landing

gacha/OBJFile.js

@@ -0,0 +1,210 @@
+class OBJFile {
+  constructor(fileContents, defaultModelName) {
+    this._reset();
+    this.fileContents = fileContents;
+    this.defaultModelName = (defaultModelName || 'untitled');
+  }
+
+  _reset() {
+    this.result = {
+      models: [],
+      materialLibraries: []
+    };
+    this.currentMaterial = '';
+    this.currentGroup = '';
+    this.smoothingGroup = 0;
+  }
+
+  parse() {
+    this._reset();
+
+    const _stripComments = (lineString) => {
+      const commentIndex = lineString.indexOf('#');
+      if (commentIndex > -1) { return lineString.substring(0, commentIndex); }
+      return lineString;
+    };
+
+    const lines = this.fileContents.split('\n');
+    for (let i = 0; i < lines.length; i += 1) {
+      const line = _stripComments(lines[i]);
+
+      const lineItems = line.replace(/\s+/g, ' ').trim().split(' ');
+
+      switch (lineItems[0].toLowerCase()) {
+        case 'o': // Start A New Model
+          this._parseObject(lineItems);
+          break;
+        case 'g': // Start a new polygon group
+          this._parseGroup(lineItems);
+          break;
+        case 'v': // Define a vertex for the current model
+          this._parseVertexCoords(lineItems);
+          break;
+        case 'vt': // Texture Coords
+          this._parseTextureCoords(lineItems);
+          break;
+        case 'vn': // Define a vertex normal for the current model
+          this._parseVertexNormal(lineItems);
+          break;
+        case 'l': // Define a line for the current model
+          this._parseLine(lineItems);
+          break;
+        case 's': // Smooth shading statement
+          this._parseSmoothShadingStatement(lineItems);
+          break;
+        case 'f': // Define a Face/Polygon
+          this._parsePolygon(lineItems);
+          break;
+        case 'mtllib': // Reference to a material library file (.mtl)
+          this._parseMtlLib(lineItems);
+          break;
+        case 'usemtl': // Sets the current material to be applied to polygons defined from this point forward
+          this._parseUseMtl(lineItems);
+          break;
+      }
+    }
+
+    return this.result;
+  }
+
+  _createNewModel(name = this.defaultModelName) {
+    return {
+      name,
+      vertices: [],
+      textureCoords: [],
+      vertexNormals: [],
+      faces: [],
+      lines: []
+    };
+  }
+
+  _currentModel() {
+    if (this.result.models.length == 0) {
+      const defaultModel = this._createNewModel();
+      this.result.models.push(defaultModel);
+      this.currentGroup = '';
+      this.smoothingGroup = 0;
+    }
+
+    return this.result.models[this.result.models.length - 1];
+  }
+
+  _parseObject(lineItems) {
+    const modelName = lineItems.length >= 2 ? lineItems[1] : this.defaultModelName;
+    const model = this._createNewModel(modelName);
+    this.result.models.push(model);
+    this.currentGroup = '';
+    this.smoothingGroup = 0;
+  }
+
+  _parseGroup(lineItems) {
+    if (lineItems.length != 2) { throw 'Group statements must have exactly 1 argument (eg. g group_1)'; }
+
+    this.currentGroup = lineItems[1];
+  }
+
+  _parseVertexCoords(lineItems) {
+    const x = lineItems.length >= 2 ? parseFloat(lineItems[1]) : 0.0;
+    const y = lineItems.length >= 3 ? parseFloat(lineItems[2]) : 0.0;
+    const z = lineItems.length >= 4 ? parseFloat(lineItems[3]) : 0.0;
+
+    this._currentModel().vertices.push({ x, y, z });
+  }
+
+  _parseTextureCoords(lineItems) {
+    const u = lineItems.length >= 2 ? parseFloat(lineItems[1]) : 0.0;
