bbox(x-(w/4),y+(h/4),z+(l/4),w/4,h/4,l/4,r,g,b,.2)
  else:
    bbox(x,y,z,w,h,l,r,g,b,.5)
def render():
  goto(-200,-5)
  pd()
  goto(200,-5)
  pu()
  ### ||| objects go here ||| ###
  ### ||| format is box(x,y,z,width,height,length,r,g,b) ||| ###
  box(2,0,-5,2,2,2,0,255,255)
  box(0,0,0,1,1,1,255,0,0)
def tl():
  global xrot
  xrot-=pi/40
def tr():
  global xrot
  xrot+=pi/40
def f():
  global camx
  global camz
  camz+=.3*cos(-xrot)
  camx+=-(.3*sin(-xrot))
def b():
  global camx
  global camz
  camz+=-(.3*cos(-xrot))
  camx+=.3*sin(-xrot)
wn.onkey(tl,'Left')
wn.onkey(tr,'Right')
wn.onkey(f,'Up')
wn.onkey(b,'Down')
wn.listen()
while True:
  clear()
  render()
  update()