Add options to draw t-slots

[JarrettR]

As suggested by @ninetynein

[vmario89]

made some progress with this, but hanging to geht further because i am not used to work with vectors in complex number form (cmath)

the slots i got:

the tabs i have no clue yet

[vmario89]

#!/usr/bin/env python
'''
Copyright (C) 2017 Jarrett Rainier jrainier@gmail.com

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

'''
import inkex, cmath, math
from inkex import Circle
from inkex.paths import Path, ZoneClose, Move, Line, line, Curve
from lxml import etree
    
debugEn = False
def debugMsg(input):
    if debugEn:
        inkex.utils.debug(input)
    
def linesNumber(path):
    retval = -1
    for elem in path:
        debugMsg('linesNumber')
        debugMsg(elem)
        retval = retval + 1
    debugMsg('Number of lines : ' + str(retval))
    return retval

class QuickJointPath (Path):
    def Move(self, point):
        '''Append an absolute move instruction to the path, to the specified complex point'''
        debugMsg("- move: " + str(point))
        self.append(Move(point.real, point.imag))
        
    def Line(self, point):
        '''Add an absolute line instruction to the path, to the specified complex point'''
        debugMsg("- line: " + str(point))
        self.append(Line(point.real, point.imag))
            
    def close(self):
        '''Add a Close Path instriction to the path'''
        self.append(ZoneClose())

    def line(self, vector):
        '''Append a relative line command to the path, using the specified vector'''
        self.append(line(vector.real, vector.imag))

    def get_line(self, n):
        '''Return the end points of the nth line in the path as complex numbers, as well as whether that line closes the path.'''

        if isinstance(self[n], (Move, Line, ZoneClose)):
            start = complex(self[n].x, self[n].y)
        elif isinstance(self[n], Curve):
            start = complex(self[n].x4, self[n].y4)
        # If the next point in the path closes the path, go back to the start.
        end = None
        closePath = False
        if isinstance(self[n+1], ZoneClose):
            end = complex(self[0].x, self[0].y)
            closePath = True
        else:
            if isinstance(self[n+1], (Move, Line, ZoneClose)):
                end = complex(self[n+1].x, self[n+1].y)
            elif isinstance(self[n+1], Curve):
                end = complex(self[n+1].x4, self[n+1].y4)
        return (start, end, closePath)

class QuickJoint(inkex.EffectExtension):
    def add_arguments(self, pars):
        pars.add_argument('-s', '--side', type=int, default=0, help='Object face to tabify')
        pars.add_argument('-n', '--numtabs', type=int, default=1, help='Number of tabs to add')
        pars.add_argument('-l', '--numslots', type=int, default=1, help='Number of slots to add')
        pars.add_argument('-t', '--thickness', type=float, default=3.0, help='Material thickness')
        pars.add_argument('-k', '--kerf', type=float, default=0.14, help='Measured kerf of cutter')
        pars.add_argument('-u', '--units', default='mm', help='Measurement units')
        pars.add_argument('-f', '--flipside', type=inkex.Boolean, default=False, help='Flip side of lines that tabs are drawn onto')
        pars.add_argument('-a', '--activetab', default='', help='Tab or slot menus')
        pars.add_argument('-S', '--featureStart', type=inkex.Boolean, default=False, help='Tab/slot instead of space on the start edge')
        pars.add_argument('-E', '--featureEnd', type=inkex.Boolean, default=False, help='Tab/slot instead of space on the end edge')
        pars.add_argument('-T', '--tSlotEnable', type=inkex.Boolean, default=False, help='Enable to use t-slot definitions')
        pars.add_argument('-D', '--tSlotHoleDiameter', type=float, default=3.00, help='Diameter of t slot hole')
        pars.add_argument('-H', '--tSlotNutHeight', type=float, default=1.80, help='Height of t slot nut')
        pars.add_argument('-W', '--tSlotNutWidth', type=float, default=5.50, help='Width of t slot nut')
        pars.add_argument('-N', '--tSlotScrewWidth', type=float, default=3.10, help='Scew width of t slot')
        pars.add_argument('-d', '--tSlotScrewDepth', type=float, default=10.00, help='Screw depth of t slot')
                        
    def draw_parallel(self, start, guideLine, stepDistance):
        polR, polPhi = cmath.polar(guideLine)
        polR = stepDistance
        return (cmath.rect(polR, polPhi) + start)
        
    def draw_perpendicular(self, start, guideLine, stepDistance, invert = False):
        polR, polPhi = cmath.polar(guideLine)
        polR = stepDistance
        debugMsg(polPhi)
        if invert:  
            polPhi += (cmath.pi / 2)
        else:
            polPhi -= (cmath.pi / 2)
        debugMsg(polPhi)
        debugMsg(cmath.rect(polR, polPhi))
        return (cmath.rect(polR, polPhi) + start)

        
    def draw_box(self, start, lengthVector, height, kerf):

        # Kerf is a provided as a positive kerf width. Although tabs
        # need to be made larger by the width of the kerf, slots need
        # to be made narrower instead, since the cut widens them.

