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fix(fixTJunctions): fixes issues with fixTJunctions (#63)
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* fixes internals for some corner cases of fixTJunctions (see jscad/scad-api#26)
* adds tests
* split out fixTJunction & cleanup
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@kaosat-dev
kaosat-dev committed Nov 3, 2017
1 parent 84360bd commit 78c5102
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Showing 3 changed files with 581 additions and 318 deletions.
328 changes: 10 additions & 318 deletions src/CSG.js
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ const CAG = require('./CAG') // FIXME: circular dependency !

const Properties = require('./Properties')
const {Connector} = require('./connectors')
const fixTJunctions = require('./utils/fixTJunctions')
// let {fromPolygons} = require('./CSGMakers') // FIXME: circular dependency !

/** Class CSG
Expand Down Expand Up @@ -318,7 +319,7 @@ CSG.prototype = {
// the result is a true expansion of the solid
// If false, returns only the shell
expandedShell: function (radius, resolution, unionWithThis) {
//const {sphere} = require('./primitives3d') // FIXME: circular dependency !
// const {sphere} = require('./primitives3d') // FIXME: circular dependency !
let csg = this.reTesselated()
let result
if (unionWithThis) {
Expand Down Expand Up @@ -732,13 +733,13 @@ CSG.prototype = {
shareds.push(p.shared)
}
})
let numVerticesPerPolygon = new Uint32Array(numpolygons),
polygonSharedIndexes = new Uint32Array(numpolygons),
polygonVertices = new Uint32Array(numpolygonvertices),
polygonPlaneIndexes = new Uint32Array(numpolygons),
vertexData = new Float64Array(numvertices * 3),
planeData = new Float64Array(numplanes * 4),
polygonVerticesIndex = 0
let numVerticesPerPolygon = new Uint32Array(numpolygons)
let polygonSharedIndexes = new Uint32Array(numpolygons)
let polygonVertices = new Uint32Array(numpolygonvertices)
let polygonPlaneIndexes = new Uint32Array(numpolygons)
let vertexData = new Float64Array(numvertices * 3)
let planeData = new Float64Array(numplanes * 4)
let polygonVerticesIndex = 0
for (let polygonindex = 0; polygonindex < numpolygons; ++polygonindex) {
let p = csg.polygons[polygonindex]
numVerticesPerPolygon[polygonindex] = p.vertices.length
Expand Down Expand Up @@ -897,316 +898,8 @@ CSG.prototype = {
return cut3d.projectToOrthoNormalBasis(orthobasis)
},

/*
fixTJunctions:
Suppose we have two polygons ACDB and EDGF:
A-----B
| |
| E--F
| | |
C-----D--G
Note that vertex E forms a T-junction on the side BD. In this case some STL slicers will complain
that the solid is not watertight. This is because the watertightness check is done by checking if
each side DE is matched by another side ED.
This function will return a new solid with ACDB replaced by ACDEB
Note that this can create polygons that are slightly non-convex (due to rounding errors). Therefore the result should
not be used for further CSG operations!
*/
fixTJunctions: function () {
let csg = this.canonicalized()
let sidemap = {}
for (let polygonindex = 0; polygonindex < csg.polygons.length; polygonindex++) {
let polygon = csg.polygons[polygonindex]
let numvertices = polygon.vertices.length
if (numvertices >= 3) // should be true
{
let vertex = polygon.vertices[0]
let vertextag = vertex.getTag()
for (let vertexindex = 0; vertexindex < numvertices; vertexindex++) {
let nextvertexindex = vertexindex + 1
if (nextvertexindex === numvertices) nextvertexindex = 0
let nextvertex = polygon.vertices[nextvertexindex]
let nextvertextag = nextvertex.getTag()
let sidetag = vertextag + '/' + nextvertextag
let reversesidetag = nextvertextag + '/' + vertextag
if (reversesidetag in sidemap) {
// this side matches the same side in another polygon. Remove from sidemap:
let ar = sidemap[reversesidetag]
ar.splice(-1, 1)
if (ar.length === 0) {
delete sidemap[reversesidetag]
}
} else {
let sideobj = {
vertex0: vertex,
vertex1: nextvertex,
polygonindex: polygonindex
}
if (!(sidetag in sidemap)) {
sidemap[sidetag] = [sideobj]
} else {
sidemap[sidetag].push(sideobj)
}
}
vertex = nextvertex
vertextag = nextvertextag
}
}
}
// now sidemap contains 'unmatched' sides
// i.e. side AB in one polygon does not have a matching side BA in another polygon
let vertextag2sidestart = {}
let vertextag2sideend = {}
let sidestocheck = {}
let sidemapisempty = true
for (let sidetag in sidemap) {
sidemapisempty = false
sidestocheck[sidetag] = true
sidemap[sidetag].map(function (sideobj) {
let starttag = sideobj.vertex0.getTag()
let endtag = sideobj.vertex1.getTag()
if (starttag in vertextag2sidestart) {
vertextag2sidestart[starttag].push(sidetag)
} else {
vertextag2sidestart[starttag] = [sidetag]
}
if (endtag in vertextag2sideend) {
vertextag2sideend[endtag].push(sidetag)
} else {
vertextag2sideend[endtag] = [sidetag]
}
})
}

