224 lines
11 KiB
Python
224 lines
11 KiB
Python
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#!/usr/bin/env python
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"""\
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G-code preprocessor for grbl
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- Converts G02/03 arcs to G01 linear interpolations
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- Removes comments, block delete characters, and line numbers
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- Removes spaces and capitalizes commands
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- Minor input error checking
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- OPTIONAL: Remove unsupported grbl G and M commands
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TODO:
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- More robust error checking
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- Improve interface to command line options
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- Improve g-code parsing to NIST standards
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- Fix problem with inverse feed rates
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- Positioning updates may not be correct on grbl. Need to check.
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Based on GRBL 0.7b source code by Simen Svale Skogsrud
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Version: 20100825
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"""
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import re
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from math import *
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from copy import *
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# -= SETTINGS =-
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filein = 'test.gcode' # Input file name
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fileout = 'grbl.gcode' # Output file name
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ndigits_in = 4 # inch significant digits after '.'
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ndigits_mm = 2 # mm significant digits after '.'
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mm_per_arc_segment = 0.1 # mm per arc segment
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inch2mm = 25.4 # inch to mm conversion scalar
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verbose = False # Verbose flag to show all progress
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remove_unsupported = True # Removal flag for all unsupported statements
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# Initialize parser state
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gc = { 'current_xyz' : [0,0,0],
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'feed_rate' : 0, # F0
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'motion_mode' : 'SEEK', # G00
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'plane_axis' : [0,1,2], # G17
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'inches_mode' : False, # G21
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'inverse_feedrate_mode' : False, # G94
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'absolute_mode' : True} # G90
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def unit_conv(val) : # Converts value to mm
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if gc['inches_mode'] : val *= inch2mm
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return(val)
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def fout_conv(val) : # Returns converted value as rounded string for output file.
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if gc['inches_mode'] : return( str(round(val/inch2mm,ndigits_in)) )
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else : return( str(round(val,ndigits_mm)) )
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# Open g-code file
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fin = open(filein,'r');
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fout = open(fileout,'w');
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# Iterate through g-code file
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l_count = 0
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for line in fin:
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l_count += 1 # Iterate line counter
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# Strip comments/spaces/tabs/new line and capitalize. Comment MSG not supported.
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block = re.sub('\s|\(.*?\)','',line).upper()
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block = re.sub('\\\\','',block) # Strip \ block delete character
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block = re.sub('%','',block) # Strip % program start/stop character
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if len(block) == 0 : # Ignore empty blocks
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print "Skipping: " + line.strip()
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else : # Process valid g-code clean block. Assumes no block delete characters or comments
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g_cmd = re.findall(r'[^0-9\.\-]+',block) # Extract block command characters
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g_num = re.findall(r'[0-9\.\-]+',block) # Extract block numbers
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# G-code block error checks
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# if len(g_cmd) != len(g_num) : print block; raise Exception('Invalid block. Unbalanced word and values.')
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if 'N' in g_cmd :
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if g_cmd[0]!='N': raise Exception('Line number must be first command in line.')
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if g_cmd.count('N') > 1: raise Exception('More than one line number in block.')
