31:T1135,meshToSTL = function(layer) { /** * Based on https://github.com/mrdoob/three.js/blob/a72347515fa34e892f7a9bfa66a34fdc0df55954/examples/js/exporters/STLExporter.js * Tested on r68 and r70 * @author kjlubick / https://github.com/kjlubick * @author kovacsv / http://kovacsv.hu/ * @author mrdoob / http://mrdoob.com/ */ // THREE.STLExporter = function() {}; // THREE.STLExporter.prototype = { // constructor: THREE.STLExporter, // parse: (function() { var vector = new THREE.Vector3(); var normalMatrixWorld = new THREE.Matrix3(); // return function(scene) { var output = ""; output += "solid exported\n"; layer.forEach(object => { // scene.traverse(function(object) { // if (object instanceof THREE.Mesh) { var geometry = object.geometry; var matrixWorld = object.matrixWorld; var mesh = object; if (geometry instanceof THREE.Geometry) { var vertices = geometry.vertices; var faces = geometry.faces; normalMatrixWorld.getNormalMatrix(matrixWorld); for (var i = 0, l = faces.length; i < l; i++) { var face = faces[i]; vector .copy(face.normal) .applyMatrix3(normalMatrixWorld) .normalize(); output += "\tfacet normal " + vector.x + " " + vector.y + " " + vector.z + "\n"; output += "\t\touter loop\n"; var indices = [face.a, face.b, face.c]; for (var j = 0; j < 3; j++) { var vertexIndex = indices[j]; if (mesh.geometry.skinIndices.length == 0) { vector.copy(vertices[vertexIndex]).applyMatrix4(matrixWorld); output += "\t\t\tvertex " + (+mesh.position.x + +vector.x) + " " + (+mesh.position.y + +vector.y) + " " + (+mesh.position.z + +vector.z) + "\n"; } else { vector.copy(vertices[vertexIndex]); //.applyMatrix4( matrixWorld ); // see https://github.com/mrdoob/three.js/issues/3187 const boneIndices = []; boneIndices[0] = mesh.geometry.skinIndices[vertexIndex].x; boneIndices[1] = mesh.geometry.skinIndices[vertexIndex].y; boneIndices[2] = mesh.geometry.skinIndices[vertexIndex].z; boneIndices[3] = mesh.geometry.skinIndices[vertexIndex].w; const weights = []; weights[0] = mesh.geometry.skinWeights[vertexIndex].x; weights[1] = mesh.geometry.skinWeights[vertexIndex].y; weights[2] = mesh.geometry.skinWeights[vertexIndex].z; weights[3] = mesh.geometry.skinWeights[vertexIndex].w; const inverses = []; inverses[0] = mesh.skeleton.boneInverses[boneIndices[0]]; inverses[1] = mesh.skeleton.boneInverses[boneIndices[1]]; inverses[2] = mesh.skeleton.boneInverses[boneIndices[2]]; inverses[3] = mesh.skeleton.boneInverses[boneIndices[3]]; const skinMatrices = []; skinMatrices[0] = mesh.skeleton.bones[boneIndices[0]].matrixWorld; skinMatrices[1] = mesh.skeleton.bones[boneIndices[1]].matrixWorld; skinMatrices[2] = mesh.skeleton.bones[boneIndices[2]].matrixWorld; skinMatrices[3] = mesh.skeleton.bones[boneIndices[3]].matrixWorld; var finalVector = new THREE.Vector4(); for (var k = 0; k < 4; k++) { var tempVector = new THREE.Vector4(vector.x, vector.y, vector.z); tempVector.multiplyScalar(weights[k]); //the inverse takes the vector into local bone space tempVector .applyMatrix4(inverses[k]) //which is then transformed to the appropriate world space .applyMatrix4(skinMatrices[k]); finalVector.add(tempVector); } output += "\t\t\tvertex " + finalVector.x + " " + finalVector.y + " " + finalVector.z + "\n"; } } output += "\t\tendloop\n"; output += "\tendfacet\n"; } } // } }); output += "endsolid exported\n"; return output; // }; // })() // }; // return "THE CODE - slightly adapted from https://gist.github.com/kjlubick/fb6ba9c51df63ba0951f"; }32:T46d,pointsToMesh = function(layer) { let tx = -0; let ty = -0; let scale = .01; const material = new THREE.MeshStandardMaterial({ color: 0xff3333 // opacity: 0.4 }); // just as with textures, we need to put colors into linear color space material.color.convertSRGBToLinear(); var extrudeSettings = { steps: 4, depth: .1, bevelEnabled: false // bevelThickness: 1, // bevelSize: .1, // bevelOffset: 0, // bevelSegments: 1 }; let meshes = layer.map((points, i) => { let shape = new THREE.Shape(); extrudeSettings.depth = Math.abs(Math.sin(((Math.PI * i) / layer.length) * 8)) * 0.4 + 0.05; // console.log(tx + points[0].x * scale); shape.moveTo(tx + points[0].x * scale, ty + points[0].y * scale); points.forEach(d => { let x = tx + d.x * scale; let y = ty + d.y * scale; shape.lineTo(x, y); }); // shape.lineTo(tx + points[0].nx * scale, ty + points[0].ny * scale); let geometry = new THREE.ExtrudeGeometry(shape, extrudeSettings); let mesh = new THREE.Mesh(geometry, material); return mesh; }); return meshes; }33:[] 2f:{"title":"Graphene Moiré 3D","cells":[{"id":0,"value":"md`# Graphene Moiré 3D\n\nIt was [recently discovered](https://www.quantamagazine.org/how-twisted-graphene-became-the-big-thing-in-physics-20190430/) that ultrathin sheets of *graphene*—hexagonal lattices of carbon atoms—can be stacked and twisted to form superconductors. With each successive layer in the stack, a small twist of 1.1° around a common axis yields the conditions for superconductivity. \n\nI decided to make a notebook to explore this phenomenon. I wondered in particular about this \"magic angle\" of 1.1°. While this and other twist factors of the form:`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1571,"value":"tex.block`\\theta_n = \\frac{11\\cdot2^n}{225}\\cdot360\\degree`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1579,"value":"md `yield periodic alignments of [some coordinates](https://en.wikipedia.org/wiki/Integer_triangle#Integer_triangles_with_a_120%C2%B0_angle) when n is an integer, continuous transformation of *n* is pretty captivating for *every* value of *θ*. Press *Replay* to cycle through twist factors from 0° to 60°, and use the sliders below to control the twist, height, intricacy, stroke-width, scale, and tapering of the honeycomb.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1638,"value":"viewof replay = html`