sevkin/loader.html

## loader.html
<!doctype html>
<html>
<head>
<meta charset="utf-8" />
<title>STL File Viewer</title>
<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r68/three.min.js"
></script>
<script src="https://rawgit.com/mrdoob/three.js/master/examples/js/controls/TrackballControls.js"
></script>
<script src="loader.js"></script>
<script src="stl.js"></script>
</head>
<body>
<div>
select stl file: <input type="file" id="file" /> or drop stl file
</div>
<div id="view"></div>
</body>
</html>

## loader.js
window.addEventListener("load", function () {
    "use strict";

    var w = 800, h = 800;

    var renderer = new THREE.WebGLRenderer();
    renderer.setSize(w, h);
    var view = document.getElementById("view");
    view.appendChild(renderer.domElement);

    var camera = new THREE.PerspectiveCamera(45, w / h, 1, 1000);
    camera.position.set(0, 0, 50);
    var controls = new THREE.TrackballControls(camera, view);

    var scene = new THREE.Scene();
    scene.add(new THREE.AmbientLight(0x666666));

    var light1 = new THREE.DirectionalLight(0xffffff);
    light1.position.set(0, 100, 100);
    scene.add(light1);

    var light2 = new THREE.DirectionalLight(0xffffff);
    light2.position.set(0, -100, -100);
    scene.add(light2);

    var mat = new THREE.MeshPhongMaterial({
        color: 0x339900, ambient: 0x339900, specular: 0x030303,
    });
    var obj = new THREE.Mesh(new THREE.Geometry(), mat);
    scene.add(obj);

    var loop = function loop() {
        requestAnimationFrame(loop);
        //obj.rotation.z += 0.05;
        controls.update();
        renderer.clear();
        renderer.render(scene, camera);
    };
    loop();

    // file load
    var openFile = function (file) {
        var reader = new FileReader();
        reader.addEventListener("load", function (ev) {
            var buffer = ev.target.result;
            var geom = loadStl(buffer);
            scene.remove(obj);
            obj = new THREE.Mesh(geom, mat);
            scene.add(obj);
        }, false);
        reader.readAsArrayBuffer(file);
    };

    // file input button
    var input = document.getElementById("file");
    input.addEventListener("change", function (ev) {
        var file = ev.target.files[0];
        openFile(file);
    }, false);

    // dnd
    view.addEventListener("dragover", function (ev) {
        ev.stopPropagation();
        ev.preventDefault();
        ev.dataTransfer.dropEffect = "copy";
    }, false);
    view.addEventListener("drop", function (ev) {
        ev.stopPropagation();
        ev.preventDefault();
        var file = ev.dataTransfer.files[0];
        openFile(file);
    }, false);
}, false);

## stl.js
var loadStl = (function () {
    var binaryVector3 = function (view, offset) {
        var v = new THREE.Vector3();
        v.x = view.getFloat32(offset + 0, true);
        v.y = view.getFloat32(offset + 4, true);
        v.z = view.getFloat32(offset + 8, true);
        return v;
    };

    var loadBinaryStl = function (buffer) {
        // binary STL
        var view = new DataView(buffer);
        var size = view.getUint32(80, true);
        var geom = new THREE.Geometry();
        var offset = 84;
        for (var i = 0; i < size; i++) {
            var normal = binaryVector3(view, offset);
            geom.vertices.push(binaryVector3(view, offset + 12));
            geom.vertices.push(binaryVector3(view, offset + 24));
            geom.vertices.push(binaryVector3(view, offset + 36));
            geom.faces.push(
                new THREE.Face3(i * 3, i * 3 + 1, i * 3 + 2, normal));
            offset += 4 * 3 * 4 + 2;
        }
        return geom;
    };


