mirror of
https://github.com/Azgaar/Fantasy-Map-Generator.git
synced 2025-12-17 01:41:22 +01:00
399 lines
No EOL
16 KiB
JavaScript
399 lines
No EOL
16 KiB
JavaScript
(function (global, factory) {
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typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
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typeof define === 'function' && define.amd ? define(factory) :
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(global.Rivers = factory());
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}(this, (function () {'use strict';
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const generate = function(changeHeights = true) {
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TIME && console.time('generateRivers');
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Math.random = aleaPRNG(seed);
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const cells = pack.cells, p = cells.p, features = pack.features;
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const riversData = []; // rivers data
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cells.fl = new Uint16Array(cells.i.length); // water flux array
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cells.r = new Uint16Array(cells.i.length); // rivers array
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cells.conf = new Uint8Array(cells.i.length); // confluences array
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let riverNext = 1; // first river id is 1
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markupLand();
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const h = alterHeights();
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removeStoredLakeData();
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resolveDepressions(h);
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drainWater();
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defineRivers();
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cleanupLakeData();
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if (changeHeights) cells.h = Uint8Array.from(h); // apply changed heights as basic one
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TIME && console.timeEnd('generateRivers');
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// build distance field in cells from water (cells.t)
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function markupLand() {
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const q = t => cells.i.filter(i => cells.t[i] === t);
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for (let t = 2, queue = q(t); queue.length; t++, queue = q(t)) {
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queue.forEach(i => cells.c[i].forEach(c => {
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if (!cells.t[c]) cells.t[c] = t+1;
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}));
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}
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}
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// height with added t value to make map less depressed
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function alterHeights() {
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const h = Array.from(cells.h)
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.map((h, i) => h < 20 || cells.t[i] < 1 ? h : h + cells.t[i] / 100)
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.map((h, i) => h < 20 || cells.t[i] < 1 ? h : h + d3.mean(cells.c[i].map(c => cells.t[c])) / 10000);
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return h;
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}
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function removeStoredLakeData() {
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features.forEach(f => {
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delete f.flux;
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delete f.inlets;
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delete f.outlet;
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delete f.height;
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});
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}
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function drainWater() {
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const MIN_FLUX_TO_FORM_RIVER = 30;
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const land = cells.i.filter(i => h[i] >= 20).sort((a,b) => h[b] - h[a]);
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const lakeOutCells = new Uint16Array(cells.i.length); // to enumerate lake outlet positions
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features.forEach(f => {
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if (f.type !== "lake") return;
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const gridCell = cells.g[f.firstCell];
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// lake possible outlet: cell around with min height
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f.outCell = f.shoreline[d3.scan(f.shoreline, (a,b) => h[a] - h[b])];
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lakeOutCells[f.outCell] = f.i;
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// default flux: sum of precipition around lake first cell
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f.flux = rn(d3.sum(f.shoreline.map(c => grid.cells.prec[cells.g[c]])) / 2);
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// temperature and evaporation to detect closed lakes
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f.temp = f.cells < 6 ? grid.cells.temp[gridCell] : rn(d3.mean(f.shoreline.map(c => grid.cells.temp[cells.g[c]])), 1);
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const height = (f.height - 18) ** heightExponentInput.value; // height in meters
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const evaporation = (700 * (f.temp + .006 * height) / 50 + 75) / (80 - f.temp); // based on Penman formula, [1-11]
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f.evaporation = rn(evaporation * f.cells);
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});
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land.forEach(function(i) {
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cells.fl[i] += grid.cells.prec[cells.g[i]]; // flux from precipitation
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const x = p[i][0], y = p[i][1];
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// create lake outlet if flux > evaporation
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const lakes = !lakeOutCells[i] ? [] : features.filter(feature => i === feature.outCell && feature.flux > feature.evaporation);
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for (const lake of lakes) {
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const lakeCell = cells.c[i].find(c => h[c] < 20 && cells.f[c] === lake.i);
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cells.fl[lakeCell] += Math.max(lake.flux - lake.evaporation, 0); // not evaporated lake water drains to outlet
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// allow chain lakes to retain identity
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if (cells.r[lakeCell] !== lake.river) {
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const sameRiver = cells.c[lakeCell].some(c => cells.r[c] === lake.river);
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if (sameRiver) {
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cells.r[lakeCell] = lake.river;
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riversData.push({river: lake.river, cell: lakeCell, x: p[lakeCell][0], y: p[lakeCell][1], flux: cells.fl[lakeCell]});
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} else {
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cells.r[lakeCell] = riverNext;
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riversData.push({river: riverNext, cell: lakeCell, x: p[lakeCell][0], y: p[lakeCell][1], flux: cells.fl[lakeCell]});
