src/conway.civet

@@ -19,28 +19,28 @@ icosahedron: Polyhedron :=
           [3,2,11], [3,10,2], [3,6,10], [3,7,6], [3,11,7]]
    xyz: [[0,ihp,1], [0,-ihp,1], [0,ihp,-1], [0,-ihp,-1],
          [ihp,1,0], [-ihp,1,0], [ihp,-1,0], [-ihp,-1,0],
-         [1,0,ihp], [1,0,-ihp], [-1,0,ihp], [-1,0,-ihp]]
+         [1,0,ihp], [-1,0,ihp], [1,0,-ihp], [-1,0,-ihp]]
 polyCache: Record<Notation, Polyhedron> :=
    '': face: [], xyz: []
    T:
-      face: [[0,1,2], [0,2,3], [0,3,1], [1,3,2]]
+      face: [[0,2,1], [0,3,2], [0,1,3], [1,2,3]]
       xyz: [[1,1,1], [1,-1,-1], [-1,1,-1], [-1,-1,1]]
    O:
-      face: [[0,1,2], [0,2,3], [0,3,4], [0,4,1],
-             [1,4,5], [1,5,2], [2,5,3], [3,5,4]]
+      face: [[0,2,1], [0,3,2], [0,4,3], [0,1,4],
+             [1,5,4], [1,2,5], [2,3,5], [3,4,5]]
       xyz: [[0,0,rt2], [rt2,0,0], [0,rt2,0], [-rt2,0,0], [0,-rt2,0], [0,0,-rt2]]
    C:
-      face: [[3,0,1,2], [3,4,5,0], [0,5,6,1], [1,6,7,2], [2,7,4,3], [5,4,7,6]]
+      face: [[0,3,2,1], [0,5,4,3], [0,1,6,5], [1,2,7,6], [2,3,4,7], [4,5,6,7]]
       xyz: [[rth,rth,rth], [-rth,rth,rth], [-rth,-rth,rth], [rth,-rth,rth],
             [rth,-rth,-rth], [rth,rth,-rth], [-rth,rth,-rth], [-rth,-rth,-rth]]
    I: icosahedron
-   D: geomDual(icosahedron)
+   D: geomDual icosahedron
 
 export function generateVRML(notation: Notation): string
    outputVRML notation, generatePoly notation
 
 function generatePoly(notation: Notation): Polyhedron
-   getStandardPoly standardize notation
+   getStandardPoly inform standardize notation
 
 function getStandardPoly(notation: Notation): Polyhedron
    if notation in polyCache then return polyCache[notation]
@@ -48,23 +48,37 @@ function getStandardPoly(notation: Notation): Polyhedron
    parent := getStandardPoly rest
    // may have created what we want by side effect
    if notation in polyCache then return polyCache[notation]
-   dispatch op, Number(arg or 0), parent, notation  // will do the caching
+   dispatch op, arg, parent, notation  // will do the caching
 
 // Convenience tuple maker
 function ð<Tup extends unknown[]>(...arg: Tup): Tup arg
 
+// Note we now allow numeric arguments on all of the basic operations,
+// kis/truncate, join/ambo, and gyro/snub. Likely some of the operations
+// we are taking as composite could have reasonable numeric versions, but
+// there didn't seem to be any sensible way to propagate such an argument
+// to the operations in their rewrites. In other words, the numeric-limited
+// operations may not be composite, or at least not in the same way. So
+// we have just left them as applying throughout the polyhedron.
 rawStandardizations :=
    P4$: 'C', A3$: 'O', Y3$: 'T',                       // Seed synonyms
    e: 'aa', b: 'ta', o: 'jj', m: 'kj',                 // abbreviations
-   [String.raw`t(\d*)`]: 'd$1d', j: 'dad', s: 'dgd',  // dual operations
-   dd: '', ad: 'a', gd: 'g',                          // absorption of duals
+   [String.raw`t(\d*)`]: 'dk$1d',
+   [String.raw`a(\d*)`]: 'dj$1d',                      // dual operations
+   [String.raw`s(\d*)`]: 'dg$1d',
+   dd: '', rr: '', jd: 'j', gd: 'rgr',                 // absorption rules
+   rd: 'dr',  // these commute; others? If so, move 'r' in to cancel w/ seed
    // Remainder are all simplifications/unique selections for seeds:
-   aY: 'A', dT: 'T', gT: 'D', aT: 'O', dC: 'O', dO: 'C',
-   dI: 'D', dD: 'I', aO: 'aC', aI: 'aD', gO: 'gC', gI: 'gD'
+   aY: 'A', dT: 'T', gT: 'D', jT: 'C', dC: 'O', dO: 'C',
+   dI: 'D', dD: 'I', rO: 'O', rC: 'C', rI: 'I', rD: 'D',
+   jO: 'jC', jI: 'jD', gO: 'gC', gI: 'gD'
 standardizations :=
    (ð RegExp(pat, 'g'), rep for pat, rep in rawStandardizations)
 