if (!sidemapisempty) {
// make a copy of the polygons array, since we are going to modify it:
let polygons = csg.polygons.slice(0)

function addSide (vertex0, vertex1, polygonindex) {
let starttag = vertex0.getTag()
let endtag = vertex1.getTag()
if (starttag === endtag) throw new Error('Assertion failed')
let newsidetag = starttag + '/' + endtag
let reversesidetag = endtag + '/' + starttag
if (reversesidetag in sidemap) {
// we have a matching reverse oriented side.
// Instead of adding the new side, cancel out the reverse side:
// console.log("addSide("+newsidetag+") has reverse side:");
deleteSide(vertex1, vertex0, null)
return null
}
// console.log("addSide("+newsidetag+")");
let newsideobj = {
vertex0: vertex0,
vertex1: vertex1,
polygonindex: polygonindex
}
if (!(newsidetag in sidemap)) {
sidemap[newsidetag] = [newsideobj]
} else {
sidemap[newsidetag].push(newsideobj)
}
if (starttag in vertextag2sidestart) {
vertextag2sidestart[starttag].push(newsidetag)
} else {
vertextag2sidestart[starttag] = [newsidetag]
}
if (endtag in vertextag2sideend) {
vertextag2sideend[endtag].push(newsidetag)
} else {
vertextag2sideend[endtag] = [newsidetag]
}
return newsidetag
}

function deleteSide (vertex0, vertex1, polygonindex) {
let starttag = vertex0.getTag()
let endtag = vertex1.getTag()
let sidetag = starttag + '/' + endtag
// console.log("deleteSide("+sidetag+")");
if (!(sidetag in sidemap)) throw new Error('Assertion failed')
let idx = -1
let sideobjs = sidemap[sidetag]
for (let i = 0; i < sideobjs.length; i++) {
let sideobj = sideobjs[i]
if (sideobj.vertex0 !== vertex0) continue
if (sideobj.vertex1 !== vertex1) continue
if (polygonindex !== null) {
if (sideobj.polygonindex !== polygonindex) continue
}
idx = i
break
}
if (idx < 0) throw new Error('Assertion failed')
sideobjs.splice(idx, 1)
if (sideobjs.length === 0) {
delete sidemap[sidetag]
}
idx = vertextag2sidestart[starttag].indexOf(sidetag)
if (idx < 0) throw new Error('Assertion failed')
vertextag2sidestart[starttag].splice(idx, 1)
if (vertextag2sidestart[starttag].length === 0) {
delete vertextag2sidestart[starttag]
}

idx = vertextag2sideend[endtag].indexOf(sidetag)
if (idx < 0) throw new Error('Assertion failed')
vertextag2sideend[endtag].splice(idx, 1)
if (vertextag2sideend[endtag].length === 0) {
delete vertextag2sideend[endtag]
}
}