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riverNext++;
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}
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}
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lake.outlet = cells.r[lakeCell];
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flowDown(i, cells.fl[i], cells.fl[lakeCell], lake.outlet);
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}
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// assign all tributary rivers to outlet basin
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for (let outlet = lakes[0]?.outlet, l = 0; l < lakes.length; l++) {
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lakes[l].inlets?.forEach(fork => riversData.find(r => r.river === fork).parent = outlet);
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}
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// near-border cell: pour water out of the screen
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if (cells.b[i] && cells.r[i]) {
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const to = [];
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const min = Math.min(y, graphHeight - y, x, graphWidth - x);
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if (min === y) {to[0] = x; to[1] = 0;} else
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if (min === graphHeight - y) {to[0] = x; to[1] = graphHeight;} else
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if (min === x) {to[0] = 0; to[1] = y;} else
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if (min === graphWidth - x) {to[0] = graphWidth; to[1] = y;}
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riversData.push({river: cells.r[i], cell: i, x: to[0], y: to[1], flux: cells.fl[i]});
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return;
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}
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// downhill cell (make sure it's not in the source lake)
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const min = lakeOutCells[i]
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? cells.c[i].filter(c => !lakes.map(lake => lake.i).includes(cells.f[c])).sort((a, b) => h[a] - h[b])[0]
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: cells.c[i].sort((a, b) => h[a] - h[b])[0];
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if (cells.fl[i] < MIN_FLUX_TO_FORM_RIVER) {
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if (h[min] >= 20) cells.fl[min] += cells.fl[i];
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return; // flux is too small to operate as river
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}
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// proclaim a new river
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if (!cells.r[i]) {
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cells.r[i] = riverNext;
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riversData.push({river: riverNext, cell: i, x, y, flux: cells.fl[i]});
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riverNext++;
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}
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flowDown(min, cells.fl[min], cells.fl[i], cells.r[i], i);
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});
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}
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function flowDown(toCell, toFlux, fromFlux, river, fromCell = 0) {
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if (cells.r[toCell]) {
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// downhill cell already has river assigned
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if (toFlux < fromFlux) {
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cells.conf[toCell] = cells.fl[toCell]; // mark confluence
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if (h[toCell] >= 20) riversData.find(r => r.river === cells.r[toCell]).parent = river; // min river is a tributary of current river
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cells.r[toCell] = river; // re-assign river if downhill part has less flux
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} else {
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cells.conf[toCell] += fromFlux; // mark confluence
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if (h[toCell] >= 20) riversData.find(r => r.river === river).parent = cells.r[toCell]; // current river is a tributary of min river
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}
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} else cells.r[toCell] = river; // assign the river to the downhill cell
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if (h[toCell] < 20) {
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// pour water to the water body
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const haven = fromCell ? cells.haven[fromCell] : toCell;
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riversData.push({river, cell: haven, x: p[toCell][0], y: p[toCell][1], flux: fromFlux});
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const waterBody = features[cells.f[toCell]];
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if (waterBody.type === "lake") {
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if (!waterBody.river || fromFlux > waterBody.enteringFlux) {
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waterBody.river = river;
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waterBody.enteringFlux = fromFlux;
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}
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waterBody.flux = waterBody.flux + fromFlux;
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waterBody.inlets ? waterBody.inlets.push(river) : waterBody.inlets = [river];
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}
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} else {
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// propagate flux and add next river segment
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cells.fl[toCell] += fromFlux;
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riversData.push({river, cell: toCell, x: p[toCell][0], y: p[toCell][1], flux: fromFlux});
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}
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}
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function defineRivers() {
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pack.rivers = []; // rivers data
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const riverPaths = [];
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for (let r = 1; r <= riverNext; r++) {
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const riverSegments = riversData.filter(d => d.river === r);
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if (riverSegments.length > 2) {
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const source = riverSegments[0].cell;
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const mouth = riverSegments[riverSegments.length-2].cell;
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const widthFactor = rn(.8 + Math.random() * .4, 1); // river width modifier [.8, 1.2]
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const sourceWidth = cells.h[source] >= 20 ? .1 : rn(Math.min(Math.max((cells.fl[source] / 500) ** .4, .5), 1.7), 2);
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const riverMeandered = addMeandering(riverSegments, sourceWidth * 10, .5);
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const [path, length, offset] = getPath(riverMeandered, widthFactor, sourceWidth);
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riverPaths.push([path, r]);
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const parent = riverSegments[0].parent || 0;
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const width = rn(offset ** 2, 2); // mounth width in km
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const discharge = last(riverSegments).flux; // in m3/s
