mirror of
https://github.com/Azgaar/Fantasy-Map-Generator.git
synced 2025-12-16 17:31:24 +01:00
520 lines
17 KiB
JavaScript
520 lines
17 KiB
JavaScript
"use strict";
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window.Rivers = (function () {
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const generate = function (allowErosion = true) {
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TIME && console.time("generateRivers");
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Math.random = aleaPRNG(seed);
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const {cells, features} = pack;
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const riversData = {}; // rivers data
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const riverParents = {};
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const addCellToRiver = function (cell, river) {
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if (!riversData[river]) riversData[river] = [cell];
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else riversData[river].push(cell);
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};
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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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const h = alterHeights();
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Lakes.detectCloseLakes(h);
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resolveDepressions(h);
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drainWater();
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defineRivers();
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calculateConfluenceFlux();
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Lakes.cleanupLakeData();
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if (allowErosion) {
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cells.h = Uint8Array.from(h); // apply gradient
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downcutRivers(); // downcut river beds
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}
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TIME && console.timeEnd("generateRivers");
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function drainWater() {
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const MIN_FLUX_TO_FORM_RIVER = 30;
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const cellsNumberModifier = (pointsInput.dataset.cells / 10000) ** 0.25;
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const prec = grid.cells.prec;
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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 = Lakes.defineClimateData(h);
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land.forEach(function (i) {
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cells.fl[i] += prec[cells.g[i]] / cellsNumberModifier; // add flux from precipitation
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// create lake outlet if lake is not in deep depression and flux > evaporation
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const lakes = lakeOutCells[i]
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? features.filter(feature => i === feature.outCell && feature.flux > feature.evaporation)
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: [];
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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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addCellToRiver(lakeCell, lake.river);
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} else {
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cells.r[lakeCell] = riverNext;
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addCellToRiver(lakeCell, riverNext);
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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[lakeCell], lake.outlet);
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}
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// assign all tributary rivers to outlet basin
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const outlet = lakes[0]?.outlet;
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for (const lake of lakes) {
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if (!Array.isArray(lake.inlets)) continue;
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for (const inlet of lake.inlets) {
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riverParents[inlet] = outlet;
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}
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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]) return addCellToRiver(-1, cells.r[i]);
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// downhill cell (make sure it's not in the source lake)
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let min = null;
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if (lakeOutCells[i]) {
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const filtered = cells.c[i].filter(c => !lakes.map(lake => lake.i).includes(cells.f[c]));
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min = filtered.sort((a, b) => h[a] - h[b])[0];
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} else if (cells.haven[i]) {
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min = cells.haven[i];
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} else {
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min = cells.c[i].sort((a, b) => h[a] - h[b])[0];
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}
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// cells is depressed
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if (h[i] <= h[min]) return;
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// debug
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// .append("line")
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// .attr("x1", pack.cells.p[i][0])
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// .attr("y1", pack.cells.p[i][1])
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// .attr("x2", pack.cells.p[min][0])
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// .attr("y2", pack.cells.p[min][1])
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// .attr("stroke", "#333")
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// .attr("stroke-width", 0.2);
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if (cells.fl[i] < MIN_FLUX_TO_FORM_RIVER) {
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// flux is too small to operate as a river
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if (h[min] >= 20) cells.fl[min] += cells.fl[i];
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return;
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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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addCellToRiver(i, riverNext);
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riverNext++;
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}
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flowDown(min, cells.fl[i], cells.r[i]);
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});
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}
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function flowDown(toCell, fromFlux, river) {
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const toFlux = cells.fl[toCell] - cells.conf[toCell];
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const toRiver = cells.r[toCell];
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if (toRiver) {
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// downhill cell already has river assigned
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if (fromFlux > toFlux) {
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cells.conf[toCell] += cells.fl[toCell]; // mark confluence
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if (h[toCell] >= 20) riverParents[toRiver] = 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) riverParents[river] = toRiver; // 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 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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if (!waterBody.inlets) waterBody.inlets = [river];
