Ninja render geometry is now parsed correctly.

src/data_formats/parsing/area_geometry.ts

@@ -1,7 +1,7 @@
 import { Cursor } from "../cursor/Cursor";
 import { Vec3 } from "../vector";
-import { ANGLE_TO_RAD } from "./ninja";
-import { parse_xj_model, XjModel } from "./ninja/xj";
+import { ANGLE_TO_RAD, NjObject, parse_xj_object } from "./ninja";
+import { XjModel } from "./ninja/xj";
 import { parse_rel } from "./rel";
 
 export type RenderObject = {
@@ -12,7 +12,7 @@ export type RenderSection = {
     id: number;
     position: Vec3;
     rotation: Vec3;
-    models: XjModel[];
+    objects: NjObject<XjModel>[];
 };
 
 export type Vertex = {
@@ -53,7 +53,7 @@ export function parse_area_geometry(cursor: Cursor): RenderObject {
         // const animated_geometry_offset_count = cursor.u32();
         // Ignore animated_geometry_offset_count and the last 4 bytes.
 
-        const models = parse_geometry_table(
+        const objects = parse_geometry_table(
             cursor,
             simple_geometry_offset_table_offset,
             simple_geometry_offset_count
@@ -63,19 +63,20 @@ export function parse_area_geometry(cursor: Cursor): RenderObject {
             id: section_id,
             position: section_position,
             rotation: section_rotation,
-            models,
+            objects,
         });
     }
 
     return { sections };
 }
 
+// TODO: don't reparse the same objects multiple times. Create DAG instead of tree.
 function parse_geometry_table(
     cursor: Cursor,
     table_offset: number,
     table_entry_count: number
-): XjModel[] {
-    const models: XjModel[] = [];
+): NjObject<XjModel>[] {
+    const objects: NjObject<XjModel>[] = [];
 
     for (let i = 0; i < table_entry_count; i++) {
         cursor.seek_start(table_offset + 16 * i);
@@ -88,14 +89,9 @@ function parse_geometry_table(
             offset = cursor.seek_start(offset).u32();
         }
 
-        cursor.seek_start(offset + 4);
-        const geometry_offset = cursor.u32();
-
-        if (geometry_offset > 0) {
-            cursor.seek_start(geometry_offset);
-            models.push(parse_xj_model(cursor));
-        }
+        cursor.seek_start(offset);
+        objects.push(...parse_xj_object(cursor));
     }
 
-    return models;
+    return objects;
 }

src/data_formats/parsing/ninja/index.ts

@@ -101,14 +101,27 @@ export type NjEvaluationFlags = {
     shape_skip: boolean;
 };
 
+/**
+ * Parses an NJCM file.
+ */
 export function parse_nj(cursor: Cursor): NjObject<NjcmModel>[] {
     return parse_ninja(cursor, parse_njcm_model, []);
 }
 
+/**
+ * Parses an NJCM file.
+ */
 export function parse_xj(cursor: Cursor): NjObject<XjModel>[] {
     return parse_ninja(cursor, parse_xj_model, undefined);
 }
 
+/**
+ * Parses a ninja object.
+ */
+export function parse_xj_object(cursor: Cursor): NjObject<XjModel>[] {
+    return parse_sibling_objects(cursor, parse_xj_model, undefined);
+}
+
 function parse_ninja<M extends NjModel>(
     cursor: Cursor,
     parse_model: (cursor: Cursor, context: any) => M,

