Adds vertex prediction

src/Loader.js

@@ -98,6 +98,15 @@ function parseLine(line) {
             );
             return element;
 
+        case "pv":
+            element.type = Element.PredictVertex;
+            element.value = new THREE.Face3(
+                parseInt(split[2], 10) - 1,
+                parseInt(split[2], 10) - 1,
+                parseInt(split[2], 10) - 1,
+            );
+            return element;
+
         case "efv":
             element.type = Element.EditFaceVertex;
             element.id = parseInt(split[1], 10) - 1;
@@ -140,6 +149,7 @@ Element.EditFace = "EditFace";
 Element.EditFaceVertex = "EditFaceVertex";
 Element.TranslateVertex = "TranslateVertex";
 Element.DeleteFace = "DeleteFace";
+Element.PredictVertex = "PredictVertex";
 
 class Loader {
     constructor(path, chunkSize = 1024, timeout = 20) {

src/Model.js

@@ -47,6 +47,25 @@ class Model extends THREE.Mesh {
 
     }
 
+
+    checkVertexPrediction(f) {
+        let vertices = this.geometry.vertices;
+
+        if (vertices[f.a] === undefined) {
+            this.throwError("Vertex prediction requires vertex " + (f.a + 1) + " but there is no such vertex");
+        }
+
+        if (vertices[f.b] === undefined) {
+            this.throwError("Vertex prediction requires vertex " + (f.b + 1) + " but there is no such vertex");
+        }
+
+        if (vertices[f.c] === undefined) {
+            this.throwError("Vertex prediction requires vertex " + (f.c + 1) + " but there is no such vertex");
+        }
+
+    }
+
+
     manageElement(element) {
 
         let vertices = this.geometry.vertices;
@@ -142,6 +161,13 @@ class Model extends THREE.Mesh {
                 this.geometry.elementsNeedUpdate = true;
                 break;
 
+            case Element.PredictVertex:
+                this.checkVertexPrediction(element.value);
+                vertices.push(vertices[element.value.a].clone()
+                    .add(vertices[element.value.c])
+                    .sub(vertices[element.value.b]));
+                this.geometry.verticesNeedUpdate = true;
+                break;
 
             default:
                 throw new Error("unknown element type: " + element.type);