+    const v = lineItems.length >= 3 ? parseFloat(lineItems[2]) : 0.0;
+    const w = lineItems.length >= 4 ? parseFloat(lineItems[3]) : 0.0;
+
+    this._currentModel().textureCoords.push({ u, v, w });
+  }
+
+  _parseVertexNormal(lineItems) {
+    const x = lineItems.length >= 2 ? parseFloat(lineItems[1]) : 0.0;
+    const y = lineItems.length >= 3 ? parseFloat(lineItems[2]) : 0.0;
+    const z = lineItems.length >= 4 ? parseFloat(lineItems[3]) : 0.0;
+
+    this._currentModel().vertexNormals.push({ x, y, z });
+  }
+
+  _parseLine(lineItems) {
+    const totalVertices = (lineItems.length - 1);
+    if (totalVertices < 2) { throw (`Line statement has less than 2 vertices${this.filePath}${this.lineNumber}`); }
+
+    const line = [];
+
+    for (let i = 0; i < totalVertices; i += 1) {
+      const vertexString = lineItems[i + 1];
+      const vertexValues = vertexString.split('/');
+
+      if (vertexValues.length < 1 || vertexValues.length > 2) { throw (`Too many values (separated by /) for a single vertex${this.filePath}${this.lineNumber}`); }
+
+      let vertexIndex = 0;
+      let textureCoordsIndex = 0;
+      vertexIndex = parseInt(vertexValues[0]);
+      if (vertexValues.length > 1 && (vertexValues[1] != '')) { textureCoordsIndex = parseInt(vertexValues[1]); }
+
+      line.push({
+        vertexIndex,
+        textureCoordsIndex
+      });
+    }
+    this._currentModel().lines.push(line);
+  }
+
+  _parsePolygon(lineItems) {
+    const totalVertices = (lineItems.length - 1);
+    if (totalVertices < 3) { throw (`Face statement has less than 3 vertices${this.filePath}${this.lineNumber}`); }
+
+    const face = {
+      material: this.currentMaterial,
+      group: this.currentGroup,
+      smoothingGroup: this.smoothingGroup,
+      vertices: []
+    };
+
+    for (let i = 0; i < totalVertices; i += 1) {
+      const vertexString = lineItems[i + 1];
+      const vertexValues = vertexString.split('/');
+
+      if (vertexValues.length < 1 || vertexValues.length > 3) { throw (`Too many values (separated by /) for a single vertex${this.filePath}${this.lineNumber}`); }
+
+      let vertexIndex = 0;
+      let textureCoordsIndex = 0;
+      let vertexNormalIndex = 0;
+      vertexIndex = parseInt(vertexValues[0]);
+      if (vertexValues.length > 1 && (vertexValues[1] != '')) { textureCoordsIndex = parseInt(vertexValues[1]); }
+      if (vertexValues.length > 2) { vertexNormalIndex = parseInt(vertexValues[2]); }
+
+      if (vertexIndex == 0) { throw 'Faces uses invalid vertex index of 0'; }
+
+      // Negative vertex indices refer to the nth last defined vertex
+      // convert these to postive indices for simplicity
+      if (vertexIndex < 0) { vertexIndex = this._currentModel().vertices.length + 1 + vertexIndex; }
+
+      face.vertices.push({
+        vertexIndex,
+        textureCoordsIndex,
+        vertexNormalIndex
+      });
+    }
+    this._currentModel().faces.push(face);
+  }
+
+  _parseMtlLib(lineItems) {
+    if (lineItems.length >= 2) { this.result.materialLibraries.push(lineItems[1]); }
+  }
+
+  _parseUseMtl(lineItems) {
+    if (lineItems.length >= 2) { this.currentMaterial = lineItems[1]; }
+  }
+
+  _parseSmoothShadingStatement(lineItems) {
+    if (lineItems.length != 2) { throw 'Smoothing group statements must have exactly 1 argument (eg. s <number|off>)'; }
+
+    const groupNumber = (lineItems[1].toLowerCase() == 'off') ? 0 : parseInt(lineItems[1]);
+    this.smoothingGroup = groupNumber;
+  }
+}
+
+export { OBJFile }