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mxs2py: a maxscript to python transpiler

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mxs2py takes a MAXScript program, parses it to a syntax tree, and then produces equivalent Python code from the syntax tree.

Why?

Help python programmers make sense of maxscript samples by providing automatic translation to python.

State of the Project

This is experimental work

As things are:

  • most correct maxcript syntax will be parsed correctly
  • parsing errors are poorly reported (trying to translate invalid maxscript code will not be a fun experience)
  • some maxscript constructs are still not supported by the code generator. Most of the time, when things cannot be translated to python, a warning is emitted in the generated code explaining why.
  • constructs like plugin, tool, custom attributes, etc. are parsed but then the python support is either inexistant or limited
  • some generated python constructions may be correct but awkward (because implementing it this way was easier)

Example

The following maxscript code from the maxcript howtos

renderers.current = Default_Scanline_Renderer()
delete $VoxelBox*
rbmp = render outputsize:[32,32] channels:#(#zdepth) vfb:off
z_d = getchannelasmask rbmp #zdepth
progressstart "Rendering Voxels..."
for y = 1 to rbmp.height do
(
 if not progressupdate (100.0 * y / rbmp.height) then exit
 pixel_line = getpixels rbmp [0,y-1] rbmp.width
 z_line = getpixels z_d [0,y-1] rbmp.width
 for x = 1 to rbmp.width do
 (
  b = box width:10 length:10 height:(z_line[x].value/2)
  b.pos = [x*10,-y*10,0]
  b.wirecolor = pixel_line[x]
  b.name = uniquename "VoxelBox"
 )--end x loop
)--end y loop
progressend()

Will be translated into the following python code: (which is essentially the same as zdepthchannel, but mechanically translated).

'''Converted from MAXScript to Python with mxs2py'''
from pymxs import runtime as rt
import mxsshim
rt.renderers.current = rt.default_scanline_renderer()
rt.delete(mxsshim.path("$VoxelBox*"))
rbmp = rt.render(outputsize=rt.point2(32, 32), channels=rt.array(rt.name("zdepth")), vfb=False)
z_d = rt.getchannelasmask(rbmp, rt.name("zdepth"))
rt.progressstart("Rendering Voxels...")
for y in range(int(1), 1 + int(rbmp.height)):
    if not rt.progressupdate(100.0 * y / rbmp.height):
        break
    pixel_line = rt.getpixels(rbmp, rt.point2(0, y - 1), rbmp.width)
    z_line = rt.getpixels(z_d, rt.point2(0, y - 1), rbmp.width)
    for x in range(int(1), 1 + int(rbmp.width)):
        b = rt.box(width=10, length=10, height=(z_line[x - 1].value / 2))
        b.pos = rt.point3(x * 10, -y * 10, 0)
        b.wirecolor = pixel_line[x - 1]
        b.name = rt.uniquename("VoxelBox")
# end x loop
# end y loop
rt.progressend()

Which works producing :

ouput

Under the hood

  • The code uses parsec to parse maxscript syntax into a syntax tree
  • It then appliees various transformations on the syntax tree (not in a very efficient way, but in a relatively simple way)
  • It then emits python code from this syntax tree

How to use it

from mxs2py import topy

(output, _) = topy("rotate $ (angleaxis 90 [1,0,0])")
print(output)

this will print:

'''Converted from MAXScript to Python with mxs2py'''
from pymxs import runtime as rt
import mxsshim
import pymxs
rt.rotate(mxsshim.path("$"), rt.angleaxis(90, rt.point3(1, 0, 0)))

Note that the generated code depends on mxsshim.py which is a very early and incomplete emulation layer of maxscript constructs in python.