src/rendering/conversion/GeometryBuilder.ts

@@ -0,0 +1,115 @@
+import { BufferGeometry, Float32BufferAttribute, Uint16BufferAttribute, Vector3 } from "three";
+
+export type BuilderVec2 = {
+    x: number;
+    y: number;
+};
+
+export type BuilderVec3 = {
+    x: number;
+    y: number;
+    z: number;
+};
+
+type VertexGroup = {
+    offset: number;
+    size: number;
+    material_index: number;
+};
+
+export class GeometryBuilder {
+    private positions: number[] = [];
+    private normals: number[] = [];
+    private uvs: number[] = [];
+    private indices: number[] = [];
+    private bone_indices: number[] = [];
+    private bone_weights: number[] = [];
+    private groups: VertexGroup[] = [];
+    private _max_material_index?: number;
+
+    get vertex_count(): number {
+        return this.positions.length / 3;
+    }
+
+    get index_count(): number {
+        return this.indices.length;
+    }
+
+    get max_material_index(): number | undefined {
+        return this._max_material_index;
+    }
+
+    get_position(index: number): Vector3 {
+        return new Vector3(
+            this.positions[3 * index],
+            this.positions[3 * index + 1],
+            this.positions[3 * index + 2]
+        );
+    }
+
+    get_normal(index: number): Vector3 {
+        return new Vector3(
+            this.normals[3 * index],
+            this.normals[3 * index + 1],
+            this.normals[3 * index + 2]
+        );
+    }
+
+    add_vertex(position: BuilderVec3, normal: BuilderVec3, uv: BuilderVec2): void {
+        this.positions.push(position.x, position.y, position.z);
+        this.normals.push(normal.x, normal.y, normal.z);
+        this.uvs.push(uv.x, uv.y);
+    }
+
+    add_index(index: number): void {
+        this.indices.push(index);
+    }
+
+    add_bone(index: number, weight: number): void {
+        this.bone_indices.push(index);
+        this.bone_weights.push(weight);
+    }
+
+    add_group(offset: number, size: number, material_id?: number): void {
+        const last_group = this.groups[this.groups.length - 1];
+        const mat_idx = material_id == null ? 0 : material_id + 1;
+
+        if (last_group && last_group.material_index === mat_idx) {
+            last_group.size += size;
+        } else {
+            this.groups.push({
+                offset,
+                size,
+                material_index: mat_idx,
+            });
+
+            this._max_material_index = this._max_material_index
+                ? Math.max(this._max_material_index, mat_idx)
+                : mat_idx;
+        }
+    }
+
+    build(): BufferGeometry {
+        const geom = new BufferGeometry();
+
+        geom.addAttribute("position", new Float32BufferAttribute(this.positions, 3));
+        geom.addAttribute("normal", new Float32BufferAttribute(this.normals, 3));
+        geom.addAttribute("uv", new Float32BufferAttribute(this.uvs, 2));
+
+        geom.setIndex(new Uint16BufferAttribute(this.indices, 1));
+
+        for (const group of this.groups) {
+            geom.addGroup(group.offset, group.size, group.material_index);
+        }
+
+        if (this.bone_indices.length) {
+            geom.addAttribute("skinIndex", new Uint16BufferAttribute(this.bone_indices, 4));
+            geom.addAttribute("skinWeight", new Float32BufferAttribute(this.bone_weights, 4));
+        }
+
+        geom.computeBoundingSphere();
+        geom.computeBoundingBox();
+
+        return geom;
+    }
+}

src/rendering/conversion/areas.ts

@@ -1,22 +1,19 @@
 import {
-    BufferGeometry,
     DoubleSide,
     Face3,
-    Float32BufferAttribute,
     Geometry,
     Group,
-    Matrix4,
     Mesh,
     MeshBasicMaterial,
     MeshLambertMaterial,
     Object3D,
-    Uint16BufferAttribute,
     Vector3,
 } from "three";
 import { CollisionObject } from "../../data_formats/parsing/area_collision_geometry";
 import { RenderObject } from "../../data_formats/parsing/area_geometry";
 import { Section } from "../../domain";
-import { xj_model_to_geometry } from "./xj_models";
+import { ninja_object_to_mesh, ninja_object_to_geometry_builder } from "./ninja_geometry";
+import { GeometryBuilder } from "./GeometryBuilder";
 
 const materials = [
     // Wall
@@ -120,21 +117,17 @@ export function area_geometry_to_sections_and_object_3d(
     const group = new Group();
 
     for (const section of object.sections) {
-        const positions: number[] = [];
-        const normals: number[] = [];
-        const indices: number[] = [];
+        const sec = new Section(section.id, section.position, section.rotation.y);
+        sections.push(sec);
 
