A threejs version of this d3 contour plot. A 2D array of values is defined on grid with coordinates xgrid and ygrid. threejs splits each cell into 2 triangle faces. The color of each vertex is set using the same d3 color scale as before.
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February 17, 2019 20:26
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threejs surface from a structured grid of data
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| license: mit |
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| <!DOCTYPE html> | |
| <div id="container"></div> | |
| <script src="https://threejs.org/build/three.js"></script> | |
| <script src="https://threejs.org/examples/js/controls/OrbitControls.js"></script> | |
| <script src="https://d3js.org/d3.v4.min.js"></script> | |
| <script src="https://d3js.org/d3-scale-chromatic.v1.min.js"></script> | |
| <script> | |
| // Structured (n * m) grid of data. Point coordinates are (xgrid, ygrid) | |
| var n = 101, m = 101; | |
| var nverts = n*m; | |
| var values = new Array(n * m); | |
| var xgrid = new Array(n * m); | |
| var ygrid = new Array(n * m); | |
| for (var j = 0., k = 0; j < m; ++j) { | |
| for (var i = 0.; i < n; ++i, ++k) { | |
| xgrid[k] = i; | |
| ygrid[k] = 25*Math.sin(i*Math.PI/50) + j; | |
| values[k] = Math.pow( (xgrid[k]-50), 2 ) + Math.pow( (ygrid[k]-50), 2 ); | |
| } | |
| } | |
| // Obtain centre of grid and scale factors | |
| var xmin = d3.min(xgrid); | |
| var xmax = d3.max(xgrid); | |
| var xmid = 0.5*(xmin+xmax); | |
| var xrange = xmax-xmin; | |
| var ymin = d3.min(ygrid); | |
| var ymax = d3.max(ygrid); | |
| var ymid = 0.5*(ymin+ymax); | |
| var yrange = ymax-ymin; | |
| var zmin = d3.min(values); | |
| var zmax = d3.max(values); | |
| var zmid = 0.5*(zmin+zmax); | |
| var zrange = zmax-zmin; | |
| var scalefac = 1.2/Math.max(xrange, yrange); | |
| var scalefacz = 0.5/zrange; | |
| // Use d3 for color scale | |
| var color = d3.scaleLinear() | |
| .domain(d3.extent(values)) | |
| .interpolate(function() { return d3.interpolateRdBu; }); | |
| // Initialise threejs geometry | |
| var geometry = new THREE.Geometry(); | |
| // Add grid vertices to geometry | |
| for (var k = 0; k < nverts; ++k) { | |
| var newvert= new THREE.Vector3( (xgrid[k] - xmid) * scalefac, (ygrid[k] - ymid) * scalefac, (values[k] - zmid) * scalefacz); | |
| geometry.vertices.push(newvert); | |
| } | |
| // Add cell faces (2 traingles per cell) to geometry | |
| for (var j = 0; j < m-1; j++){ | |
| for (var i = 0; i < n-1; i++){ | |
| var n0 = j*n + i; | |
| var n1 = n0 + 1; | |
| var n2 = (j+1)*n + i + 1; | |
| var n3 = n2 - 1; | |
| face1= new THREE.Face3(n0,n1,n2); | |
| face2= new THREE.Face3(n2,n3,n0); | |
| face1.vertexColors[0]=new THREE.Color(color(values[n0])); | |
| face1.vertexColors[1]=new THREE.Color(color(values[n1])); | |
| face1.vertexColors[2]=new THREE.Color(color(values[n2])); | |
| face2.vertexColors[0]=new THREE.Color(color(values[n2])); | |
| face2.vertexColors[1]=new THREE.Color(color(values[n3])); | |
| face2.vertexColors[2]=new THREE.Color(color(values[n0])); | |
| geometry.faces.push(face1); | |
| geometry.faces.push(face2); | |
| } | |
| } | |
| // Compute normals for shading | |
| geometry.computeFaceNormals(); | |
| geometry.computeVertexNormals(); | |
| // Use MeshPhongMaterial for a reflective surface | |
| var material = new THREE.MeshPhongMaterial( { | |
| side: THREE.DoubleSide, | |
| color: 0xffffff, | |
| vertexColors: THREE.VertexColors, | |
| specular: 0x050505, | |
| shininess: 100., | |
| emissive: 0x111111, | |
| }); | |
| // Initialise threejs scene | |
| var scene = new THREE.Scene(); | |
| // Add Mesh to scene | |
| scene.add( new THREE.Mesh( geometry, material ) ); | |
| // Create renderer | |
| var renderer = new THREE.WebGLRenderer({alpha:true, antialias:true}); | |
| renderer.setPixelRatio( window.devicePixelRatio ); | |
| renderer.setSize( 500, 500 ); | |
| // Set target DIV for rendering | |
| var container = document.getElementById( 'container' ); | |
| container.appendChild( renderer.domElement ); | |
| // Define the camera | |
| var camera = new THREE.PerspectiveCamera( 45, 1, 0.1, 10 ); | |
| camera.position.z = 2; | |
| // Add controls | |
| var controls = new THREE.OrbitControls( camera, renderer.domElement ); | |
| controls.addEventListener( 'change', function(){ | |
| renderer.render(scene,camera); // re-render if controls move/zoom | |
| } ); | |
| controls.enableZoom = true; | |
| // Light above | |
| var light = new THREE.PointLight( 0xffffff); | |
| light.position.set( 0, 0, 3 ); | |
| scene.add( light ); | |
| // Light below | |
| var light = new THREE.PointLight( 0xffffff); | |
| light.position.set( 0, 0, -3 ); | |
| scene.add( light ); | |
| // Ambient light | |
| var light = new THREE.AmbientLight( 0x222222 ); | |
| scene.add( light ); | |
| // Make initial call to render scene | |
| renderer.render( scene, camera ); | |
| </script> |
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