    var m2vec3 = function (match) {
        var v = new THREE.Vector3();
        v.x = parseFloat(match[1]);
        v.y = parseFloat(match[2]);
        v.z = parseFloat(match[3]);
        return v;
    };
    var toLines = function (array) {
        var lines = [];
        var h = 0;
        for (var i = 0; i < array.length; i++) {
            if (array[i] === 10) {
                var line = String.fromCharCode.apply(
                    null, array.subarray(h, i));
                lines.push(line);
                h = i + 1;
            }
        }
        lines.push(String.fromCharCode.apply(null, array.subarray(h)));
        return lines;
    }
    var loadTextStl = function (buffer) {
        var lines = toLines(new Uint8Array(buffer));
        var index = 0;
        var scan = function (regexp) {
            while (lines[index].match(/^\s*$/)) index++;
            var r = lines[index].match(regexp);
            return r;
        };
        var scanOk = function (regexp) {
            var r = scan(regexp);
            if (!r) throw new Error(
                "not text stl: " + regexp.toString() +
                "=> (line " + (index - 1) + ")" +
                "[" + lines[index-1] + "]");
            index++;
            return r;
        }

        var facetReg = /^\s*facet\s+normal\s+([^\s]+)\s+([^\s]+)\s+([^\s]+)/;
        var vertexReg = /^\s*vertex\s+([^s]+)\s+([^\s]+)\s+([^\s]+)/;
        var geom = new THREE.Geometry();
        scanOk(/^\s*solid\s(.*)/);
        while (!scan(/^\s*endsolid/)) {
            var normal = scanOk(facetReg);
            scanOk(/^\s*outer\s+loop/);
            var v1 = scanOk(vertexReg);
            var v2 = scanOk(vertexReg);
            var v3 = scanOk(vertexReg);
            scanOk(/\s*endloop/);
            scanOk(/\s*endfacet/);
            var base = geom.vertices.length;
            geom.vertices.push(m2vec3(v1));
            geom.vertices.push(m2vec3(v2));
            geom.vertices.push(m2vec3(v3));
            geom.faces.push(
                new THREE.Face3(base, base + 1, base + 2, m2vec3(normal)));
        }
        return geom;
    };

    return function (buffer) {
        try {
            console.log("load as text stl");
            return loadTextStl(buffer);
        } catch (ex) {
            console.log(ex);
            console.log("load as binary stl");
            return loadBinaryStl(buffer);
        }
    };
})();
	<!doctype html>
	<html>
	<head>
	<meta charset="utf-8" />
	<title>STL File Viewer</title>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r68/three.min.js"
	></script>
	<script src="https://rawgit.com/mrdoob/three.js/master/examples/js/controls/TrackballControls.js"
	></script>
	<script src="loader.js"></script>
	<script src="stl.js"></script>
	</head>
	<body>
	<div>
	select stl file: <input type="file" id="file" /> or drop stl file
	</div>
	<div id="view"></div>
	</body>
	</html>
	window.addEventListener("load", function () {
	"use strict";

	var w = 800, h = 800;

	var renderer = new THREE.WebGLRenderer();
	renderer.setSize(w, h);
	var view = document.getElementById("view");
	view.appendChild(renderer.domElement);

	var camera = new THREE.PerspectiveCamera(45, w / h, 1, 1000);
	camera.position.set(0, 0, 50);
	var controls = new THREE.TrackballControls(camera, view);

	var scene = new THREE.Scene();
	scene.add(new THREE.AmbientLight(0x666666));

	var light1 = new THREE.DirectionalLight(0xffffff);
	light1.position.set(0, 100, 100);
	scene.add(light1);

	var light2 = new THREE.DirectionalLight(0xffffff);
	light2.position.set(0, -100, -100);
	scene.add(light2);

	var mat = new THREE.MeshPhongMaterial({
	color: 0x339900, ambient: 0x339900, specular: 0x030303,
	});
	var obj = new THREE.Mesh(new THREE.Geometry(), mat);
	scene.add(obj);

	var loop = function loop() {
	requestAnimationFrame(loop);
	//obj.rotation.z += 0.05;
	controls.update();
	renderer.clear();
	renderer.render(scene, camera);
	};
	loop();

	// file load
	var openFile = function (file) {
	var reader = new FileReader();
	reader.addEventListener("load", function (ev) {
	var buffer = ev.target.result;
	var geom = loadStl(buffer);
	scene.remove(obj);
	obj = new THREE.Mesh(geom, mat);
	scene.add(obj);
	}, false);
	reader.readAsArrayBuffer(file);
	};