while (true) {
let sidemapisempty = true
for (let sidetag in sidemap) {
sidemapisempty = false
sidestocheck[sidetag] = true
}
if (sidemapisempty) break
let donesomething = false
while (true) {
let sidetagtocheck = null
for (let sidetag in sidestocheck) {
sidetagtocheck = sidetag
break
}
if (sidetagtocheck === null) break // sidestocheck is empty, we're done!
let donewithside = true
if (sidetagtocheck in sidemap) {
let sideobjs = sidemap[sidetagtocheck]
if (sideobjs.length === 0) throw new Error('Assertion failed')
let sideobj = sideobjs[0]
for (let directionindex = 0; directionindex < 2; directionindex++) {
let startvertex = (directionindex === 0) ? sideobj.vertex0 : sideobj.vertex1
let endvertex = (directionindex === 0) ? sideobj.vertex1 : sideobj.vertex0
let startvertextag = startvertex.getTag()
let endvertextag = endvertex.getTag()
let matchingsides = []
if (directionindex === 0) {
if (startvertextag in vertextag2sideend) {
matchingsides = vertextag2sideend[startvertextag]
}
} else {
if (startvertextag in vertextag2sidestart) {
matchingsides = vertextag2sidestart[startvertextag]
}
}
for (let matchingsideindex = 0; matchingsideindex < matchingsides.length; matchingsideindex++) {
let matchingsidetag = matchingsides[matchingsideindex]
let matchingside = sidemap[matchingsidetag][0]
let matchingsidestartvertex = (directionindex === 0) ? matchingside.vertex0 : matchingside.vertex1
let matchingsideendvertex = (directionindex === 0) ? matchingside.vertex1 : matchingside.vertex0
let matchingsidestartvertextag = matchingsidestartvertex.getTag()
let matchingsideendvertextag = matchingsideendvertex.getTag()
if (matchingsideendvertextag !== startvertextag) throw new Error('Assertion failed')
if (matchingsidestartvertextag === endvertextag) {
// matchingside cancels sidetagtocheck
deleteSide(startvertex, endvertex, null)
deleteSide(endvertex, startvertex, null)
donewithside = false
directionindex = 2 // skip reverse direction check
donesomething = true
break
} else {
let startpos = startvertex.pos
let endpos = endvertex.pos
let checkpos = matchingsidestartvertex.pos
let direction = checkpos.minus(startpos)
// Now we need to check if endpos is on the line startpos-checkpos:
let t = endpos.minus(startpos).dot(direction) / direction.dot(direction)
if ((t > 0) && (t < 1)) {
let closestpoint = startpos.plus(direction.times(t))
let distancesquared = closestpoint.distanceToSquared(endpos)
if (distancesquared < (EPS * EPS)) {
// Yes it's a t-junction! We need to split matchingside in two:
let polygonindex = matchingside.polygonindex
let polygon = polygons[polygonindex]
// find the index of startvertextag in polygon:
let insertionvertextag = matchingside.vertex1.getTag()
let insertionvertextagindex = -1
for (let i = 0; i < polygon.vertices.length; i++) {
if (polygon.vertices[i].getTag() === insertionvertextag) {
insertionvertextagindex = i
break
}
}
if (insertionvertextagindex < 0) throw new Error('Assertion failed')
// split the side by inserting the vertex:
let newvertices = polygon.vertices.slice(0)
newvertices.splice(insertionvertextagindex, 0, endvertex)
let newpolygon = new Polygon(newvertices, polygon.shared /* polygon.plane */)

// FIX
// calculate plane with differents point
if (isNaN(newpolygon.plane.w)) {
let found = false,
loop = function (callback) {
newpolygon.vertices.forEach(function (item) {
if (found) return
callback(item)
})
}

loop(function (a) {
loop(function (b) {
loop(function (c) {
newpolygon.plane = Plane.fromPoints(a.pos, b.pos, c.pos)
if (!isNaN(newpolygon.plane.w)) {
found = true
}
})
})
})
}
// FIX

polygons[polygonindex] = newpolygon

// remove the original sides from our maps:
// deleteSide(sideobj.vertex0, sideobj.vertex1, null);
deleteSide(matchingside.vertex0, matchingside.vertex1, polygonindex)
let newsidetag1 = addSide(matchingside.vertex0, endvertex, polygonindex)
let newsidetag2 = addSide(endvertex, matchingside.vertex1, polygonindex)
if (newsidetag1 !== null) sidestocheck[newsidetag1] = true
if (newsidetag2 !== null) sidestocheck[newsidetag2] = true
donewithside = false
directionindex = 2 // skip reverse direction check
donesomething = true
break
} // if(distancesquared < 1e-10)
} // if( (t > 0) && (t < 1) )
} // if(endingstidestartvertextag === endvertextag)
} // for matchingsideindex
} // for directionindex
} // if(sidetagtocheck in sidemap)
if (donewithside) {
delete sidestocheck[sidetag]
}
}
if (!donesomething) break
}
let newcsg = CSG.fromPolygons(polygons)
newcsg.properties = csg.properties
newcsg.isCanonicalized = true
newcsg.isRetesselated = true
csg = newcsg
} // if(!sidemapisempty)
sidemapisempty = true
for (let sidetag in sidemap) {
sidemapisempty = false
break
}
if (!sidemapisempty) {
// throw new Error("!sidemapisempty");
console.log('!sidemapisempty')
}
return csg
return fixTJunctions(CSG.fromPolygons, this)
},

toTriangles: function () {
Expand Down Expand Up @@ -1248,7 +941,6 @@ CSG.prototype = {
}
}


/** Construct a CSG solid from a list of `Polygon` instances.
* @param {Polygon[]} polygons - list of polygons
* @returns {CSG} new CSG object
Expand Down

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