-        for (const model of section.models) {
-            xj_model_to_geometry(model, new Matrix4(), positions, normals, [], indices, []);
+        const builder = new GeometryBuilder();
+
+        for (const object of section.objects) {
+            ninja_object_to_geometry_builder(object, builder);
         }
 
-        const geometry = new BufferGeometry();
-        geometry.addAttribute("position", new Float32BufferAttribute(positions, 3));
-        geometry.addAttribute("normal", new Float32BufferAttribute(normals, 3));
-        geometry.setIndex(new Uint16BufferAttribute(indices, 1));
-
         const mesh = new Mesh(
-            geometry,
+            builder.build(),
             new MeshLambertMaterial({
                 color: 0x44aaff,
                 transparent: true,
@@ -142,13 +135,9 @@ export function area_geometry_to_sections_and_object_3d(
                 side: DoubleSide,
             })
         );
-        mesh.position.set(section.position.x, section.position.y, section.position.z);
-        mesh.rotation.set(section.rotation.x, section.rotation.y, section.rotation.z);
-        group.add(mesh);
 
-        const sec = new Section(section.id, section.position, section.rotation.y);
         (mesh.userData as AreaUserData).section = sec;
-        sections.push(sec);
+        group.add(mesh);
     }
 
     return [sections, group];

src/rendering/conversion/ninja_geometry.ts

@@ -3,23 +3,23 @@ import {
     BufferGeometry,
     DoubleSide,
     Euler,
-    Float32BufferAttribute,
     Material,
     Matrix3,
     Matrix4,
+    Mesh,
+    MeshBasicMaterial,
     MeshLambertMaterial,
     Quaternion,
     Skeleton,
     SkinnedMesh,
-    Uint16BufferAttribute,
+    Vector2,
     Vector3,
-    MeshBasicMaterial,
-    Mesh,
 } from "three";
 import { vec3_to_threejs } from ".";
 import { is_njcm_model, NjModel, NjObject } from "../../data_formats/parsing/ninja";
 import { NjcmModel } from "../../data_formats/parsing/ninja/njcm";
-import { xj_model_to_geometry } from "./xj_models";
+import { XjModel } from "../../data_formats/parsing/ninja/xj";
+import { GeometryBuilder } from "./GeometryBuilder";
 
 const DUMMY_MATERIAL = new MeshBasicMaterial({
     color: 0x00ff00,
@@ -35,34 +35,42 @@ const DEFAULT_SKINNED_MATERIAL = new MeshLambertMaterial({
     side: DoubleSide,
 });
 const DEFAULT_NORMAL = new Vector3(0, 1, 0);
+const DEFAULT_UV = new Vector2(0, 0);
 const NO_TRANSLATION = new Vector3(0, 0, 0);
 const NO_ROTATION = new Quaternion(0, 0, 0, 1);
 const NO_SCALE = new Vector3(1, 1, 1);
 
-export function ninja_object_to_buffer_geometry(object: NjObject<NjModel>): BufferGeometry {
-    return new Object3DCreator([]).create_buffer_geometry(object);
+export function ninja_object_to_geometry_builder(
+    object: NjObject<NjModel>,
+    builder: GeometryBuilder
+) {
+    new ModelCreator(builder).to_geometry_builder(object);
 }
 