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else waterBody.inlets.push(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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}
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addCellToRiver(toCell, river);
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}
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function defineRivers() {
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// re-initialize rivers and confluence arrays
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cells.r = new Uint16Array(cells.i.length);
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cells.conf = new Uint16Array(cells.i.length);
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pack.rivers = [];
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const defaultWidthFactor = rn(1 / (pointsInput.dataset.cells / 10000) ** 0.25, 2);
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const mainStemWidthFactor = defaultWidthFactor * 1.2;
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for (const key in riversData) {
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const riverCells = riversData[key];
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if (riverCells.length < 3) continue; // exclude tiny rivers
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const riverId = +key;
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for (const cell of riverCells) {
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if (cell < 0 || cells.h[cell] < 20) continue;
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// mark real confluences and assign river to cells
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if (cells.r[cell]) cells.conf[cell] = 1;
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else cells.r[cell] = riverId;
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}
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const source = riverCells[0];
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const mouth = riverCells[riverCells.length - 2];
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const parent = riverParents[key] || 0;
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const widthFactor = !parent || parent === riverId ? mainStemWidthFactor : defaultWidthFactor;
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const meanderedPoints = addMeandering(riverCells);
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const discharge = cells.fl[mouth]; // m3 in second
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const length = getApproximateLength(meanderedPoints);
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const sourceWidth = getSourceWidth(cells.fl[source]);
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const width = getWidth(
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getOffset({
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flux: discharge,
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pointIndex: meanderedPoints.length,
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widthFactor,
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startingWidth: sourceWidth
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})
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);
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pack.rivers.push({
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i: riverId,
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source,
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mouth,
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discharge,
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length,
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width,
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widthFactor,
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sourceWidth,
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parent,
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cells: riverCells
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});
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}
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}
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function downcutRivers() {
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const MAX_DOWNCUT = 5;
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for (const i of pack.cells.i) {
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if (cells.h[i] < 35) continue; // don't donwcut lowlands
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if (!cells.fl[i]) continue;
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const higherCells = cells.c[i].filter(c => cells.h[c] > cells.h[i]);
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const higherFlux = higherCells.reduce((acc, c) => acc + cells.fl[c], 0) / higherCells.length;
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if (!higherFlux) continue;
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const downcut = Math.floor(cells.fl[i] / higherFlux);
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if (downcut) cells.h[i] -= Math.min(downcut, MAX_DOWNCUT);
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}
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}
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function calculateConfluenceFlux() {
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for (const i of cells.i) {
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if (!cells.conf[i]) continue;
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const sortedInflux = cells.c[i]
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.filter(c => cells.r[c] && h[c] > h[i])
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.map(c => cells.fl[c])
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.sort((a, b) => b - a);
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cells.conf[i] = sortedInflux.reduce((acc, flux, index) => (index ? acc + flux : acc), 0);
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}
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}
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};
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// add distance to water value to land cells to make map less depressed
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const alterHeights = () => {
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const {h, c, t} = pack.cells;
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return Array.from(h).map((h, i) => {
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if (h < 20 || t[i] < 1) return h;
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return h + t[i] / 100 + d3.mean(c[i].map(c => t[c])) / 10000;
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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 maxIterations = +document.getElementById("resolveDepressionsStepsOutput").value;
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const checkLakeMaxIteration = maxIterations * 0.85;
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const elevateLakeMaxIteration = maxIterations * 0.75;
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const height = i => features[cells.f[i]].height || h[i]; // height of lake or specific cell
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const lakes = features.filter(f => f.type === "lake");
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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[a] - h[b]); // lowest cells go first
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const progress = [];
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let depressions = Infinity;
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let prevDepressions = null;
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for (let iteration = 0; depressions && iteration < maxIterations; iteration++) {
