feat: support Viewpoints, translating PerspectiveCamera (#21)

Reviewed-on: #21
Co-authored-by: Glen Whitney <glen@studioinfinity.org>
Co-committed-by: Glen Whitney <glen@studioinfinity.org>

README.md

@@ -13,9 +13,11 @@ VRML 1.0. Overall, it recognizes and converts
   * Title, SceneInfo, BackgroundColor, and View "Info" nodes [this node type
     was removed in VRML97].
   * All Light nodes
-  * Grouping nodes including Transform, Separator, Group, Switch, and WWWAnchor
+  * PerspectiveCamera nodes (converted into Viewpoint nodes)
+  * Grouping nodes including Separator, Group, Switch, and WWWAnchor
+  * Interprets a Switch named "Cameras" (by a DEF) as a list of Viewpoints
   * ShapeHints
-  * Rotations and Translations
+  * Transformation nodes including Translation, Rotation, Scale, and Transform
   * All shape nodes including Cube, Cone, Cylinder, Sphere, IndexedFaceSet,
     IndexedLineSet, PointSet, Coordinate3, and Normal
   * All material nodes including Material, TextureCoordinate2, and Texture2

package.json5

@@ -1,6 +1,6 @@
 {
   name: 'vrml1to97',
-  version: '0.3.1',
+  version: '0.4.0',
   description: 'JavaScript converter from VRML 1 to VRML97',
   scripts: {
     test: 'echo "Error: no test specified" && exit 1',

src/index.civet

@@ -91,6 +91,7 @@ function addWorldParameter(name: string, value: string, tree: Tree): void
 matches := (str: string, pat: RegExp) => pat.test(str)
 operator matches
 GroupNode := /(?:Transform)?Separator|Group|Switch|WWWAnchor/
+TransformNode := /^(?:Rotation|Scale|Transform|Translation)$/
 SetNode := /IndexedFaceSet|IndexedLineSet|PointSet/
 LightNode := /Light$/
 