	// file input button
	var input = document.getElementById("file");
	input.addEventListener("change", function (ev) {
	var file = ev.target.files[0];
	openFile(file);
	}, false);

	// dnd
	view.addEventListener("dragover", function (ev) {
	ev.stopPropagation();
	ev.preventDefault();
	ev.dataTransfer.dropEffect = "copy";
	}, false);
	view.addEventListener("drop", function (ev) {
	ev.stopPropagation();
	ev.preventDefault();
	var file = ev.dataTransfer.files[0];
	openFile(file);
	}, false);
	}, false);
	var loadStl = (function () {
	var binaryVector3 = function (view, offset) {
	var v = new THREE.Vector3();
	v.x = view.getFloat32(offset + 0, true);
	v.y = view.getFloat32(offset + 4, true);
	v.z = view.getFloat32(offset + 8, true);
	return v;
	};

	var loadBinaryStl = function (buffer) {
	// binary STL
	var view = new DataView(buffer);
	var size = view.getUint32(80, true);
	var geom = new THREE.Geometry();
	var offset = 84;
	for (var i = 0; i < size; i++) {
	var normal = binaryVector3(view, offset);
	geom.vertices.push(binaryVector3(view, offset + 12));
	geom.vertices.push(binaryVector3(view, offset + 24));
	geom.vertices.push(binaryVector3(view, offset + 36));
	geom.faces.push(
	new THREE.Face3(i * 3, i * 3 + 1, i * 3 + 2, normal));
	offset += 4 * 3 * 4 + 2;
	}
	return geom;
	};


	var m2vec3 = function (match) {
	var v = new THREE.Vector3();
	v.x = parseFloat(match[1]);
	v.y = parseFloat(match[2]);
	v.z = parseFloat(match[3]);
	return v;
	};
	var toLines = function (array) {
	var lines = [];
	var h = 0;
	for (var i = 0; i < array.length; i++) {
	if (array[i] === 10) {
	var line = String.fromCharCode.apply(
	null, array.subarray(h, i));
	lines.push(line);
	h = i + 1;
	}
	}
	lines.push(String.fromCharCode.apply(null, array.subarray(h)));
	return lines;
	}
	var loadTextStl = function (buffer) {
	var lines = toLines(new Uint8Array(buffer));
	var index = 0;
	var scan = function (regexp) {
	while (lines[index].match(/^\s*$/)) index++;
	var r = lines[index].match(regexp);
	return r;
	};
	var scanOk = function (regexp) {
	var r = scan(regexp);
	if (!r) throw new Error(
	"not text stl: " + regexp.toString() +
	"=> (line " + (index - 1) + ")" +
	"[" + lines[index-1] + "]");
	index++;
	return r;
	}

	var facetReg = /^\s*facet\s+normal\s+([^\s]+)\s+([^\s]+)\s+([^\s]+)/;
	var vertexReg = /^\s*vertex\s+([^s]+)\s+([^\s]+)\s+([^\s]+)/;
	var geom = new THREE.Geometry();
	scanOk(/^\ssolid\s(.)/);
	while (!scan(/^\s*endsolid/)) {
	var normal = scanOk(facetReg);
	scanOk(/^\s*outer\s+loop/);
	var v1 = scanOk(vertexReg);
	var v2 = scanOk(vertexReg);
	var v3 = scanOk(vertexReg);
	scanOk(/\s*endloop/);
	scanOk(/\s*endfacet/);
	var base = geom.vertices.length;
	geom.vertices.push(m2vec3(v1));
	geom.vertices.push(m2vec3(v2));
	geom.vertices.push(m2vec3(v3));
	geom.faces.push(
	new THREE.Face3(base, base + 1, base + 2, m2vec3(normal)));
	}
	return geom;
	};

	return function (buffer) {
	try {
	console.log("load as text stl");
	return loadTextStl(buffer);
	} catch (ex) {
	console.log(ex);
	console.log("load as binary stl");
	return loadBinaryStl(buffer);
	}
	};
	})();