fix build and visualization for Python 3.8

[cmigliorini]

I was able to run this with Python 3.8 on a Catalina macOs, and to get Visualization working.

Still, apparently other stuff is broken, but I don't really know what I'm doing robot-wise.

To get there, I had to freeze wxPython to 4.0.7 as access to 2.8.12 is really not practical, and 4.1 breaks more things. As a consequence there is a good chance it'll never run under Python2 again, I did not even try.

If you think this must still be compatible with Python2, I can give it a go, but I'd rather fix more Python3-related issues.

[cmigliorini]

IGM - Pieper method is broken

Traceback (most recent call last):
  File "/Users/migperso/dev/symoro/symoroui/layout.py", line 1036, in OnIgmPieper
    model_symo = pieper.igm_pieper(self.robo, lst_T, n)
  File "/Users/migperso/dev/symoro/pysymoro/pieper.py", line 288, in igm_pieper
    _pieper_solve(robo, symo)
  File "/Users/migperso/dev/symoro/pysymoro/pieper.py", line 60, in _pieper_solve
    XXXRRR(robo,symo,com_key,X_joints,pieper_joints)
  File "/Users/migperso/dev/symoro/pysymoro/pieper.py", line 341, in XXXRRR
    solve_position(robo, symo, com_key, X_joints, fc, fs, fr, f0, g)
  File "/Users/migperso/dev/symoro/pysymoro/invdata.py", line 975, in solve_position
    dj_eq_0(robo, symo, X_joints, tc, ts, tr, t0, G, offset)
  File "/Users/migperso/dev/symoro/pysymoro/invdata.py", line 124, in dj_eq_0
    a = 2*(tc[x]*t1[x] + tc[y]*t1[y] + tc[z]*t1[z])
TypeError: 'Symbol' object is not subscriptable

[cmigliorini]

Could not get the zoom function to work properly, when holding both mouse buttons I get

wx._core.wxAssertionError: C++ assertion "!wxMouseCapture::IsInCaptureStack(this)" failed at /Users/robind/projects/bb2/dist-osx-py38/build/ext/wxWidgets/src/common/wincmn.cpp(3271) in CaptureMouse(): Recapturing the mouse in the same window?

[cmigliorini]

Regarding residual issue you had on IGM - Paul frame 7 :

Traceback (most recent call last):
  File "/Users/migperso/dev/symoro/symoroui/layout.py", line 1023, in OnIgmPaul
    model_symo = invgeom.igm_paul(self.robo, lst_T, n)
  File "/Users/migperso/dev/symoro/pysymoro/invgeom.py", line 178, in igm_paul
    _paul_solve(robo, symo, T_ref, 0, n)
  File "/Users/migperso/dev/symoro/pysymoro/invgeom.py", line 38, in _paul_solve
    chain = robo.loop_chain(m, n)
  File "/Users/migperso/dev/symoro/pysymoro/robot.py", line 590, in loop_chain
    k = self.common_root(i, j)
  File "/Users/migperso/dev/symoro/pysymoro/robot.py", line 613, in common_root
    u = self.chain(i)
  File "/Users/migperso/dev/symoro/pysymoro/robot.py", line 586, in chain
    j = self.ant[j]
IndexError: list index out of range

I should point out that Robot constructor initializes ant with

        # Index of antecedent joint: list of int.
        self.ant = list(range(-1, self.NF - 1))

Which creates a (7)-long array [-1, 0, 1, 2, 3, 4, 5]. Hence later calling self.ant[j] with j==7 obviously can't work. I don't know your code base enough to know whether it's a simple 0-based vs 1-based indexing issue, or if it has a deeper cause.

[cmigliorini]

Which creates a (7)-long array [-1, 0, 1, 2, 3, 4, 5]. Hence later calling self.ant[j] with j==7 obviously can't work. I don't know your code base enough to know whether it's a simple 0-based vs 1-based indexing issue, or if it has a deeper cause.

It could also be that self.NF should really be 7, not 6 ?

[cmigliorini]

It could also be that self.NF should really be 7, not 6 ?

matter of fact, rx90 does define only 6 frames.

def rx90():
    """Generate Robot instance of RX90"""
    robo = Robot('RX90', 6, 6, 6, False)