 function standardize(notation: Notation): Notation
+   lastNotation .= ''
+   while lastNotation != notation  // iterate in case of rdrd, e.g.
+      lastNotation = notation
       for [pat, rep] of standardizations
          notation = notation.replace(pat, rep)
    notation
@@ -80,6 +94,7 @@ function orb(r: number, n: number,
 
 seeds :=
    P: (n: number) => // Prism
+         unless n then n = 3
          theta := tau/n
          halfEdge := Math.sin theta/2
          xyz := orb(1, n, halfEdge) ++ orb(1, n, -halfEdge)
@@ -89,6 +104,7 @@ seeds :=
             face.push [i, ip1, ip1+n, i+n]
          {face, xyz}
    A: (n: number) => // Antiprism
+         unless n then n = 4
          theta := tau/n
          halfHeight .= Math.sqrt
             1 - 4/(4 + 2*Math.cos(theta/2) - 2*Math.cos(theta))
@@ -98,20 +114,24 @@ seeds :=
          halfHeight /= f
          faceRadius /= f
          xyz := orb(faceRadius, n, halfHeight)
-	        ++ orb(faceRadius, n, halfHeight, 0.5)
+	        ++ orb(faceRadius, n, -halfHeight, 0.5)
          face := [[n-1..0], [n...2*n]] // top and bottom
          for i of [0...n]
             face.push [i, (i+1)%n, i+n]
             face.push [i, i+n, n + (n+i-1)%n]
          {face, xyz}
    Y: (n: number) => // pYramid
+         unless n then n = 4
          // Canonical solution by Intelligenti Pauca and Ed Pegg, see
          // https://math.stackexchange.com/questions/2286628/canonical-pyramid-polynomials
          theta := tau/n
          c := Math.cos theta/2
          baseRadius := Math.sqrt 2/(c*(1+c))
-         xyz := orb baseRadius, n, Math.tan theta/4
-         xyz.push [0, 0, -1/Math.tan theta/4]
+         depth := Math.sqrt (1-c)/(1+c)
+         height := 2*Math.sqrt 1/(1 - c*c)
+         xyz := orb baseRadius, n, depth
+         edgeMid2 := add xyz[0], xyz[1]
+         xyz.push [0, 0, depth-height]
          face := ([i, (i+1)%n, n] for i of [0...n])
          face.unshift [n-1..0]
          {face, xyz}
@@ -120,29 +140,94 @@ type SeedOp = keyof typeof seeds
 // Syntactic sugar to deal with weird TypeScript typing:
 operator æ<T>(A: T[], i: number) A.at(i) as T
 
