rml_post.py

#***************************************************************************
#*   (c) Jon Nordby (jononor@gmail.com) 2015                               *
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#*   This file is part of the FreeCAD CAx development system.              *
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TOOLTIP='''
FreeCAD Path post-processor to output code for the Roland Modela MDX-## machines.

The machine speaks RML-1, specified in 'Roland RML-1 Programming Guidelines'
https://itp.nyu.edu/classes/cdp-spring2014/files/2014/09/RML1_Manual.pdf
http://altlab.org/d/content/m/pangelo/ideas/rml_command_guide_en_v100.pdf

The format has some overlap with HPGL:
https://en.wikipedia.org/wiki/HPGL
http://paulbourke.net/dataformats/hpgl/
'''

import FreeCAD
import Part
import PostUtils

# to distinguish python built-in open function from the one declared below
if open.__module__ == '__builtin__':
    pythonopen = open


# Entrypoint used by FreeCAD
def export(objectslist, filename, argstring):
    "Export objects as Roland Modela code."

    code = ""
    for obj in objectslist:
        code += convertobject(obj)

    gfile = pythonopen(filename,"wb")
    gfile.write(code)
    gfile.close()

def convertobject(obj):
    gcode = obj.Path.toGCode()
    gcode = parse(gcode)
    return gcode

def motoron():
    return [ "!MC1;" ]
def motoroff():
    return [ "!MC0;" ]
def home():
    return [ "H;" ]

def setjog():
   # "!PZ%d,%d;",iz_down,iz_up); // set z down, jog
   return ""

def addheader():
    return [ "PA;PA;" ] # absolute positioning 
def addfooter():
    return []

def mm2cord(mm):
    mm = float(mm)
    return int(40.0*mm)

def feed(x=None, y=None, z=None, state={}):
    c = []

    if x is not None:
        x = float(x)
        state['X'] = x
    if y is not None:
        y = float(y)
        state['Y'] = y
    if z is not None:
        z = float(z)
        state['Z'] = z

    if x is not None and y is not None and z is not None:
        # 3d motion
        c.append("Z%d,%d,%d;" % (mm2cord(x), mm2cord(y), mm2cord(z)))
    elif x is not None and y is not None:
        # 2d in XY plane
        c.append("PD%d,%d;" % (mm2cord(x), mm2cord(y)))
    elif z is not None:
        pass # XXX: is this used?
    return c

def jog(x=None, y=None, z=None, state={}):        
    c = []
    if x is not None and y is not None:
      x, y = float(x), float(y)
      c.append("PU%d,%d;" % (mm2cord(x), mm2cord(y)))
      state['X'] = x
      state['Y'] = y
    if z is not None:
      z = float(z)
      c.append("PU;")
      # TODO: use !ZZ command
      state['Z'] = z

    return c

def xyarc(args, state):
    # no native support in RML/Modela, convert to linear line segments
    c = []

    lastPoint = FreeCAD.Vector(state['X'], state['Y'])
    newPoint = FreeCAD.Vector(float(args['X']), float(args['Y']))
    centerOffset = FreeCAD.Vector(float(args['I']), float(args['J']))
    center = lastPoint + centerOffset
    radius = (center - lastPoint).Length
    xyNormal = FreeCAD.Vector(0, 0, 1)
    circle = Part.Circle(center, xyNormal, radius)
    p0 = circle.parameter(lastPoint)
    p1 = circle.parameter(newPoint)
    arc = Part.ArcOfCircle(circle, p0, p1)
    steps = 64 # TODO: specify max error instead
    points = arc.discretize(steps)
    # TODO: consider direction
    #print 'p = Part.ArcOfCircle(Part.Circle(FreeCAD.Vector(%f, %f), FreeCAD.Vector(0, 0, 1), %f), %f, %f)' % (center.x, center.y, radius, p0, p1)
    for p in points:
        #print 'p', p.x, p.y
        c += feed(p.x, p.y, state['Z'], state)
    return c

def speed(xy=None, z=None, state={}):
    c = []
    print xy, z, state
    if xy is not None:
        xy = float(xy)
        if xy > 0.0 and xy != state['XYspeed']:
            c.append("VS%.1f;" % xy)
            state['XYspeed'] = xy
    if z is not None:
        z = float(z)
        if z > 0.0 and z != state['Zspeed']:
            c.append("!VZ%.1f;" % z)
            state['Zspeed'] = z
    return c

def convertgcode(cmd, args, state):
    """Convert a single gcode command to equivalent Roland code"""
    if cmd == 'G0':
        # jog
        return jog(args['X'], args['Y'], args['Z'], state)
    elif cmd == 'G1':
        # linear feed
        c = []
        # feedrate
        c += speed(xy=args['F'], z=args['F'], state=state)
        # motion
        c += feed(args['X'], args['Y'], args['Z'], state)
        return c
    elif cmd == 'G2' or cmd == 'G3':
        # arc feed
        c = []
        # feedrate
        c += speed(xy=args['F'], state=state)
        # motion
        if args['X'] and args['Y'] and args['Z']:
            # helical motion
            pass
        elif args['X'] and args['Y']:
            # arc in plane
            c += xyarc(args, state)
        return c
    elif cmd == 'G20':
        # inches mode
        raise ValueError("rml_post: Inches mode not supported")
    elif cmd == 'G21':
        # millimeter mode
        return ""
    elif cmd == 'G40':
        # tool compensation off
        return ""
    elif cmd == 'G80':
        # cancel all cycles (drill normally)
        return "PU;"
    elif cmd == 'G81':
        c = []
        # feedrate
        c += speed(z=args['F'], state=state)
        # motion
        c += jog(args['X'], args['Y'], state=state)
        c += feed(args['X'], args['Y'], args['Z'], state)
        return c
    elif cmd == 'G90':
        # absolute mode?
        return ""
    elif cmd == 'G98':
        # feedrate
        return ""
    else:
        raise NotImplementedError("rml_post: GCode command %s not understood" % (cmd,))

    raise Exception("should not be reached. cmd=%s" % (cmd,))


def parse(inputstring):
    "parse(inputstring): returns a parsed output string"
    
    state = { 'X': 0.0, 'Y': 0.0, 'Z': 0.0, 'XYspeed': -1.0, 'Zspeed': -1.0 }
    output = []

    # header
    output += addheader()
    output += motoron()
    
    output += speed(2.0, 1.0, state) # defaults

    # TODO: respect clearance height
    
    # treat the input line by line
    lines = inputstring.split("\n")
    for line in lines:
        if not line:
            continue
        parsed = PostUtils.stringsplit(line)
        command = parsed['command']
        print 'cmd', line
        try:
            if command:
                code = convertgcode(command, parsed, state)
                if not isinstance(code, list):
                    code = [ code ]
                if len(code) and code[0]:
                    output += code
        except NotImplementedError, e:
            print e

    # footer
    output += motoroff()
    output += home()
    output += addfooter()

    return '\n'.join(output)

print __name__ + " gcode postprocessor loaded."