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g_cmd = g_cmd[1:] # Remove line number word
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g_num = g_num[1:]
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# Block item repeat checks? (0<=n'M'<5, G/M modal groups)
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# Initialize block state
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blk = { 'next_action' : 'DEFAULT',
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'absolute_override' : False,
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'target_xyz' : deepcopy(gc['current_xyz']),
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'offset_ijk' : [0,0,0],
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'radius_mode' : False,
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'unsupported': [] }
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# Pass 1
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for cmd,num in zip(g_cmd,g_num) :
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fnum = float(num)
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inum = int(fnum)
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if cmd is 'G' :
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if inum is 0 : gc['motion_mode'] = 'SEEK'
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elif inum is 1 : gc['motion_mode'] = 'LINEAR'
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elif inum is 2 : gc['motion_mode'] = 'CW_ARC'
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elif inum is 3 : gc['motion_mode'] = 'CCW_ARC'
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elif inum is 4 : blk['next_action'] = 'DWELL'
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elif inum is 17 : gc['plane_axis'] = [0,1,2] # Select XY Plane
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elif inum is 18 : gc['plane_axis'] = [0,2,1] # Select XZ Plane
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elif inum is 19 : gc['plane_axis'] = [1,2,0] # Select YZ Plane
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elif inum is 20 : gc['inches_mode'] = True
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elif inum is 21 : gc['inches_mode'] = False
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elif inum in [28,30] : blk['next_action'] = 'GO_HOME'
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elif inum is 53 : blk['absolute_override'] = True
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elif inum is 80 : gc['motion_mode'] = 'MOTION_CANCEL'
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elif inum is 90 : gc['absolute_mode'] = True
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elif inum is 91 : gc['absolute_mode'] = False
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elif inum is 92 : blk['next_action'] = 'SET_OFFSET'
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elif inum is 93 : gc['inverse_feedrate_mode'] = True
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elif inum is 94 : gc['inverse_feedrate_mode'] = False
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else :
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print 'Unsupported command ' + cmd + num + ' on line ' + str(l_count)
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if remove_unsupported : blk['unsupported'].append(zip(g_cmd,g_num).index((cmd,num)))
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elif cmd is 'M' :
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if inum in [0,1] : pass # Program Pause
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elif inum in [2,30,60] : pass # Program Completed
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elif inum is 3 : pass # Spindle Direction 1
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elif inum is 4 : pass # Spindle Direction -1
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elif inum is 5 : pass # Spindle Direction 0
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else :
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print 'Unsupported command ' + cmd + num + ' on line ' + str(l_count)
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if remove_unsupported : blk['unsupported'].append(zip(g_cmd,g_num).index((cmd,num)))
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elif cmd is 'T' : pass # Tool Number
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# Pass 2
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for cmd,num in zip(g_cmd,g_num) :
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fnum = float(num)
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if cmd is 'F' : gc['feed_rate'] = unit_conv(fnum) # Feed Rate
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elif cmd in ['I','J','K'] : blk['offset_ijk'][ord(cmd)-ord('I')] = unit_conv(fnum) # Arc Center Offset
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elif cmd is 'P' : p = fnum # Misc value parameter
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elif cmd is 'R' : r = unit_conv(fnum); blk['radius_mode'] = True # Arc Radius Mode
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elif cmd is 'S' : pass # Spindle Speed
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elif cmd in ['X','Y','Z'] : # Target Coordinates
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if (gc['absolute_mode'] | blk['absolute_override']) :
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blk['target_xyz'][ord(cmd)-ord('X')] = unit_conv(fnum)
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else :
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blk['target_xyz'][ord(cmd)-ord('X')] += unit_conv(fnum)
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# Execute actions
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if blk['next_action'] is 'GO_HOME' :
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gc['current_xyz'] = deepcopy(blk['target_xyz']) # Update position
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elif blk['next_action'] is 'SET_OFFSET' :
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pass
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elif blk['next_action'] is 'DWELL' :
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if p < 0 : raise Exception('Dwell time negative.')
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else : # 'DEFAULT'
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if gc['motion_mode'] is 'SEEK' :
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gc['current_xyz'] = deepcopy(blk['target_xyz']) # Update position
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elif gc['motion_mode'] is 'LINEAR' :
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gc['current_xyz'] = deepcopy(blk['target_xyz']) # Update position
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elif gc['motion_mode'] in ['CW_ARC','CCW_ARC'] :
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axis = gc['plane_axis']
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# Convert radius mode to ijk mode
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if blk['radius_mode'] :
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x = blk['target_xyz'][axis[0]]-gc['current_xyz'][axis[0]]
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y = blk['target_xyz'][axis[1]]-gc['current_xyz'][axis[1]]
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if not (x==0 and y==0) : raise Exception('Same target and current XYZ not allowed in arc radius mode.')