@@ -155,22 +156,39 @@ function parse(stream: Lexer, tree: DefTree = {}): DefTree
                continue
             currentDefinition = next.value
             held = filtered stream
+            // Special case from VRML 1: DEF Cameras Switch { ... }
+            // needs to be hoisted to a list of viewpoints at this level
+            if currentDefinition is 'Cameras' and held?.value is 'Switch'
+               held = filtered stream
+               unless held?.type is 'obrace'
+                  console.error
+                     `DEF Cameras Switch followed by ${held?.value}, ignoring`
+                  continue
+               {children, ...context} := tree
+               subTree := parse stream, context
+               addChild renderList(subTree.children), tree
+               held = filtered stream
+               continue
             if held?.type is 'word'
                clause := `DEF ${currentDefinition}`
                role .= held.value
                switch role
                   matches GroupNode
                      role = 'Child'
-                  'ShapeHints'
-                     role = 'Dummy' // will fill in when we parse the ShapeHints
+                  matches TransformNode
+                     role = 'Transform'
                   'Coordinate3'
                      role = 'Coordinate'
-                  'TextureCoordinate2'
-                     role = 'TextureCoordinate'
-                  'Texture2'
-                     role = 'Texture'
                   /Cube|Cone|Cylinder|Sphere/
                      role = 'Shape'
+                  'PerspectiveCamera'
+                     role = 'Viewpoint'
+                  'ShapeHints'
+                     role = 'Dummy' // will fill in when we parse the ShapeHints
+                  'Texture2'
+                     role = 'Texture'
+                  'TextureCoordinate2'
+                     role = 'TextureCoordinate'
                   matches SetNode
                      role = 'Shape'
                   matches LightNode
@@ -193,6 +211,19 @@ function parse(stream: Lexer, tree: DefTree = {}): DefTree
                      addChild clause, tree
                   'Shape'
                      addShape clause, [], tree
+                  'Transform'
+                     // VRML97 doesn't allow just the transform part of
+                     // a Transform to be USEd (the whole node must be), so
+                     // we have to recreate the transform. FIXME: dedupe code
+                     content := known[next.value][1..]
+                     {children, ...context} := tree
+                     restOfTree := parse stream, context
+                     if remainingKids := restOfTree.children
+                        newChild := `Transform {\n   ${renderList content}\n   `
+                           + `children [\n      ${renderList remainingKids}`
+                           + "] }\n"
+                        addChild newChild, tree
+                     return tree
                   {}
                      mergeTree role, tree
                   else
@@ -203,20 +234,30 @@ function parse(stream: Lexer, tree: DefTree = {}): DefTree
          {ht: 'word', nt: 'obrace'}
             switch held.value
                matches GroupNode
-                  parent :=
-                     held.value.endsWith('Separator') ? 'Transform' : 'Group'
-                  {children, Translation, Rotation, ...context} := tree
+                  {children, ...context} := tree
                   subTree := parse stream, context
                   if newKids := subTree.children
-                     newChild .= `${parent} {\n   `
-                     if 'Rotation' in subTree
-                        newChild += renderList subTree.Rotation
-                        newChild += "\n   "
-                     if 'Translation' in subTree
-                        newChild += renderList subTree.Translation
-                        newChild += "\n   "
-                     newChild += `children [\n      ${renderList newKids} ] }\n`
+                     newChild .= ''
+                     if held.value is 'Switch'
+                        newChild = "Switch {\n  "
+                        if 'whichChoice' in subTree
+                           newChild += `whichChoice ${subTree.whichChoice[0]}\n   `
+                        newChild += `choice [\n     ${renderList newKids} ] }\n`
+                     else newChild =
+                        `Group { children [\n   ${renderList newKids} ] }\n`
                      addChild newChild, tree
+               matches TransformNode
+                  content := toksUntilClose stream
+                  if (lastDefinition
+                      and tree._definitions?[lastDefinition][0] is 'Transform')
+                     tree._definitions[lastDefinition].push ...content
+                  {children, ...context} := tree
+                  restOfTree := parse stream, context
+                  if remainingKids := restOfTree.children
+                     newChild := `Transform {\n   ${renderList content}\n   `
+                        + `children [\n      ${renderList remainingKids} ] }\n`
+                     addChild newChild, tree
+                  return tree // used the rest of the tree, so done
                'ShapeHints'
                   subTree := parse stream
                   hints: Tree := {}
@@ -228,10 +269,14 @@ function parse(stream: Lexer, tree: DefTree = {}): DefTree
                   mergeTree hints, tree
                   if lastDefinition and tree._definitions
                      tree._definitions[lastDefinition] = [hints]
-               'Rotation'
-                  tree.Rotation = toksUntilClose stream
-               'Translation'
-                  tree.Translation = toksUntilClose stream
+               'PerspectiveCamera'
+                  contents := toksUntilClose stream
+                  hasDescription := contents.find (e) =>
+                     e.type?[0] is 'word' and e.value?[0] is 'description'
+                  if lastDefinition and hasDescription is undefined
+                     contents.push type: ['word'], value: ['description']
+                     contents.push type: ['word'], value: [`"${lastDefinition}"`]
+                  addChild {Viewpoint: contents}, tree
                'Coordinate3'
                   tree.Coordinate = toksUntilClose stream
                'Normal'
@@ -298,6 +343,9 @@ function parse(stream: Lexer, tree: DefTree = {}): DefTree
          {ht: 'word', hv: 'creaseAngle', nt: 'number'}
             tree.creaseAngle = [ next.value ]
             held = filtered stream
+         {ht: 'word', hv: 'whichChild'}
+            tree.whichChoice = [ next.value ]
+            held = filtered stream
          else
             console.error 'Ignoring unparseable token', held
             held = next // ignore unknown words