fix: restore STLExporter (#321)

Author: CodyJasonBennett

src/exporters/STLExporter.d.ts

@@ -0,0 +1,21 @@
+import { Object3D } from 'three'
+
+export interface STLExporterOptionsBinary {
+  binary: true
+}
+
+export interface STLExporterOptionsString {
+  binary?: false
+}
+
+export interface STLExporterOptions {
+  binary?: boolean
+}
+
+export class STLExporter {
+  constructor()
+
+  parse(scene: Object3D, options: STLExporterOptionsBinary): DataView
+  parse(scene: Object3D, options?: STLExporterOptionsString): string
+  parse(scene: Object3D, options?: STLExporterOptions): string | DataView
+}

src/exporters/STLExporter.js

@@ -0,0 +1,166 @@
+import { Vector3 } from 'three'
+
+/**
+ * Usage:
+ *  const exporter = new STLExporter();
+ *
+ *  // second argument is a list of options
+ *  const data = exporter.parse( mesh, { binary: true } );
+ *
+ */
+
+class STLExporter {
+  parse(scene, options = {}) {
+    options = Object.assign(
+      {
+        binary: false,
+      },
+      options,
+    )
+
+    const binary = options.binary
+
+    //
+
+    const objects = []
+    let triangles = 0
+
+    scene.traverse(function (object) {
+      if (object.isMesh) {
+        const geometry = object.geometry
+
+        const index = geometry.index
+        const positionAttribute = geometry.getAttribute('position')
+
+        triangles += index !== null ? index.count / 3 : positionAttribute.count / 3
+
+        objects.push({
+          object3d: object,
+          geometry: geometry,
+        })
+      }
+    })
+
+    let output
+    let offset = 80 // skip header
+
+    if (binary === true) {
+      const bufferLength = triangles * 2 + triangles * 3 * 4 * 4 + 80 + 4
+      const arrayBuffer = new ArrayBuffer(bufferLength)
+      output = new DataView(arrayBuffer)
+      output.setUint32(offset, triangles, true)
+      offset += 4
+    } else {
+      output = ''
+      output += 'solid exported\n'
+    }
+
+    const vA = new Vector3()
+    const vB = new Vector3()
+    const vC = new Vector3()
+    const cb = new Vector3()
+    const ab = new Vector3()
+    const normal = new Vector3()
+
+    for (let i = 0, il = objects.length; i < il; i++) {
+      const object = objects[i].object3d
+      const geometry = objects[i].geometry
+
+      const index = geometry.index
+      const positionAttribute = geometry.getAttribute('position')
+
+      if (index !== null) {
+        // indexed geometry
+
+        for (let j = 0; j < index.count; j += 3) {
+          const a = index.getX(j + 0)
+          const b = index.getX(j + 1)
+          const c = index.getX(j + 2)
+
+          writeFace(a, b, c, positionAttribute, object)
+        }
+      } else {
+        // non-indexed geometry
+
+        for (let j = 0; j < positionAttribute.count; j += 3) {
+          const a = j + 0
+          const b = j + 1
+          const c = j + 2
+
+          writeFace(a, b, c, positionAttribute, object)
+        }
+      }
+    }
+
+    if (binary === false) {
+      output += 'endsolid exported\n'
+    }
+
+    return output
+
+    function writeFace(a, b, c, positionAttribute, object) {
+      vA.fromBufferAttribute(positionAttribute, a)
+      vB.fromBufferAttribute(positionAttribute, b)
+      vC.fromBufferAttribute(positionAttribute, c)
+
+      if (object.isSkinnedMesh === true) {
+        object.applyBoneTransform(a, vA)
+        object.applyBoneTransform(b, vB)
+        object.applyBoneTransform(c, vC)
+      }
+
+      vA.applyMatrix4(object.matrixWorld)
+      vB.applyMatrix4(object.matrixWorld)
+      vC.applyMatrix4(object.matrixWorld)
+
+      writeNormal(vA, vB, vC)
+
+      writeVertex(vA)
+      writeVertex(vB)
+      writeVertex(vC)
+
+      if (binary === true) {
+        output.setUint16(offset, 0, true)
+        offset += 2
+      } else {
+        output += '\t\tendloop\n'
+        output += '\tendfacet\n'
+      }
+    }
+
+    function writeNormal(vA, vB, vC) {
+      cb.subVectors(vC, vB)
+      ab.subVectors(vA, vB)
+      cb.cross(ab).normalize()
+
+      normal.copy(cb).normalize()
+
+      if (binary === true) {
+        output.setFloat32(offset, normal.x, true)
+        offset += 4
+        output.setFloat32(offset, normal.y, true)
+        offset += 4
+        output.setFloat32(offset, normal.z, true)
+        offset += 4
+      } else {
+        output += '\tfacet normal ' + normal.x + ' ' + normal.y + ' ' + normal.z + '\n'
+        output += '\t\touter loop\n'
+      }
+    }
+
+    function writeVertex(vertex) {
+      if (binary === true) {
+        output.setFloat32(offset, vertex.x, true)
+        offset += 4
+        output.setFloat32(offset, vertex.y, true)
+        offset += 4
+        output.setFloat32(offset, vertex.z, true)
+        offset += 4
+      } else {
+        output += '\t\t\tvertex ' + vertex.x + ' ' + vertex.y + ' ' + vertex.z + '\n'
+      }
+    }
+  }
+}
+
+export { STLExporter }