for (i=0; i<20; i++) {
    addLine(i*10,200*Math.sin(2 * Math.PI * i / 20) , (i+1)*10,200*Math.sin(2 * Math.PI * (i+1) / 20));
}

function CubeCuttingOut() {
}
CubeCuttingOut.init = function(formWidget) {
};
CubeCuttingOut.generate = function(documentInterface, file) {
};
CubeCuttingOut.generatePreview = function(documentInterface, iconSize) {
};

CubeCuttingOut.createCuttingOut = function(documentInterface) {
    CubeCuttingOut.size = 10;
    var va = new Array(
            new RVector(0, 0),
            new RVector(0, CubeCuttingOut.size),
            new RVector(CubeCuttingOut.size, CubeCuttingOut.size),
            new RVector(CubeCuttingOut.size, 0)
    );
    var addOperation = new RAddObjectsOperation(false);
    for ( var i = 0; i < va.length; ++i) {
        var lineData = new RLineData(va[i], va[(i + 1) % va.length]);
        var line = new RLineEntity(documentInterface.getDocument(), lineData);
        addOperation.addObject(line);
    }
    return addOperation;
};

CubeCuttingOut.generate = function(documentInterface, file) {
    return CubeCuttingOut.createCuttingOut(documentInterface);
};

CubeCuttingOut.init = function(formWidget) {
    if (!isNull(formWidget)) {
        CubeCuttingOut.widgets = getWidgets(formWidget);
    }
};
// ....
CubeCuttingOut.createCuttingOut = function(documentInterface) {
    var addOperation = new RAddObjectsOperation(false);

    // create squares
    for ( var i = 0; i < 4; ++i) {
        var pos = new RVector(i * CubeCuttingOut.size, 0);
        CubeCuttingOut.createSquare(documentInterface, addOperation, pos);
    }
    var posTop = new RVector(CubeCuttingOut.size * 2, CubeCuttingOut.size);
    CubeCuttingOut.createSquare(documentInterface, addOperation, posTop);
    var posBottom = new RVector(CubeCuttingOut.size * 2, -CubeCuttingOut.size);
    CubeCuttingOut.createSquare(documentInterface, addOperation, posBottom);

    // create plates
    if (CubeCuttingOut.drawPlates) {
        var plates = new Array(
                [ new RVector(4 * CubeCuttingOut.size, 0), 0 ],
                [ new RVector(2 * CubeCuttingOut.size, -3 * CubeCuttingOut.size), 90 ],
                [ new RVector(1 * CubeCuttingOut.size, -4 * CubeCuttingOut.size), 90 ],
                [ new RVector(-2 * CubeCuttingOut.size, -2 * CubeCuttingOut.size), 180 ],
                [ new RVector(-2 * CubeCuttingOut.size, 0), 180 ],
                [ new RVector(1 * CubeCuttingOut.size, 2 * CubeCuttingOut.size), 270 ],
                [ new RVector(0, 3 * CubeCuttingOut.size), 270 ]
        );
        for ( var i = 0; i < plates.length; ++i) {
            var pos = plates[i][0];
            var angle = RMath.deg2rad(plates[i][1]);
            CubeCuttingOut.createPlate(documentInterface, addOperation, pos, angle);
        }
    }

    return addOperation;
};

CubeCuttingOut.createSquare = function(documentInterface, addOperation, pos) {
    var va = new Array(
            new RVector(0, 0),
            new RVector(0, CubeCuttingOut.size),
            new RVector(CubeCuttingOut.size, CubeCuttingOut.size),
            new RVector(CubeCuttingOut.size, 0)
    );
    for ( var i = 0; i < va.length; ++i) {
        var v1 = va[i].operator_add(pos);
        var v2 = va[(i + 1) % va.length].operator_add(pos);
        var lineData = new RLineData(v1, v2);
        var line = new RLineEntity(documentInterface.getDocument(), lineData);
        addOperation.addObject(line);
    }
};

include("scripts/library.js");
// ....
CubeCuttingOut.init = function(formWidget) {
    if (!isNull(formWidget)) {
        CubeCuttingOut.widgets = getWidgets(formWidget);
    }
};
//...

CubeCuttingOut.generate = function(documentInterface, file) {
    CubeCuttingOut.size = parseInt(CubeCuttingOut.widgets["CubeSize"].text, 10);
    if (isNaN(CubeCuttingOut.size)) {
        // can't parse value as integer, set default size
        CubeCuttingOut.size = 10;
    }

    if (CubeCuttingOut.widgets["DrawPlates"].checked) {
        CubeCuttingOut.drawPlates = true;
    } else {
        CubeCuttingOut.drawPlates = false;
    }

    return CubeCuttingOut.createCuttingOut(documentInterface);
};

CubeCuttingOut.generatePreview = function(documentInterface, iconSize) {
    CubeCuttingOut.size = iconSize / 6;
    CubeCuttingOut.drawPlates = true;
    return CubeCuttingOut.createCuttingOut(documentInterface);
};