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pack.rivers.push({i:r, source, mouth, discharge, length, width, widthFactor, sourceWidth, parent});
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} else {
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// remove too short rivers
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riverSegments.filter(s => cells.r[s.cell] === r).forEach(s => cells.r[s.cell] = 0);
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}
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}
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// draw rivers
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rivers.html(riverPaths.map(d => `<path id="river${d[1]}" d="${d[0]}"/>`).join(""));
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}
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function cleanupLakeData() {
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for (const feature of features) {
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if (feature.type !== "lake") continue;
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delete feature.river;
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delete feature.enteringFlux;
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delete feature.shoreline;
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delete feature.outCell;
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feature.height = rn(feature.height);
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const inlets = feature.inlets?.filter(r => pack.rivers.find(river => river.i === r));
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if (!inlets || !inlets.length) delete feature.inlets;
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else feature.inlets = inlets;
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const outlet = feature.outlet && pack.rivers.find(river => river.i === feature.outlet);
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if (!outlet) delete feature.outlet;
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}
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}
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}
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// depression filling algorithm (for a correct water flux modeling)
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const resolveDepressions = function(h) {
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const {cells, features} = pack;
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const ITERATIONS = 150;
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const lakes = features.filter(f => f.type === "lake");
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lakes.forEach(l => {
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const uniqueCells = new Set();
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l.vertices.forEach(v => pack.vertices.c[v].forEach(c => cells.h[c] >= 20 && uniqueCells.add(c)));
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l.shoreline = [...uniqueCells];
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l.height = 21;
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});
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const land = cells.i.filter(i => h[i] >= 20 && !cells.b[i]); // exclude near-border cells
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land.sort((a,b) => h[b] - h[a]); // highest cells go first
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let depressions = Infinity;
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for (let l = 0; depressions && l < ITERATIONS; l++) {
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depressions = 0;
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for (const l of lakes) {
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const minHeight = d3.min(l.shoreline.map(s => h[s]));
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if (minHeight >= 100 || l.height > minHeight) continue;
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l.height = minHeight + 1;
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depressions++;
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}
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for (const i of land) {
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const minHeight = d3.min(cells.c[i].map(c => cells.t[c] > 0 ? h[c] : pack.features[cells.f[c]].height || h[c]));
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if (minHeight >= 100 || h[i] > minHeight) continue;
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h[i] = minHeight + 1;
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depressions++;
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}
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}
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depressions && ERROR && console.error("Heightmap is depressed. Issues with rivers expected. Remove depressed areas to resolve");
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}
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// add more river points on 1/3 and 2/3 of length
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const addMeandering = function(segments, width = 1, meandering = .5) {
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const riverMeandered = []; // to store enhanced segments
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for (let s = 0; s < segments.length; s++, width++) {
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const sX = segments[s].x, sY = segments[s].y; // segment start coordinates
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const c = pack.cells.conf[segments[s].cell] || 0; // if segment is river confluence
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riverMeandered.push([sX, sY, c]);
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if (s+1 === segments.length) break; // do not meander last segment
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const eX = segments[s+1].x, eY = segments[s+1].y; // segment end coordinates
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const angle = Math.atan2(eY - sY, eX - sX);
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const sin = Math.sin(angle), cos = Math.cos(angle);
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const meander = meandering + 1 / width + Math.random() * Math.max(meandering - width / 100, 0);
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const dist2 = (eX - sX) ** 2 + (eY - sY) ** 2; // square distance between segment start and end
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if (width < 10 && (dist2 > 64 || (dist2 > 36 && segments.length < 6))) {
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// if dist2 is big or river is small add extra points at 1/3 and 2/3 of segment
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const p1x = (sX * 2 + eX) / 3 + -sin * meander;
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const p1y = (sY * 2 + eY) / 3 + cos * meander;
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const p2x = (sX + eX * 2) / 3 + sin * meander;
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const p2y = (sY + eY * 2) / 3 + cos * meander;
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riverMeandered.push([p1x, p1y], [p2x, p2y]);
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} else if (dist2 > 25 || segments.length < 6) {
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// if dist is medium or river is small add 1 extra middlepoint
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const p1x = (sX + eX) / 2 + -sin * meander;
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const p1y = (sY + eY) / 2 + cos * meander;
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riverMeandered.push([p1x, p1y]);
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}
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}
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return riverMeandered;
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}