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h_x2_div_d = -sqrt(4 * r*r - x*x - y*y)/hypot(x,y)
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if isnan(h_x2_div_d) : raise Exception('Floating point error in arc conversion')
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if gc['motion_mode'] is 'CCW_ARC' : h_x2_div_d = -h_x2_div_d
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if r < 0 : h_x2_div_d = -h_x2_div_d
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blk['offset_ijk'][axis[0]] = (x-(y*h_x2_div_d))/2;
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blk['offset_ijk'][axis[1]] = (y+(x*h_x2_div_d))/2;
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# Compute arc center, radius, theta, and depth parameters
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theta_start = atan2(-blk['offset_ijk'][axis[0]], -blk['offset_ijk'][axis[1]])
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theta_end = atan2(blk['target_xyz'][axis[0]] - blk['offset_ijk'][axis[0]] - gc['current_xyz'][axis[0]], \
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blk['target_xyz'][axis[1]] - blk['offset_ijk'][axis[1]] - gc['current_xyz'][axis[1]])
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if theta_end < theta_start : theta_end += 2*pi
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radius = hypot(blk['offset_ijk'][axis[0]], blk['offset_ijk'][axis[1]])
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depth = blk['target_xyz'][axis[2]]-gc['current_xyz'][axis[2]]
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center_x = gc['current_xyz'][axis[0]]-sin(theta_start)*radius
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center_y = gc['current_xyz'][axis[1]]-cos(theta_start)*radius
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# Compute arc incremental linear segment parameters
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angular_travel = theta_end-theta_start
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if gc['motion_mode'] is 'CCW_ARC' : angular_travel = angular_travel-2*pi
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millimeters_of_travel = hypot(angular_travel*radius, fabs(depth))
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if millimeters_of_travel is 0 : raise Exception('G02/03 arc travel is zero')
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segments = int(round(millimeters_of_travel/mm_per_arc_segment))
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if segments is 0 : raise Exception('G02/03 zero length arc segment')
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# ??? # if gc['inverse_feedrate_mode'] : gc['feed_rate'] *= segments
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theta_per_segment = angular_travel/segments
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depth_per_segment = depth/segments
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# Generate arc linear segments
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if verbose: print 'Converting: '+ block + ' : ' + str(l_count)
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fout.write('G01F'+fout_conv(gc['feed_rate']))
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if not gc['absolute_mode'] : fout.write('G90')
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arc_target = [0,0,0]
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for i in range(1,segments+1) :
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if i < segments :
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arc_target[axis[0]] = center_x + radius * sin(theta_start + i*theta_per_segment)
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arc_target[axis[1]] = center_y + radius * cos(theta_start + i*theta_per_segment)
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arc_target[axis[2]] = gc['current_xyz'][axis[2]] + i*depth_per_segment
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else :
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arc_target = deepcopy(blk['target_xyz']) # Last segment at target_xyz
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# Write only changed variables.
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if arc_target[0] != gc['current_xyz'][0] : fout.write('X'+fout_conv(arc_target[0]))
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if arc_target[1] != gc['current_xyz'][1] : fout.write('Y'+fout_conv(arc_target[1]))
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if arc_target[2] != gc['current_xyz'][2] : fout.write('Z'+fout_conv(arc_target[2]))
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fout.write('\n')
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gc['current_xyz'] = deepcopy(arc_target) # Update position
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if not gc['absolute_mode'] : fout.write('G91\n')
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# Rebuild original gcode block sans line numbers, extra characters, and unsupported commands
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if gc['motion_mode'] not in ['CW_ARC','CCW_ARC'] :
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if remove_unsupported and len(blk['unsupported']) :
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for i in blk['unsupported'][::-1] : del g_cmd[i]; del g_num[i]
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out_block = "".join([i+j for (i,j) in zip(g_cmd,g_num)])
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if len(out_block) :
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if verbose : print "Writing: " + out_block + ' : ' + str(l_count)
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fout.write(out_block + '\n')
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print 'Done!'
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# Close files
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fin.close()
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fout.close()
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