-transforms :=
-   k: (P: Polyhedron, n: number, notation: string): Polyhedron =>  // kis[n]
-         // aka "elevate" -- add a pyramid on each (n-sided) face
-         centers := faceCenters P
-         xyz := P.xyz.slice()
+function kisjoin(P: Polyhedron, notation: string,
+                 digits: string, join: boolean): Polyhedron
+   // kis and join are closely related operations. Both of them add a
+   // pyramid on a selection of faces; join then further deletes any
+   // _original_ edge bordered by two _new_ triangles, producing a quad.
+   // Faces are selected by their numbers of sides, using the given digits.
+   // If there are none, all faces are used. Otherwise, the digits are turned
+   // into a list of numbers by breaking after every digit except as needed
+   // to prevent leading 0s or isolated 1s or 2s (since no face has one or
+   // two sides); this way you can list any subset of the numbers 3 - 32,
+   // which is plenty.
+   // The operation is then applied just to faces with the numbers of edges on
+   // the list. e.g. k3412 will add pyramids to the triangles, quads, and
+   // dodecagon faces.
+   allowed := parseSides digits
+   // first collect a directory from face indices to new vertex numbers
+   nextVertex .= P.xyz.length
+   newVixes :=
+      for f of P.face
+         !digits or f.length is in allowed ? nextVertex++ : 0
+   if nextVertex is P.xyz.length then return P  // nothing to do
+   xyz := P.xyz ++ faceCenters(P).filter (f,ix) => newVixes[ix]
    face: Face[] := []
    for each f, ix of P.face
-            if n is 0 or f.length is n
-               v := xyz.length
-               xyz.push centers[ix]
-               for each j of [0...f.length]
-                  face.push [v, f æ (j-1), f[j]]
-            else face.push f.slice()
+      v := newVixes[ix]
+      if v is 0
+         face.push f.slice()
+         continue
+      // Add the pyramid, possibly eliding edges:
+      for each w, jx of f
+         pw := f æ (jx-1)
+         neighbor .= 0
+         if join
+            neighbor = P.face.findIndex (g, gx) =>
+                          gx !== ix and w is in g and pw is in g
+         if join and newVixes[neighbor]  // elide this edge
+            if pw < w // avoid adding same face twice
+               face.push [v, pw, newVixes[neighbor], w]
+         else face.push [v, pw, w]
    adjustXYZ({face, xyz}, notation, 3)
+
+enum Gyway
+  FromCenter
+  AlongEdge
+function gyropel(P: Polyhedron, notation: string,
+                 digits: string, ...ways: Gyway[]): Polyhedron
+   // gyro and propellor are closely related operations. Both of them add new
+   // vertices one third of the way along each edge of each face selected
+   // by the digits argument (see kisjoin). They then differ in what edges
+   // are drawn to the new vertices. In gyro, another new vertex is added
+   // at the center of each face and connected to each of them; in propellor,
+   // they are just connected in sequence. For completeness, we also allow
+   // both at the same time, which is equivalent to propellor followed by kis
+   // just on the new rotated faces.
+   // TO BE IMPLEMENTED
+
+function parseSides(digits: string): number[]
+   unless digits return []
+   tooSmall := ['1', '2']
+   last := digits.length - 1
+   return := []
+   current .= ''
+   pos .= 0
+   while pos <= last
+      current += digits[pos++]
+      nextDigit := digits[pos]
+      if (current is in tooSmall
+          or nextDigit is '0'
+          or pos == last and nextDigit is in tooSmall)
+         continue
+      return.value.push parseInt current
+      current = ''
+
+transforms :=
+   k: (P: Polyhedron, notation: string, digits: string) =>  // kis[n]
+      kisjoin P, notation, digits, false
+   j: (P: Polyhedron, notation: string, digits: string) =>  // join
+      kisjoin P, notation, digits, true
+
 type TransformOp = keyof typeof transforms
 
-function dispatch(op: string, n: number,
+function dispatch(op: string, digits: string,
                   P: Polyhedron, notation: string): Polyhedron
    return .= P
    if op in seeds
-      return = seeds[op as SeedOp] n
+      return = seeds[op as SeedOp] Number(digits) or 0
    else if op in transforms
-      return = transforms[op as TransformOp] P, n, notation
+      return = transforms[op as TransformOp] P, notation, digits
    polyCache[notation] = return.value
 
 function topoDual(P: Polyhedron): Polyhedron
@@ -151,34 +236,67 @@ function topoDual(P: Polyhedron): Polyhedron
    // in some way.
    face:
       for v of [0...P.xyz.length]
-         infaces :=
+         infaces :=  // gather labeled list of faces contining v
             for f, index of P.face
                unless f.includes v continue
                ð f, index
          start := infaces[0][1];
          current .= start
+         newface := []
          do
            verts := P.face[current]
            preV := verts æ (verts.indexOf(v)-1)
            nextIx := infaces.findIndex ([face, label]) =>
               label !== current and face.includes preV
            current = infaces[nextIx][1]
+           newface.push current
+           if newface.length > infaces.length
+              console.error 'In topoDual: Malformed polyhedron', P
+              break
          until current is start
+         newface
    xyz:
       Array(P.face.length).fill([0,0,0]) // warning, every vertex is ===
 