        # Calculate kerfed height and length vectors
        heightEdge = self.draw_perpendicular(0, lengthVector, height - kerf, self.flipside)
        lengthEdge = self.draw_parallel(lengthVector, lengthVector, -kerf)
        
        debugMsg("draw_box; lengthEdge: " + str(lengthEdge) + ", heightEdge: " + str(heightEdge))
        
        cursor = self.draw_parallel(start, lengthEdge, kerf/2)
        cursor = self.draw_parallel(cursor, heightEdge, kerf/2)
        
        path = QuickJointPath()
        path.Move(cursor)
        
        cursor += lengthEdge
        path.Line(cursor)
        
        cursor += heightEdge
        path.Line(cursor)
        
        cursor -= lengthEdge
        path.Line(cursor)

        cursor -= heightEdge
        path.Line(cursor)
        
        path.close()
        
        return path


    def draw_tabs(self, path, line):
        cursor, segCount, segment, closePath = self.get_segments(path, line, self.numtabs)
        
        # Calculate kerf-compensated vectors for the parallel portion of tab and space
        tabLine = self.draw_parallel(segment, segment, self.kerf)
        spaceLine = self.draw_parallel(segment, segment, -self.kerf)
        endspaceLine = segment

        # Calculate vectors for tabOut and tabIn: perpendicular away and towards baseline
        tabOut = self.draw_perpendicular(0, segment, self.thickness, not self.flipside)
        tabIn = self.draw_perpendicular(0, segment, self.thickness, self.flipside)

        debugMsg("draw_tabs; tabLine=" + str(tabLine) + " spaceLine=" + str(spaceLine) + " segment=" + str(segment))

        drawTab = self.featureStart
        newLines = QuickJointPath()

        # First line is a move or line to our start point  
        if isinstance(path[line], Move):
            newLines.Move(cursor)
        else:
            newLines.Line(cursor)
            
        for i in range(segCount):
            debugMsg("i = " + str(i))
            if drawTab == True:
                debugMsg("- tab")
                if self.options.tSlotEnable is False:
                    newLines.line(tabOut)
                    newLines.line(tabLine)
                    newLines.line(tabIn)
                else: #TODO
                    #self.options.tSlotNutHeight
                    #self.options.tSlotNutWidth
                    #self.options.tSlotScrewWidth
                    #self.options.tSlotScrewDepth
                    newLines.line(tabOut)
                    newLines.line(tabLine)
                    newLines.line(tabIn)
            else:
                if i == 0 or i == segCount - 1:
                    debugMsg("- endspace")
                    newLines.line(endspaceLine)
                else:
                    debugMsg("- space")
                    newLines.line(spaceLine)
            drawTab = not drawTab

        if closePath:
            newLines.close
        return newLines
        
    def add_new_path_from_lines(self, lines, line_style):
        slot_id = self.svg.get_unique_id('slot')
        g = etree.SubElement(self.svg.get_current_layer(), 'g', {'id':slot_id})

        line_atts = { 'style':line_style, 'id':slot_id+'-inner-close-tab', 'd':str(Path(lines)) }
        return etree.SubElement(g, inkex.addNS('path','svg'), line_atts )

    def get_segments(self, path, line, num):

        # Calculate number of segments, including all features and spaces
        segCount = num * 2 - 1
        if not self.featureStart: segCount = segCount + 1
        if not self.featureEnd: segCount = segCount + 1

        start, end, closePath = QuickJointPath(path).get_line(line)
        
        # Calculate the length of each feature prior to kerf compensation.
        # Here we divide the specified edge into equal portions, one for each feature or space.

        # Because the specified edge has no kerf compensation, the
        # actual length we end up with will be smaller by a kerf. We
        # need to use that distance to calculate our segment vector.
        edge = end - start
        edge = self.draw_parallel(edge, edge, -self.kerf)
        segVector = edge / segCount
        
        debugMsg("get_segments; start=" + str(start) + " end=" + str(end) + " edge=" + str(edge) + " segCount=" + str(segCount) + " segVector=" + str(segVector))
        
        return (start, segCount, segVector, closePath)

    def draw_slots(self, path):
        # Female slot creation

        cursor, segCount, segVector, closePath = self.get_segments(path, 0, self.numslots)