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const getPath = function(points, widthFactor = 1, sourceWidth = .1) {
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let offset, extraOffset = sourceWidth; // starting river width (to make river source visible)
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const riverLength = points.reduce((s, v, i, p) => s + (i ? Math.hypot(v[0] - p[i-1][0], v[1] - p[i-1][1]) : 0), 0); // summ of segments length
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const widening = 1000 + riverLength * 30;
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const riverPointsLeft = [], riverPointsRight = []; // store points on both sides to build a valid polygon
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const last = points.length - 1;
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const factor = riverLength / points.length;
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// first point
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let x = points[0][0], y = points[0][1], c;
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let angle = Math.atan2(y - points[1][1], x - points[1][0]);
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let sin = Math.sin(angle), cos = Math.cos(angle);
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let xLeft = x + -sin * extraOffset, yLeft = y + cos * extraOffset;
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riverPointsLeft.push([xLeft, yLeft]);
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let xRight = x + sin * extraOffset, yRight = y + -cos * extraOffset;
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riverPointsRight.unshift([xRight, yRight]);
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// middle points
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for (let p = 1; p < last; p++) {
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x = points[p][0], y = points[p][1], c = points[p][2] || 0;
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const xPrev = points[p-1][0], yPrev = points[p - 1][1];
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const xNext = points[p+1][0], yNext = points[p + 1][1];
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angle = Math.atan2(yPrev - yNext, xPrev - xNext);
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sin = Math.sin(angle), cos = Math.cos(angle);
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offset = (Math.atan(Math.pow(p * factor, 2) / widening) / 2 * widthFactor) + extraOffset;
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const confOffset = Math.atan(c * 5 / widening);
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extraOffset += confOffset;
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xLeft = x + -sin * offset, yLeft = y + cos * (offset + confOffset);
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riverPointsLeft.push([xLeft, yLeft]);
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xRight = x + sin * offset, yRight = y + -cos * offset;
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riverPointsRight.unshift([xRight, yRight]);
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}
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// end point
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x = points[last][0], y = points[last][1], c = points[last][2];
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if (c) extraOffset += Math.atan(c * 10 / widening); // add extra width on river confluence
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angle = Math.atan2(points[last-1][1] - y, points[last-1][0] - x);
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sin = Math.sin(angle), cos = Math.cos(angle);
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xLeft = x + -sin * offset, yLeft = y + cos * offset;
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riverPointsLeft.push([xLeft, yLeft]);
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xRight = x + sin * offset, yRight = y + -cos * offset;
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riverPointsRight.unshift([xRight, yRight]);
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// generate polygon path and return
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lineGen.curve(d3.curveCatmullRom.alpha(0.1));
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const right = lineGen(riverPointsRight);
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let left = lineGen(riverPointsLeft);
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left = left.substring(left.indexOf("C"));
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return [round(right + left, 2), rn(riverLength, 2), offset];
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}
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const specify = function() {
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const rivers = pack.rivers;
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if (!rivers.length) return;
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Math.random = aleaPRNG(seed);
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const tresholdElement = Math.ceil(rivers.length * .15);
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const smallLength = rivers.map(r => r.length || 0).sort((a, b) => a-b)[tresholdElement];
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const smallType = {"Creek":9, "River":3, "Brook":3, "Stream":1}; // weighted small river types
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for (const r of rivers) {
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r.basin = getBasin(r.i);
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r.name = getName(r.mouth);
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const small = r.length < smallLength;
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r.type = r.parent && !(r.i%6) ? small ? "Branch" : "Fork" : small ? rw(smallType) : "River";
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}
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}
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const getName = function(cell) {
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return Names.getCulture(pack.cells.culture[cell]);
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}
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// remove river and all its tributaries
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const remove = function(id) {
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const cells = pack.cells;
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const riversToRemove = pack.rivers.filter(r => r.basin === id).map(r => r.i);
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riversToRemove.forEach(r => rivers.select("#river"+r).remove());
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cells.r.forEach((r, i) => {
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if (!r || !riversToRemove.includes(r)) return;
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cells.r[i] = 0;
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cells.fl[i] = grid.cells.prec[cells.g[i]];
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cells.conf[i] = 0;
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});
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pack.rivers = pack.rivers.filter(r => !riversToRemove.includes(r.i));
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}
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const getBasin = function(r) {
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const parent = pack.rivers.find(river => river.i === r)?.parent;
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if (!parent || r === parent) return r;
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return getBasin(parent);
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}
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return {generate, resolveDepressions, addMeandering, getPath, specify, getName, getBasin, remove};
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}))); |