-export function ninja_object_to_mesh(object: NjObject<NjModel>, materials: Material[] = []): Mesh {
-    return new Object3DCreator(materials).create_mesh(object);
+export function ninja_object_to_buffer_geometry(object: NjObject<NjModel>): BufferGeometry {
+    return new ModelCreator(new GeometryBuilder()).create_buffer_geometry(object);
+}
+
+export function ninja_object_to_mesh(
+    object: NjObject<NjModel>,
+    materials: Material[] = [],
+    default_material: Material = DEFAULT_MATERIAL
+): Mesh {
+    return new ModelCreator(new GeometryBuilder()).create_mesh(object, materials, default_material);
 }
 
 export function ninja_object_to_skinned_mesh(
     object: NjObject<NjModel>,
-    materials: Material[] = []
+    materials: Material[] = [],
+    default_material: Material = DEFAULT_SKINNED_MATERIAL
 ): SkinnedMesh {
-    return new Object3DCreator(materials).create_skinned_mesh(object);
+    return new ModelCreator(new GeometryBuilder()).create_skinned_mesh(
+        object,
+        materials,
+        default_material
+    );
 }
 
-export type VertexGroup = {
-    /**
-     * Start index.
-     */
-    start: number;
-    count: number;
-    material_index: number;
-};
-
 type Vertex = {
     bone_id: number;
     position: Vector3;
@@ -94,70 +102,57 @@ class VerticesHolder {
     }
 }
 
-class Object3DCreator {
-    private materials: Material[];
+class ModelCreator {
     private vertices = new VerticesHolder();
     private bone_id: number = 0;
     private bones: Bone[] = [];
+    private builder: GeometryBuilder;
 
-    private positions: number[] = [];
-    private normals: number[] = [];
-    private uvs: number[] = [];
-    private indices: number[] = [];
-    private bone_indices: number[] = [];
-    private bone_weights: number[] = [];
-    private groups: VertexGroup[] = [];
+    constructor(builder: GeometryBuilder) {
+        this.builder = builder;
+    }
 
-    constructor(materials: Material[]) {
-        this.materials = [DUMMY_MATERIAL, ...materials];
+    to_geometry_builder(object: NjObject<NjModel>) {
+        this.object_to_geometry(object, undefined, new Matrix4());
     }
 
     create_buffer_geometry(object: NjObject<NjModel>): BufferGeometry {
-        this.object_to_geometry(object, undefined, new Matrix4());
-
-        const geom = new BufferGeometry();
-
-        geom.addAttribute("position", new Float32BufferAttribute(this.positions, 3));
-        geom.addAttribute("normal", new Float32BufferAttribute(this.normals, 3));
-        geom.addAttribute("uv", new Float32BufferAttribute(this.uvs, 2));
-
-        geom.setIndex(new Uint16BufferAttribute(this.indices, 1));
-
-        for (const group of this.groups) {
-            geom.addGroup(group.start, group.count, group.material_index);
-        }
-
-        geom.computeBoundingSphere();
-        geom.computeBoundingBox();
-
-        return geom;
+        this.to_geometry_builder(object);
+        return this.builder.build();
     }
 
-    create_mesh(object: NjObject<NjModel>): Mesh {
+    create_mesh(
+        object: NjObject<NjModel>,
+        materials: Material[],
+        default_material: Material
+    ): Mesh {
         const geom = this.create_buffer_geometry(object);
 
-        const max_mat_idx = this.groups.reduce((max, g) => Math.max(max, g.material_index), 0);
+        materials = [DUMMY_MATERIAL, ...materials];
+        const max_mat_idx = this.builder.max_material_index || 0;
 
-        for (let i = this.materials.length - 1; i < max_mat_idx; ++i) {
-            this.materials.push(DEFAULT_MATERIAL);
+        for (let i = materials.length - 1; i < max_mat_idx; ++i) {
+            materials.push(default_material);
         }
 
-        return new Mesh(geom, this.materials);
+        return new Mesh(geom, materials);
     }
 
-    create_skinned_mesh(object: NjObject<NjModel>): SkinnedMesh {
+    create_skinned_mesh(
+        object: NjObject<NjModel>,
+        materials: Material[],
+        default_material: Material
+    ): SkinnedMesh {
         const geom = this.create_buffer_geometry(object);
 