        # I'm having a really hard time wording why this is necessary, but it is.
        # get_segments returns a vector based on a narrower edge; adjust that edge to fit within the edge we were given.
        cursor = self.draw_parallel(cursor, segVector, self.kerf/2)

        newLines = []
        line_style = str(inkex.Style({ 'stroke': '#000000', 'fill': 'none', 'stroke-width': str(self.svg.unittouu('0.1mm')) }))
        drawSlot = self.featureStart

        for i in range(segCount):
            if drawSlot:
                slot = self.add_new_path_from_lines(self.draw_box(cursor, segVector, self.thickness, self.kerf), line_style)
                if self.options.tSlotEnable is True:
                    cx, cy = slot.bounding_box().center       
                    circle = slot.getparent().add(inkex.Circle(id=self.svg.get_unique_id('tSlotHole')))
                    circle.set('transform', "rotate({:0.6f} {:0.6f} {:0.6f})".format(0, cx, cy))
                    circle.set('r', "{:0.6f}".format(self.tSlotHoleDiameter / 2 - self.kerf))
                    circle.set('cx', "{:0.6f}".format(cx))
                    circle.set('cy', "{:0.6f}".format(cy))
                    circle.style = line_style
                
            cursor = cursor + segVector
            drawSlot = not drawSlot
            debugMsg("i: " + str(i) + ", cursor: " + str(cursor))
        # (We don't modify the path so we don't need to close it)

    def effect(self):
        self.side  = self.options.side
        self.numtabs  = self.options.numtabs
        self.numslots  = self.options.numslots
        self.thickness = self.svg.unittouu(str(self.options.thickness) + self.options.units)
        self.tSlotNutHeight = self.svg.unittouu(str(self.options.tSlotNutHeight) + self.options.units)
        self.tSlotNutWidth = self.svg.unittouu(str(self.options.tSlotNutWidth) + self.options.units)
        self.tSlotScrewWidth = self.svg.unittouu(str(self.options.tSlotScrewWidth) + self.options.units)
        self.tSlotScrewDepth = self.svg.unittouu(str(self.options.tSlotScrewDepth) + self.options.units)
        self.tSlotHoleDiameter = self.svg.unittouu(str(self.options.tSlotHoleDiameter) + self.options.units)
        self.kerf = self.svg.unittouu(str(self.options.kerf) + self.options.units)
        self.units = self.options.units
        self.featureStart = self.options.featureStart
        self.featureEnd = self.options.featureEnd
        self.flipside = self.options.flipside
        self.activetab = self.options.activetab

        for id, node in self.svg.selected.items():
            debugMsg(node)
            debugMsg('1')
            if node.tag == inkex.addNS('path','svg'):
                p = list(node.path.to_superpath().to_segments())
                debugMsg('2')
                debugMsg(p)

                lines = linesNumber(p)
                lineNum = self.side % lines
                debugMsg(lineNum)

                newPath = []
                if self.activetab == 'tabpage':
                    newPath = self.draw_tabs(p, lineNum)
                    debugMsg('2')
                    debugMsg(p[:lineNum])
                    debugMsg('3')
                    debugMsg(newPath)
                    debugMsg('4')
                    debugMsg( p[lineNum + 1:])
                    finalPath = p[:lineNum + 1] + newPath + p[lineNum + 2:]
                   
                    debugMsg(finalPath)
                    
                    node.set('d',str(Path(finalPath)))
                elif self.activetab == 'slotpage':
                    newPath = self.draw_slots(p)
     
if __name__ == '__main__':
    QuickJoint().run()

in inx we need to add

            <param name="tSlotNutHeight" type="float" min="0.01" max="99999.00" precision="2" gui-text="t-slot nut height:">1.80</param>
            <param name="tSlotNutWidth" type="float" min="0.01" max="99999.00" precision="2" gui-text="t-slot nut width:">5.50</param>
            <param name="tSlotScrewWidth" type="float" min="0.01" max="99999.00" precision="2" gui-text="t-slot screw width:">3.10</param>
            <param name="tSlotScrewDepth" type="float" min="0.01" max="99999.00" precision="2" gui-text="t-slot screw depth:">10.00</param>


            <param name="tSlotHoleDiameter" type="float" min="0.01" max="99999.00" precision="2" gui-text="t-slot hole diameter:">3.00</param>


    <param name="tSlotEnable" type="bool" gui-text="Use t-slot definitions">false</param>

[JarrettR]

That's looking pretty cool. Complex numbers in this instance are just a convenient way to work with line lengths and angles, instead of fussing around with x/y coordinates and sin/cos.

There's a good summary of t-nuts (probably where I first started using them) in this wonderful guidebook:
https://www.instructables.com/How-to-Build-your-Everything-Really-Really-Fast/

Step 4 discusses them in length, and lays out these important parameters:

1. Fastening length
2. Nut Thickness
3. Nut Width
4. Screw Clearance Depth

This is complicated enough that it might be a good idea to have a whole tab dedicated to just t-nut parameters. Tabs and slots tabs acting as-is, but then the t-slots panel just for all of those numbers and maybe a good description of what they do. I'm happy to help you tweak that.