Babylon.js/loaders/src/STL/stlFileLoader.ts

import { Nullable } from "babylonjs/types";
import { Tools } from "babylonjs/Misc/tools";
import { VertexBuffer } from "babylonjs/Meshes/buffer";
import { Skeleton } from "babylonjs/Bones/skeleton";
import { IParticleSystem } from "babylonjs/Particles/IParticleSystem";
import { AbstractMesh } from "babylonjs/Meshes/abstractMesh";
import { Mesh } from "babylonjs/Meshes/mesh";
import { SceneLoader, ISceneLoaderPlugin, ISceneLoaderPluginExtensions } from "babylonjs/Loading/sceneLoader";
import { AssetContainer } from "babylonjs/assetContainer";
import { Scene } from "babylonjs/scene";

/**
 * STL file type loader.
 * This is a babylon scene loader plugin.
 */
export class STLFileLoader implements ISceneLoaderPlugin {

    /** @hidden */
    public solidPattern = /solid (\S*)([\S\s]*?)endsolid[ ]*(\S*)/g;

    /** @hidden */
    public facetsPattern = /facet([\s\S]*?)endfacet/g;
    /** @hidden */
    public normalPattern = /normal[\s]+([\-+]?[0-9]+\.?[0-9]*([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+/g;
    /** @hidden */
    public vertexPattern = /vertex[\s]+([\-+]?[0-9]+\.?[0-9]*([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+[\s]+([\-+]?[0-9]*\.?[0-9]+([eE][\-+]?[0-9]+)?)+/g;

    /**
     * Defines the name of the plugin.
     */
    public name = "stl";

    /**
     * Defines the extensions the stl loader is able to load.
     * force data to come in as an ArrayBuffer
     * we'll convert to string if it looks like it's an ASCII .stl
     */
    public extensions: ISceneLoaderPluginExtensions = {
        ".stl": { isBinary: true },
    };

    /**
     * Import meshes into a scene.
     * @param meshesNames An array of mesh names, a single mesh name, or empty string for all meshes that filter what meshes are imported
     * @param scene The scene to import into
     * @param data The data to import
     * @param rootUrl The root url for scene and resources
     * @param meshes The meshes array to import into
     * @param particleSystems The particle systems array to import into
     * @param skeletons The skeletons array to import into
     * @param onError The callback when import fails
     * @returns True if successful or false otherwise
     */
    public importMesh(meshesNames: any, scene: Scene, data: any, rootUrl: string, meshes: Nullable<AbstractMesh[]>, particleSystems: Nullable<IParticleSystem[]>, skeletons: Nullable<Skeleton[]>): boolean {
        var matches;

        if (typeof data !== "string") {

            if (this._isBinary(data)) {
                // binary .stl
                var babylonMesh = new Mesh("stlmesh", scene);
                this._parseBinary(babylonMesh, data);
                if (meshes) {
                    meshes.push(babylonMesh);
                }
                return true;
            }

            // ASCII .stl

            // convert to string
            var array_buffer = new Uint8Array(data);
            var str = '';
            for (var i = 0; i < data.byteLength; i++) {
                str += String.fromCharCode(array_buffer[i]); // implicitly assumes little-endian
            }
            data = str;
        }

        //if arrived here, data is a string, containing the STLA data.

        while (matches = this.solidPattern.exec(data)) {
            var meshName = matches[1];
            var meshNameFromEnd = matches[3];
            if (meshName != meshNameFromEnd) {
                Tools.Error("Error in STL, solid name != endsolid name");
                return false;
            }

            // check meshesNames
            if (meshesNames && meshName) {
                if (meshesNames instanceof Array) {
                    if (!meshesNames.indexOf(meshName)) {
                        continue;
                    }
                } else {
                    if (meshName !== meshesNames) {
                        continue;
                    }
                }
            }

            // stl mesh name can be empty as well
            meshName = meshName || "stlmesh";

            var babylonMesh = new Mesh(meshName, scene);
            this._parseASCII(babylonMesh, matches[2]);
            if (meshes) {
                meshes.push(babylonMesh);
            }
        }

        return true;

    }

    /**
     * Load into a scene.
     * @param scene The scene to load into
     * @param data The data to import
     * @param rootUrl The root url for scene and resources
     * @param onError The callback when import fails
     * @returns true if successful or false otherwise
     */
    public load(scene: Scene, data: any, rootUrl: string): boolean {
        var result = this.importMesh(null, scene, data, rootUrl, null, null, null);
        return result;
    }

