phantasmal-world/src/rendering/areas.ts

import {
    DoubleSide,
    Face3,
    Geometry,
    Group,
    Mesh,
    MeshBasicMaterial,
    MeshLambertMaterial,
    Object3D,
    Vector3,
} from "three";
import { CollisionObject } from "../data_formats/parsing/area_collision_geometry";

const materials = [
    // Wall
    new MeshBasicMaterial({
        color: 0x80c0d0,
        transparent: true,
        opacity: 0.25,
    }),
    // Ground
    new MeshLambertMaterial({
        color: 0x50d0d0,
        side: DoubleSide,
    }),
    // Vegetation
    new MeshLambertMaterial({
        color: 0x50b070,
        side: DoubleSide,
    }),
    // Section transition zone
    new MeshLambertMaterial({
        color: 0x604080,
        side: DoubleSide,
    }),
];
const wireframe_materials = [
    // Wall
    new MeshBasicMaterial({
        color: 0x90d0e0,
        wireframe: true,
        transparent: true,
        opacity: 0.3,
    }),
    // Ground
    new MeshBasicMaterial({
        color: 0x60f0f0,
        wireframe: true,
    }),
    // Vegetation
    new MeshBasicMaterial({
        color: 0x60c080,
        wireframe: true,
    }),
    // Section transition zone
    new MeshBasicMaterial({
        color: 0x705090,
        wireframe: true,
    }),
];

export function area_collision_geometry_to_object_3d(object: CollisionObject): Object3D {
    const group = new Group();

    for (const collision_mesh of object.meshes) {
        // Use Geometry and not BufferGeometry for better raycaster performance.
        const geom = new Geometry();

        for (const { x, y, z } of collision_mesh.vertices) {
            geom.vertices.push(new Vector3(x, y, z));
        }

        for (const { indices, flags, normal } of collision_mesh.triangles) {
            const is_section_transition = flags & 0b1000000;
            const is_vegetation = flags & 0b10000;
            const is_ground = flags & 0b1;
            const color_index = is_section_transition ? 3 : is_vegetation ? 2 : is_ground ? 1 : 0;

            geom.faces.push(
                new Face3(
                    indices[0],
                    indices[1],
                    indices[2],
                    new Vector3(normal.x, normal.y, normal.z),
                    undefined,
                    color_index
                )
            );
        }

        const mesh = new Mesh(geom, materials);
        mesh.renderOrder = 1;
        group.add(mesh);

        const wireframe_mesh = new Mesh(geom, wireframe_materials);
        wireframe_mesh.renderOrder = 2;
        group.add(wireframe_mesh);
    }

    return group;
}