 function geomDual(P: Polyhedron): Polyhedron
-   // Takes the vertices of the dual to be the face centers of P
-   // all scaled so that the midpoint of the first edge is unit distance
-   // from the origin
-   return := topoDual(P)
-   newVertices := faceCenters(P)
-   aface := return.value.face[0]
-   mid2 := add newVertices[aface[0]], newVertices[aface[1]]
-   factor := 2/mag mid2
-   for each v of newVertices
-      scale(v, factor)
-   return.value.xyz = newVertices
+   return := topoDual P
+   return.value.xyz = approxDualVertices P
+
+function approxDualVertices(P: Polyhedron): XYZ[]
+   P.face.map (f) => approxDualVertex f, P.xyz
+
+operator dot(v: number[], w: number[])
+   v.reduce (l,r,i) => l + r*w[i], 0
+
+function approxDualVertex(f: Face, v: XYZ[]): XYZ
+   // For each edge of f, there is a plane containing it perpendicular
+   // to the line joining the origin to its nearest approach to the origin.
+   // This function returns the point closest to being on all of those planes
+   // (in the least-squares sense).
+   // This method seems to work well when the neighborhood of f is convex,
+   // and very poorly otherwise. So it probably would not provide any better
+   // canonicalization than other methods of approximating the dual.
+   normals := (tangentPoint(v[f æ (i-1)], v[f[i]]) for i of [0...f.length])
+   sqlens := normals.map mag2
+   columns := (normals.map(&[i]) for i of [0..2])
+   target := (columns[i] dot sqlens for i of [0..2]) as XYZ
+   CMsource := (for c of [0..2]
+        (columns[r] dot columns[c] for r of [0..2])) as [XYZ, XYZ, XYZ]
+   cramerD := det ...CMsource
+   if Math.abs(cramerD) < 1e-6
+      console.error `Face ${f} of ${v.map (p) => '['+p+']'} ill conditioned`
+      return [0, 0, 0]
+   [ det(target,CMsource[1],CMsource[2])/cramerD,
+     det(CMsource[0],target,CMsource[2])/cramerD,
+     det(CMsource[0],CMsource[1],target)/cramerD ]
+
+function det(a: XYZ, b: XYZ, c:XYZ)
+   a[0]*b[1]*c[2] + a[1]*b[2]*c[0] + a[2]*b[0]*c[1]
+      - a[2]*b[1]*c[0] - a[1]*b[0]*c[2] - a[0]*b[2]*c[1]
+
+function tangentPoint(v: XYZ, w: XYZ) // closest point on vw to origin
+   d := sub w,v
+   sub v, scale d, d dot v / mag2 d
 
 function faceCenters(P: Polyhedron): XYZ[]
    for each face of P.face
@@ -209,12 +327,21 @@ function accumulate(basket: XYZ, egg: XYZ)
    basket[2] += egg[2]
    basket
 
+function diminish(basket: XYZ, egg: XYZ)
+   basket[0] -= egg[0]
+   basket[1] -= egg[1]
+   basket[2] -= egg[2]
+   basket
+
 function copy(a: XYZ)
    ð a[0], a[1], a[2]
 
 function add(a: XYZ, b: XYZ)
    accumulate copy(a), b
 
+function sub(a: XYZ, b: XYZ)
+   diminish copy(a), b
+
 function mag2(a: XYZ)
    a[0]*a[0] + a[1]*a[1] + a[2]*a[2]
 
@@ -227,6 +354,13 @@ function scale(subject: XYZ, by: number)
    subject[2] *= by
    subject
 
+// Feedback
+
+function inform(x: string)
+   $('input[name="inform"]').val(x)
+   x
+
+
 // VRML97 generation
 
 function outputVRML(notation: Notation, P: Polyhedron): string
@@ -235,17 +369,26 @@ function outputVRML(notation: Notation, P: Polyhedron): string
 Group { children [
    WorldInfo { # Generated by GTW's reimplementation of GWH's Conway script.
       title "${notation}   ${stats P}"
-      info "Generated by GTW's Conway-notation script inspired by GWH's."
-      info "By using this script, you agree that this image is released"
-      info "into the public domain, although you are requested to cite"
-      info "George Hart's Encyclopedia of Polyhedra as the source." }
+      info "Generated by GTW's Conway-notation script inspired by GWH's.
+By using this script, you agree that this image is released
+into the public domain, although you are requested to cite
+George Hart's Encyclopedia of Polyhedra as the source." }
    Background {
       groundColor [ .2 .5 1 ] # light blue
-      skycolor [ .2 .5 1] }
+      skyColor    [ .2 .5 1 ] }
    NavigationInfo { type [ "EXAMINE" ] }
    DirectionalLight {direction -.5 -1  1 intensity 0.75}
    DirectionalLight {direction  .5  1 -1 intensity 0.75}
-   ${polyVRML P, colorScheme()} ] }
+   ${polyVRML P, colorScheme()}
+   Shape {
+      appearance Appearance {
+         material Material {
+            diffuseColor 0 0 0 } }
+      geometry IndexedLineSet {
+         coord ${useVerts}
+         coordIndex [
+            ${edgeIndices P} ] } }
+   ${showDual() ? polyVRML geomDual(P), '0.5 0.5 0.5' : ''} ] }
    ```
 
