Create n-dimentional plexispheres!

plexisphere.js

(function() {
	var arr = function(length, fill) {
		var arr = [];
		for (var i = 0; i < length; i++)
		{
			arr.push(fill);
		}
		return arr;
	};
	
	var arrbut = function(arr, but) {
		var out = [];
		for (var i in arr) {
			if (i != but)
			{
				out.push(arr[i]);
			}
		}
		return out;
	}
	
	var mixverts = function(verts) {
		var dim = verts[0].length;
		var vert = arr(dim, 0);
		for (var i in verts)
		{
			for (var j in verts[i])
			{
				vert[j] += verts[i][j] / verts.length;
			}
		}
		return vert;
	}
	
	var simplex = function(dim) {
		var geo = {verts: [], facets: []};
		for (var i = 0; i < dim + 1; i++)
		{
			geo.verts.push(arr(dim, null));
			for (var j = i + 1; j < dim; j++)
			{
				geo.verts[i][j] = 0;
			}
		}
		//https://en.wikipedia.org/wiki/Simplex#Cartesian_coordinates_for_regular_n-dimensional_simplex_in_Rn
		var dotsolve = 1;
		var dotrem = -1 / dim;
		for (var i = 0; i < dim; i++)
		{
			var ssum = 0;
			for (var j = 0; j < i; j++)
			{
				ssum += geo.verts[i][j] * geo.verts[i][j];
			}
			var pythsolve = geo.verts[i][i] = Math.sqrt(1 - ssum);
			dotsolve = dotrem / pythsolve;
			for (var j = i + 1; j < dim + 1; j++)
			{
				geo.verts[j][i] = dotsolve;
			}
			dotrem -= dotsolve * dotsolve;
		}
		for (var i = 0; i < dim + 1; i++)
		{
			var facet = [];
			for (var j = 0; j < dim + 1; j++)
			{
				if (i != j)
				{
					facet.push(j);
				}
			}
			geo.facets.push(facet);
		}
		return geo;
	};
	
	var sub = {
		center: function (geo, dim) {
			var newfacets = [];
			for (var i in geo.facets)
			{
				var facet = geo.facets[i];
				var vertind = geo.verts.length;
				var verts = [];
				for (var j = 0; j < dim; j++)
				{
					var newfacet = [];
					for (var k = 0; k < dim; k++)
					{
						verts.push(geo.verts[facet[j]]);
						if (k != j)
						{
							newfacet.push(facet[k]);
						}
					}
					newfacet.push(vertind);
					newfacets.push(newfacet);
				}
				geo.verts.push(mixverts(verts));
			}
			geo.facets = newfacets;
			return geo;
		},
		edge: function (geo, dim) {
			var edges = {};
			for (var i in geo.facets)
			{
				var facet = geo.facets[i];
				var newfacet = [];
				for (var j = 0; j < facet.length; j++)
				{
					var sel = arrbut(facet, j);
					sel.sort();
					var edge = edges[sel];
					if (!edge)
					{
						var verts = [];
						for (var k in sel)
						{
							verts.push(geo.verts[sel[k]]);
						}
						edge = geo.verts.length;
						edges[sel] = edge;
						geo.verts.push(mixverts(verts));
					}
					newfacet.push(edge);
				}
				for (var j = 0; j < facet.length; j++)
				{
					var nextfacet = [facet[j]];
					for (var k = 0; k < facet.length; k++)
					{
						if (k != j)
						{
							nextfacet.push(newfacet[k]);
						}
					}
					geo.facets.push(nextfacet);
				}
				geo.facets[i] = newfacet;
			}
			return geo;
		}
	};
	
	var norm = function (vert)
	{
		var ssum = 0;
		for (var i in vert)
		{
			ssum += vert[i] * vert[i];
		}
		ssum = Math.sqrt(ssum);
		for (var i in vert)
		{
			vert[i] /= ssum;
		}
		return vert;
	}

	plexisphere = function(pos, radius, subdiv, mode, normmode) {
		var dim = pos.length;
		if (!sub[mode])
		{
			console.log("fail");
			return;
		}
		var geo = simplex(dim);
		for (var i = 0; i < subdiv; i++)
		{
			geo = sub[mode](geo, dim);
			if (normmode == "each")
			{
				for (var j in geo.verts)
				{
					norm(geo.verts[j]);
				}
			}
		}
		if (normmode == "last")
		{
			for (var i in geo.verts)
			{
				norm(geo.verts[i]);
			}
		}
		for (var i in geo.verts)
		{
			for (var j = 0; j < dim; j++)
			{
				geo.verts[i][j] *= radius;
				geo.verts[i][j] += pos[j];
			}
		}
		return geo;
	};
})();

var toobj = function(geo)
{
	var obj = "";
	for (var i in geo.verts)
	{
		var vert = geo.verts[i];
		obj += "v";
		for (var j in vert)
		{
			obj += " " + vert[j];
		}
		obj += "\n";
	}
	for (var i in geo.facets)
	{
		obj += "\n";
		var facet = geo.facets[i];
		obj += "f";
		for (var j in facet)
		{
			obj += " " + (facet[j] + 1);
		}
	}
	return obj;
}

http://prntscr.com/8277zo
http://prntscr.com/8278db

toobj(plexisphere([0, 0, 0], 5, 6, "edge", "last")); //nice 3-d plexisphere as a .obj model
plexisphere([0, 0, 0, 0], 5, 3, "center", "each"); //wtf 5-d thing