Coloured links for 24-cell

fourDShape.js

@@ -19,16 +19,26 @@ function fourDtoV3(x, y, z, w, rotations) {
 
 class FourDShape extends THREE.Group {
 
-	constructor(node_ms, link_m, structure) {
+	constructor(node_ms, link_ms, structure) {
 		super();
 		this.node_ms = node_ms;
-		this.link_m = link_m;
+		this.link_ms = link_ms;
 		this.nodes4 = structure.nodes;
 		this.nodes3 = {};
 		this.links = structure.links;
 		this.initShapes();
 	}
 
+	// if a node/link has no label, use the 0th material
+
+	getMaterial(entity, materials) {
+		if( "label" in entity ) {
+			return materials[entity.label];
+		} else {
+			return materials[0];
+		}
+	}
+
 	makeNode(material, v3) {
 		const geometry = new THREE.SphereGeometry(NODE_SIZE);
 		const sphere = new THREE.Mesh(geometry, material);
@@ -37,14 +47,14 @@ class FourDShape extends THREE.Group {
 		return sphere;
 	}
 
-	makeLink(link) {
+	makeLink(material, link) {
 		const n1 = this.nodes3[link.source].v3;
 		const n2 = this.nodes3[link.target].v3;
 		const length = n1.distanceTo(n2);
 		const centre = new THREE.Vector3();
 		centre.lerpVectors(n1, n2, 0.5);
 		const geometry = new THREE.CylinderGeometry(LINK_SIZE, LINK_SIZE, 1);
-		const cyl = new THREE.Mesh(geometry, this.link_m);
+		const cyl = new THREE.Mesh(geometry, material);
 		const edge = new THREE.Group();
 		edge.add(cyl);
 		edge.position.copy(centre);
@@ -70,14 +80,15 @@ class FourDShape extends THREE.Group {
 	initShapes() {
 		for( const n of this.nodes4 ) {
 			const v3 = fourDtoV3(n.x, n.y, n.z, n.w, []);
-			const material = this.node_ms[n.label];
+			const material = this.getMaterial(n, this.node_ms);
 			this.nodes3[n.id] = {
 				v3: v3,
 				object: this.makeNode(material, v3)
 			};
 		}
 		for( const l of this.links ) {
-			l.object = this.makeLink(l);
+			const material = this.getMaterial(l, this.link_ms);
+			l.object = this.makeLink(material, l);
 		}
 	}
 

main.js

@@ -108,17 +108,13 @@ document.body.appendChild( renderer.domElement );
 
 const struct = POLYTOPES.cell24();
 
-// TODO = automate going from struct labels to colours, this now only
-// works with the 24-cell
+const node_ms = [
+	new THREE.MeshStandardMaterial( { color: 0x990000 } ),
+	new THREE.MeshStandardMaterial( { color: 0x009900 } ),
+	new THREE.MeshStandardMaterial( { color: 0x000099 } ),
+];
 
-const node_ms = {};
-
-node_ms["RED"] = new THREE.MeshStandardMaterial( { color: 0x990044 } );
-node_ms["GREEN"] = new THREE.MeshStandardMaterial( { color: 0xffffee } );
-node_ms["BLUE"] = new THREE.MeshStandardMaterial( { color: 0x101010 } );
-
-for( const label in node_ms ) {
-	const node_m = node_ms[label];
+for( const node_m of node_ms ) {
 	node_m.roughness = 0.2;
 
 	if( NODE_OPACITY < 1.0 ) {
@@ -127,21 +123,24 @@ for( const label in node_ms ) {
 	}
 }
 
+const link_ms = [
+	new THREE.MeshStandardMaterial( { color: 0x999900 } ),
+	new THREE.MeshStandardMaterial( { color: 0x009999 } ),
+	new THREE.MeshStandardMaterial( { color: 0x990099 } ),
+	];
 
-const link_m = new THREE.MeshStandardMaterial(
-	{ color: 0xb0b0b0 } );
-
-
+for( const link_m of link_ms ) {
 	link_m.metalness = 0.4;
 	link_m.roughness = 0.0;
 
-if( LINK_OPACITY < 1.0 ) {
-	link_m.transparent = true;	
-	link_m.opacity = LINK_OPACITY;
+	if( NODE_OPACITY < 1.0 ) {
+		node_m.transparent = true;	
+		node_m.opacity = NODE_OPACITY;
+	}
 }
 
 
-const shape = new FourDShape(node_ms, link_m, struct);
+const shape = new FourDShape(node_ms, link_ms, struct);
 
 scene.add(shape);
 

polytopes.js

@@ -1,5 +1,7 @@
 const r5 = Math.sqrt(5);
 
+// if nodes or links have no label, use the first material in the
+// list
 
 export const CELL5 = {
 	nodes: [
@@ -127,11 +129,19 @@ export const TESSERACT = {
 // this was done manually and I'm not sure if it's right
 
 const CELL24_INDEXING = {
-	x: { y: 'RED', z: 'BLUE', w: 'GREEN' },
-	y: { z: 'GREEN', w: 'BLUE' },
-	z: { w: 'RED' } 
+	x: { y: 0, z: 2, w: 1 },
+	y: { z: 1, w: 2 },
+	z: { w: 0 },
 };
 
+// note that this depends on the colour mapping in main.js, yuck
+
+const CELL24_LINK_INDEXING = {
+	0: { 1: 0, 2: 2 },
+	1: { 0: 0, 2: 1 },
+	2: { 0: 2, 1: 1 },
+}
+
 function make_24cell_vertices() {
 	const axes = [ 'x', 'y', 'z', 'w' ];
 	const nodes = [];
@@ -179,7 +189,8 @@ function make_24cell_edges(nodes) {
 			const fp = ids.join(',');
 			if( !seen[fp] ) {
 				seen[fp] = true;
-				links.push({ id: id, source: n1.id, target: n2.id });
+				const label = CELL24_LINK_INDEXING[n1.label][n2.label];
+				links.push({ id: id, label: label, source: n1.id, target: n2.id });
 			}
 		}
 	}
@@ -190,6 +201,9 @@ export const cell24 = () => {
 	const nodes = make_24cell_vertices();
 	const links = make_24cell_edges(nodes);
 
-	return { nodes: nodes, links: links, labels: [ "RED", "GREEN", "BLUE" ] };
+	return {
+		nodes: nodes,
+		links: links
+	};
 }