/**
 * Copyright (c) 2011-2018 by Andrew Mustun. All rights reserved.
 * 
 * This file is part of the QCAD project.
 *
 * QCAD is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * QCAD is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with QCAD.
 */
// CubeCuttingOut.js
//! [include]
// library.js contains some convenience functions like 'isNull':
include("scripts/library.js");
//! [include]
function CubeCuttingOut() {
    CubeCuttingOut.size = 10;
    CubeCuttingOut.drawPlates = true;
}
//! [init]
CubeCuttingOut.init = function(formWidget) {
    if (!isNull(formWidget)) {
        CubeCuttingOut.widgets = getWidgets(formWidget);
    }
};
//! [init]
//! [generate]
CubeCuttingOut.generate = function(documentInterface, file) {
    CubeCuttingOut.size = parseInt(CubeCuttingOut.widgets["CubeSize"].text, 10);
    if (isNaN(CubeCuttingOut.size)) {
        // can't parse value as integer, set default size
        CubeCuttingOut.size = 10;
    }

    if (CubeCuttingOut.widgets["DrawPlates"].checked) {
        CubeCuttingOut.drawPlates = true;
    } else {
        CubeCuttingOut.drawPlates = false;
    }

    return CubeCuttingOut.createCuttingOut(documentInterface);
};
//! [generate]
//! [generatePreview]
CubeCuttingOut.generatePreview = function(documentInterface, iconSize) {
    CubeCuttingOut.size = iconSize / 6;
    CubeCuttingOut.drawPlates = true;
    return CubeCuttingOut.createCuttingOut(documentInterface);
};
//! [generatePreview]
//! [createCuttingOut]
CubeCuttingOut.createCuttingOut = function(documentInterface) {
    var addOperation = new RAddObjectsOperation(false);

    // create squares
    for ( var i = 0; i < 4; ++i) {
        var pos = new RVector(i * CubeCuttingOut.size, 0);
        CubeCuttingOut.createSquare(documentInterface, addOperation, pos);
    }
    var posTop = new RVector(CubeCuttingOut.size * 2, CubeCuttingOut.size);
    CubeCuttingOut.createSquare(documentInterface, addOperation, posTop);
    var posBottom = new RVector(CubeCuttingOut.size * 2, -CubeCuttingOut.size);
    CubeCuttingOut.createSquare(documentInterface, addOperation, posBottom);

    // create plates
    if (CubeCuttingOut.drawPlates) {
        var plates = new Array(
                [ new RVector(4 * CubeCuttingOut.size, 0), 0 ],
                [ new RVector(2 * CubeCuttingOut.size, -3 * CubeCuttingOut.size), 90 ],
                [ new RVector(1 * CubeCuttingOut.size, -4 * CubeCuttingOut.size), 90 ],
                [ new RVector(-2 * CubeCuttingOut.size, -2 * CubeCuttingOut.size), 180 ],
                [ new RVector(-2 * CubeCuttingOut.size, 0), 180 ],
                [ new RVector(1 * CubeCuttingOut.size, 2 * CubeCuttingOut.size), 270 ],
                [ new RVector(0, 3 * CubeCuttingOut.size), 270 ]
        );
        for ( var i = 0; i < plates.length; ++i) {
            var pos = plates[i][0];
            var angle = RMath.deg2rad(plates[i][1]);
            CubeCuttingOut.createPlate(documentInterface, addOperation, pos, angle);
        }
    }

    return addOperation;
};
//! [createCuttingOut]
//! [createSquare]
CubeCuttingOut.createSquare = function(documentInterface, addOperation, pos) {
    var va = new Array(
            new RVector(0, 0),
            new RVector(0, CubeCuttingOut.size),
            new RVector(CubeCuttingOut.size, CubeCuttingOut.size),
            new RVector(CubeCuttingOut.size, 0)
    );
    for ( var i = 0; i < va.length; ++i) {
        var v1 = va[i].operator_add(pos);
        var v2 = va[(i + 1) % va.length].operator_add(pos);
        var lineData = new RLineData(v1, v2);
        var line = new RLineEntity(documentInterface.getDocument(), lineData);
        addOperation.addObject(line);
    }
};
//! [createSquare]
CubeCuttingOut.createPlate = function(documentInterface, addOperation, pos, angle) {
    var plateSize = CubeCuttingOut.size / 7;
    var off = plateSize * Math.sqrt(2);
    var va = new Array(
            new RVector(0, 0),
            new RVector(off, off),
            new RVector(off, CubeCuttingOut.size - off),
            new RVector(0, CubeCuttingOut.size)
    );
    for ( var i = 0; i < va.length; ++i) {
        var v1 = va[i].operator_add(pos);
        v1 = v1.rotate(angle);
        var v2 = va[(i + 1) % va.length].operator_add(pos);
        v2 = v2.rotate(angle);
        var lineData = new RLineData(v1, v2);
        var line = new RLineEntity(documentInterface.getDocument(), lineData);
        addOperation.addObject(line);
    }
};

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>Form</class>
 <widget class="QWidget" name="Form">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>239</width>
    <height>76</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>Form</string>
  </property>
  <layout class="QFormLayout" name="formLayout">
   <item row="0" column="0">
    <widget class="QLabel" name="label">
     <property name="text">
      <string>Cube size:</string>
     </property>
    </widget>
   </item>
   <item row="0" column="1">
    <widget class="QLineEdit" name="CubeSize">
     <property name="text">
      <string>10</string>
     </property>
    </widget>
   </item>
   <item row="1" column="1">
    <widget class="QCheckBox" name="DrawPlates">
     <property name="text">
      <string>Draw plates</string>
     </property>
    </widget>
   </item>
  </layout>
 </widget>
 <resources/>
 <connections/>
</ui>