    /**
     * Load into an asset container.
     * @param scene The scene to load into
     * @param data The data to import
     * @param rootUrl The root url for scene and resources
     * @param onError The callback when import fails
     * @returns The loaded asset container
     */
    public loadAssetContainer(scene: Scene, data: string, rootUrl: string, onError?: (message: string, exception?: any) => void): AssetContainer {
        var container = new AssetContainer(scene);
        scene._blockEntityCollection = true;
        this.importMesh(null, scene, data, rootUrl, container.meshes, null, null);
        scene._blockEntityCollection = false;
        return container;
    }

    private _isBinary(data: any) {

        // check if file size is correct for binary stl
        var faceSize, nFaces, reader;
        reader = new DataView(data);
        faceSize = (32 / 8 * 3) + ((32 / 8 * 3) * 3) + (16 / 8);
        nFaces = reader.getUint32(80, true);

        if (80 + (32 / 8) + (nFaces * faceSize) === reader.byteLength) {
            return true;
        }

        // check characters higher than ASCII to confirm binary
        var fileLength = reader.byteLength;
        for (var index = 0; index < fileLength; index++) {
            if (reader.getUint8(index) > 127) {
                return true;
            }
        }

        return false;
    }

    private _parseBinary(mesh: Mesh, data: ArrayBuffer) {

        var reader = new DataView(data);
        var faces = reader.getUint32(80, true);

        var dataOffset = 84;
        var faceLength = 12 * 4 + 2;

        var offset = 0;

        var positions = new Float32Array(faces * 3 * 3);
        var normals = new Float32Array(faces * 3 * 3);
        var indices = new Uint32Array(faces * 3);
        var indicesCount = 0;

        for (var face = 0; face < faces; face++) {

            var start = dataOffset + face * faceLength;
            var normalX = reader.getFloat32(start, true);
            var normalY = reader.getFloat32(start + 4, true);
            var normalZ = reader.getFloat32(start + 8, true);

            for (var i = 1; i <= 3; i++) {

                var vertexstart = start + i * 12;

                // ordering is intentional to match ascii import
                positions[offset] = reader.getFloat32(vertexstart, true);
                positions[offset + 2] = reader.getFloat32(vertexstart + 4, true);
                positions[offset + 1] = reader.getFloat32(vertexstart + 8, true);

                normals[offset] = normalX;
                normals[offset + 2] = normalY;
                normals[offset + 1] = normalZ;

                offset += 3;
            }
            indices[indicesCount] = indicesCount++;
            indices[indicesCount] = indicesCount++;
            indices[indicesCount] = indicesCount++;
        }

        mesh.setVerticesData(VertexBuffer.PositionKind, positions);
        mesh.setVerticesData(VertexBuffer.NormalKind, normals);
        mesh.setIndices(indices);
        mesh.computeWorldMatrix(true);
    }

    private _parseASCII(mesh: Mesh, solidData: string) {

        var positions = [];
        var normals = [];
        var indices = [];
        var indicesCount = 0;

        //load facets, ignoring loop as the standard doesn't define it can contain more than vertices
        var matches;
        while (matches = this.facetsPattern.exec(solidData)) {
            var facet = matches[1];
            //one normal per face
            var normalMatches = this.normalPattern.exec(facet);
            this.normalPattern.lastIndex = 0;
            if (!normalMatches) {
                continue;
            }
            var normal = [Number(normalMatches[1]), Number(normalMatches[5]), Number(normalMatches[3])];

            var vertexMatch;
            while (vertexMatch = this.vertexPattern.exec(facet)) {
                positions.push(Number(vertexMatch[1]), Number(vertexMatch[5]), Number(vertexMatch[3]));
                normals.push(normal[0], normal[1], normal[2]);
            }
            indices.push(indicesCount++, indicesCount++, indicesCount++);
            this.vertexPattern.lastIndex = 0;
        }

        this.facetsPattern.lastIndex = 0;
        mesh.setVerticesData(VertexBuffer.PositionKind, positions);
        mesh.setVerticesData(VertexBuffer.NormalKind, normals);
        mesh.setIndices(indices);
        mesh.computeWorldMatrix(true);
    }
}

if (SceneLoader) {
    SceneLoader.RegisterPlugin(new STLFileLoader());
}