-        geom.addAttribute("skinIndex", new Uint16BufferAttribute(this.bone_indices, 4));
-        geom.addAttribute("skinWeight", new Float32BufferAttribute(this.bone_weights, 4));
+        materials = [DUMMY_MATERIAL, ...materials];
+        const max_mat_idx = this.builder.max_material_index || 0;
 
-        const max_mat_idx = this.groups.reduce((max, g) => Math.max(max, g.material_index), 0);
-
-        for (let i = this.materials.length - 1; i < max_mat_idx; ++i) {
-            this.materials.push(DEFAULT_SKINNED_MATERIAL);
+        for (let i = materials.length - 1; i < max_mat_idx; ++i) {
+            materials.push(default_material);
         }
 
-        const mesh = new SkinnedMesh(geom, this.materials);
+        const mesh = new SkinnedMesh(geom, materials);
         mesh.add(this.bones[0]);
         mesh.bind(new Skeleton(this.bones));
 
@@ -230,15 +225,7 @@ class Object3DCreator {
         if (is_njcm_model(model)) {
             this.njcm_model_to_geometry(model, matrix);
         } else {
-            xj_model_to_geometry(
-                model,
-                matrix,
-                this.positions,
-                this.normals,
-                this.uvs,
-                this.indices,
-                this.groups
-            );
+            this.xj_model_to_geometry(model, matrix);
         }
     }
 
@@ -247,7 +234,7 @@ class Object3DCreator {
 
         const new_vertices = model.vertices.map(vertex => {
             const position = vec3_to_threejs(vertex.position);
-            const normal = vertex.normal ? vec3_to_threejs(vertex.normal) : DEFAULT_NORMAL;
+            const normal = vertex.normal ? vec3_to_threejs(vertex.normal) : new Vector3(0, 1, 0);
 
             position.applyMatrix4(matrix);
             normal.applyMatrix3(normal_matrix);
@@ -265,7 +252,7 @@ class Object3DCreator {
         this.vertices.put(new_vertices);
 
         for (const mesh of model.meshes) {
-            const start_index_count = this.indices.length;
+            const start_index_count = this.builder.index_count;
 
             for (let i = 0; i < mesh.vertices.length; ++i) {
                 const mesh_vertex = mesh.vertices[i];
@@ -274,55 +261,121 @@ class Object3DCreator {
                 if (vertices.length) {
                     const vertex = vertices[0];
                     const normal = vertex.normal || mesh_vertex.normal || DEFAULT_NORMAL;
-                    const index = this.positions.length / 3;
+                    const index = this.builder.vertex_count;
 
-                    this.positions.push(vertex.position.x, vertex.position.y, vertex.position.z);
-                    this.normals.push(normal.x, normal.y, normal.z);
-
-                    if (mesh.has_tex_coords) {
-                        this.uvs.push(mesh_vertex.tex_coords!.x, mesh_vertex.tex_coords!.y);
-                    } else {
-                        this.uvs.push(0, 0);
-                    }
+                    this.builder.add_vertex(
+                        vertex.position,
+                        normal,
+                        mesh.has_tex_coords ? mesh_vertex.tex_coords! : DEFAULT_UV
+                    );
 
                     if (i >= 2) {
                         if (i % 2 === (mesh.clockwise_winding ? 1 : 0)) {
-                            this.indices.push(index - 2);
-                            this.indices.push(index - 1);
-                            this.indices.push(index);
+                            this.builder.add_index(index - 2);
+                            this.builder.add_index(index - 1);
+                            this.builder.add_index(index);
                         } else {
-                            this.indices.push(index - 2);
-                            this.indices.push(index);
-                            this.indices.push(index - 1);
+                            this.builder.add_index(index - 2);
+                            this.builder.add_index(index);
+                            this.builder.add_index(index - 1);
                         }
                     }
 