 function stats(P: Polyhedron): string
@@ -274,15 +417,19 @@ function polyVRML(P: Polyhedron, color: string): string
          material Material {
             diffuseColor ${color or colorBySides part[0].length} } }
       geometry IndexedFaceSet {
+         ccw FALSE
          coord ${emittedCoords ? useVerts : (emittedCoords = defVerts P.xyz)}
          coordIndex [
             ${part.map(.join ', ').join(", -1,\n            ")}, -1 ] }}`
    shapes.join "\n"
 
-function colorScheme()
+function colorScheme
    button := document.getElementsByName('color')[0] as HTMLInputElement
    button.checked ? '1 1 1' : ''
 
+function showDual
+   false
+
 faceColors: Record<number, string> :=
    3: '0.9 0.3 0.3' // red
    4: '0.4 0.4 1.0' // blue
@@ -297,4 +444,15 @@ faceColors: Record<number, string> :=
 function colorBySides(n: number)
    if n in faceColors
       return faceColors[n]
-   return '0.5 0.5 0.5' // gray
+   '0.5 0.5 0.5' // gray
+
+function filtmap<T,U>(A: T[], m: (e:T, i: number, arr: T[]) => U)
+   A.map(m).filter (e) => !!e
+
+function edgeIndices(P: Polyhedron)
+   sep := ",\n            "
+   filtmap(P.face, (thisf) =>
+         filtmap(thisf, (v, ix, f) =>
+            preV := f æ (ix-1)
+            preV < v ? `${preV}, ${v}, -1` : '').join sep)
+      .join sep

src/giveAwrl.civet

@@ -45,7 +45,7 @@ function makeBrowser(url: string, width: string, height: string)
       browser3D.baseURL = url
       scene := await browser3D.createX3DFromString text
       browser3D.replaceWorld scene
-   canvas
+   {canvas, browser3D}
 
 // Put eye icons after all of the eligible links
 links := $('a').filter -> knownExtensions.test @.getAttribute('href') ?? ''
@@ -79,7 +79,7 @@ links.after ->
             overImg := floatLike and floatLike.tagName is 'IMG'
             width := overImg ? ($(floatLike).width() + 'px') : '150px'
             height := overImg ? ($(floatLike).height() + 'px') : '150px'
-            canvas := await makeBrowser url, width, height
+            {canvas} := await makeBrowser url, width, height
             if float
                canvas.style.float = float
             if overImg
@@ -102,6 +102,9 @@ links.after ->
             $(eye).css 'text-decoration', 'none'
             $(eye.lastElementChild as Element).hide()
 
+let conwayBrowser: any
+madeConway .= false
+
 // See if we are on George Hart's Conway-notation generator page
 inputs := $('input[type="button"][value="Generate"][onclick="viewVRML()"]')
 if inputs.length is 1
@@ -114,12 +117,19 @@ if inputs.length is 1
          notation := $('input[name="notation"]').val()
          unless notation then return
          vrml := conway.generateVRML notation.toString()
-         viewerSpan := $(`<span>${vrml}</span>`)
-         viewerSpan.css 'float', 'left'
-         $('form[name="input"]').first().before viewerSpan
+         unless madeConway
+            {canvas, browser3D} := await makeBrowser '', '250px', '250px'
+            conwayBrowser = browser3D
+            canvas.style.float = 'left'
+            canvas.style.marginRight = '1em'
+            $('form[name="input"]').first().before canvas
+            madeConway = true
+         scene := await conwayBrowser.createX3DFromString vrml
+         conwayBrowser.replaceWorld scene
 
 // See if we are on George Hart's prism generator page
 prisms := $('input[type="button"][value="View"][onclick="ViewVRML()"]')
 if prisms.length is 1
    // Seems so, fix the generator
    console.log 'Need to fix the prism generator'
+