-                    const bone_indices = [0, 0, 0, 0];
-                    const bone_weights = [0, 0, 0, 0];
+                    const bones = [[0, 0], [0, 0], [0, 0], [0, 0]];
 
                     for (let j = vertices.length - 1; j >= 0; j--) {
                         const vertex = vertices[j];
-                        bone_indices[vertex.bone_weight_status] = vertex.bone_id;
-                        bone_weights[vertex.bone_weight_status] = vertex.bone_weight;
+                        bones[vertex.bone_weight_status] = [vertex.bone_id, vertex.bone_weight];
                     }
 
-                    this.bone_indices.push(...bone_indices);
-                    this.bone_weights.push(...bone_weights);
+                    for (const [bone_index, bone_weight] of bones) {
+                        this.builder.add_bone(bone_index, bone_weight);
+                    }
                 }
             }
 
-            const last_group = this.groups[this.groups.length - 1];
-            const mat_idx = mesh.texture_id == null ? 0 : mesh.texture_id + 1;
+            this.builder.add_group(
+                start_index_count,
+                this.builder.index_count - start_index_count,
+                mesh.texture_id
+            );
+        }
+    }
 
-            if (last_group && last_group.material_index === mat_idx) {
-                last_group.count += this.indices.length - start_index_count;
-            } else {
-                this.groups.push({
-                    start: start_index_count,
-                    count: this.indices.length - start_index_count,
-                    material_index: mat_idx,
-                });
+    private xj_model_to_geometry(model: XjModel, matrix: Matrix4): void {
+        const index_offset = this.builder.vertex_count;
+        const normal_matrix = new Matrix3().getNormalMatrix(matrix);
+
+        for (let { position, normal, uv } of model.vertices) {
+            const p = vec3_to_threejs(position).applyMatrix4(matrix);
+
+            const local_n = normal ? vec3_to_threejs(normal) : new Vector3(0, 1, 0);
+            const n = local_n.applyMatrix3(normal_matrix);
+
+            const tuv = uv || DEFAULT_UV;
+
+            this.builder.add_vertex(p, n, tuv);
+        }
+
+        let current_mat_idx: number | undefined;
+
+        for (const mesh of model.meshes) {
+            const start_index_count = this.builder.index_count;
+            let clockwise = false;
+
+            for (let j = 2; j < mesh.indices.length; ++j) {
+                const a = index_offset + mesh.indices[j - 2];
+                const b = index_offset + mesh.indices[j - 1];
+                const c = index_offset + mesh.indices[j];
+                const pa = this.builder.get_position(a);
+                const pb = this.builder.get_position(b);
+                const pc = this.builder.get_position(c);
+                const na = this.builder.get_normal(a);
+                const nb = this.builder.get_normal(b);
+                const nc = this.builder.get_normal(c);
+
+                // Calculate a surface normal and reverse the vertex winding if at least 2 of the vertex normals point in the opposite direction.
+                // This hack fixes the winding for most models.
+                const normal = pb
+                    .clone()
+                    .sub(pa)
+                    .cross(pc.clone().sub(pa));
+
+                if (clockwise) {
+                    normal.negate();
+                }
+
+                const opposite_count =
+                    (normal.dot(na) < 0 ? 1 : 0) +
+                    (normal.dot(nb) < 0 ? 1 : 0) +
+                    (normal.dot(nc) < 0 ? 1 : 0);
+
+                if (opposite_count >= 2) {
+                    clockwise = !clockwise;
+                }
+
+                if (clockwise) {
+                    this.builder.add_index(b);
+                    this.builder.add_index(a);
+                    this.builder.add_index(c);
+                } else {
+                    this.builder.add_index(a);
+                    this.builder.add_index(b);
+                    this.builder.add_index(c);
+                }
+
+                clockwise = !clockwise;
             }
+
+            if (mesh.material_properties.texture_id != null) {
+                current_mat_idx = mesh.material_properties.texture_id;
+            }
+
+            this.builder.add_group(
+                start_index_count,
+                this.builder.index_count - start_index_count,
+                current_mat_idx
+            );
         }
     }
 }

src/rendering/conversion/xj_models.ts

@@ -1,100 +0,0 @@
-import { Matrix3, Matrix4, Vector3 } from "three";
-import { vec3_to_threejs } from ".";
-import { XjModel } from "../../data_formats/parsing/ninja/xj";
-import { Vec2 } from "../../data_formats/vector";
-import { VertexGroup } from "./ninja_geometry";
-
-const DEFAULT_NORMAL = new Vector3(0, 1, 0);
-const DEFAULT_UV = new Vec2(0, 0);
-
-export function xj_model_to_geometry(
-    model: XjModel,
-    matrix: Matrix4,
-    positions: number[],
-    normals: number[],
-    uvs: number[],
-    indices: number[],
-    groups: VertexGroup[]
-): void {
-    const index_offset = positions.length / 3;
-    const normal_matrix = new Matrix3().getNormalMatrix(matrix);
-
-    for (let { position, normal, uv } of model.vertices) {
-        const p = vec3_to_threejs(position).applyMatrix4(matrix);
-        positions.push(p.x, p.y, p.z);
-
-        const local_n = normal ? vec3_to_threejs(normal) : DEFAULT_NORMAL;
-        const n = local_n.applyMatrix3(normal_matrix);
-        normals.push(n.x, n.y, n.z);
-
-        const tuv = uv || DEFAULT_UV;
-        uvs.push(tuv.x, tuv.y);
-    }
-
-    let current_mat_idx = 0;
-
-    for (const mesh of model.meshes) {
-        const start_index_count = indices.length;
-        let clockwise = true;
-
-        for (let j = 2; j < mesh.indices.length; ++j) {
-            const a = index_offset + mesh.indices[j - 2];
-            const b = index_offset + mesh.indices[j - 1];
-            const c = index_offset + mesh.indices[j];
-            const pa = new Vector3(positions[3 * a], positions[3 * a + 1], positions[3 * a + 2]);
-            const pb = new Vector3(positions[3 * b], positions[3 * b + 1], positions[3 * b + 2]);
-            const pc = new Vector3(positions[3 * c], positions[3 * c + 1], positions[3 * c + 2]);
-            const na = new Vector3(normals[3 * a], normals[3 * a + 1], normals[3 * a + 2]);
-            const nb = new Vector3(normals[3 * a], normals[3 * a + 1], normals[3 * a + 2]);
-            const nc = new Vector3(normals[3 * a], normals[3 * a + 1], normals[3 * a + 2]);
-
-            // Calculate a surface normal and reverse the vertex winding if at least 2 of the vertex normals point in the opposite direction.
-            // This hack fixes the winding for most models.
-            const normal = pb
-                .clone()
-                .sub(pa)
-                .cross(pc.clone().sub(pa));
-
-            if (clockwise) {
-                normal.negate();
-            }
-
-            const opposite_count =
-                (normal.dot(na) < 0 ? 1 : 0) +
-                (normal.dot(nb) < 0 ? 1 : 0) +
-                (normal.dot(nc) < 0 ? 1 : 0);
-
-            if (opposite_count >= 2) {
-                clockwise = !clockwise;
-            }
-
-            if (clockwise) {
-                indices.push(b);
-                indices.push(a);
-                indices.push(c);
-            } else {
-                indices.push(a);
-                indices.push(b);
-                indices.push(c);
-            }
-
-            clockwise = !clockwise;
-        }
-
-        const last_group = groups[groups.length - 1];
-
-        if (mesh.material_properties.texture_id != null) {
-            current_mat_idx = mesh.material_properties.texture_id + 1;
-        }
-
-        if (last_group && last_group.material_index === current_mat_idx) {
-            last_group.count += indices.length - start_index_count;
-        } else {
-            groups.push({
-                start: start_index_count,
-                count: indices.length - start_index_count,
-                material_index: current_mat_idx,
-            });
-        }
-    }
-}