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if (progress.length > 5 && d3.sum(progress) > 0) {
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// bad progress, abort and set heights back
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h = alterHeights();
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depressions = progress[0];
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break;
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}
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depressions = 0;
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if (iteration < checkLakeMaxIteration) {
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for (const l of lakes) {
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if (l.closed) continue;
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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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if (iteration > elevateLakeMaxIteration) {
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l.shoreline.forEach(i => (h[i] = cells.h[i]));
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l.height = d3.min(l.shoreline.map(s => h[s])) - 1;
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l.closed = true;
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continue;
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}
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depressions++;
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l.height = minHeight + 0.2;
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}
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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 => height(c)));
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if (minHeight >= 100 || h[i] > minHeight) continue;
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depressions++;
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h[i] = minHeight + 0.1;
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}
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prevDepressions !== null && progress.push(depressions - prevDepressions);
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prevDepressions = depressions;
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}
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depressions && WARN && console.warn(`Unresolved depressions: ${depressions}. Edit heightmap to fix`);
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};
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// add points at 1/3 and 2/3 of a line between adjacents river cells
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const addMeandering = function (riverCells, riverPoints = null, meandering = 0.5) {
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const {fl, h} = pack.cells;
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const meandered = [];
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const lastStep = riverCells.length - 1;
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const points = getRiverPoints(riverCells, riverPoints);
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let step = h[riverCells[0]] < 20 ? 1 : 10;
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for (let i = 0; i <= lastStep; i++, step++) {
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const cell = riverCells[i];
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const isLastCell = i === lastStep;
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const [x1, y1] = points[i];
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meandered.push([x1, y1, fl[cell]]);
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if (isLastCell) break;
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const nextCell = riverCells[i + 1];
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const [x2, y2] = points[i + 1];
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if (nextCell === -1) {
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meandered.push([x2, y2, fl[cell]]);
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break;
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}
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const dist2 = (x2 - x1) ** 2 + (y2 - y1) ** 2; // square distance between cells
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if (dist2 <= 25 && riverCells.length >= 6) continue;
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const meander = meandering + 1 / step + Math.max(meandering - step / 100, 0);
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const angle = Math.atan2(y2 - y1, x2 - x1);
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const sinMeander = Math.sin(angle) * meander;
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const cosMeander = Math.cos(angle) * meander;
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if (step < 20 && (dist2 > 64 || (dist2 > 36 && riverCells.length < 5))) {
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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 = (x1 * 2 + x2) / 3 + -sinMeander;
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const p1y = (y1 * 2 + y2) / 3 + cosMeander;
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const p2x = (x1 + x2 * 2) / 3 + sinMeander / 2;
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const p2y = (y1 + y2 * 2) / 3 - cosMeander / 2;
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meandered.push([p1x, p1y, 0], [p2x, p2y, 0]);
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} else if (dist2 > 25 || riverCells.length < 6) {
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// if dist is medium or river is small add 1 extra middlepoint
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const p1x = (x1 + x2) / 2 + -sinMeander;
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const p1y = (y1 + y2) / 2 + cosMeander;
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meandered.push([p1x, p1y, 0]);
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}
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}
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return meandered;
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};
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const getRiverPoints = (riverCells, riverPoints) => {
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if (riverPoints) return riverPoints;
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const {p} = pack.cells;
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return riverCells.map((cell, i) => {
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if (cell === -1) return getBorderPoint(riverCells[i - 1]);
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return p[cell];
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});
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};
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const getBorderPoint = i => {
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const [x, y] = pack.cells.p[i];
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const min = Math.min(y, graphHeight - y, x, graphWidth - x);
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if (min === y) return [x, 0];
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else if (min === graphHeight - y) return [x, graphHeight];
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else if (min === x) return [0, y];
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return [graphWidth, y];
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};
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const FLUX_FACTOR = 500;
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const MAX_FLUX_WIDTH = 1;
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const LENGTH_FACTOR = 200;
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const LENGTH_STEP_WIDTH = 1 / LENGTH_FACTOR;
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const LENGTH_PROGRESSION = [1, 1, 2, 3, 5, 8, 13, 21, 34].map(n => n / LENGTH_FACTOR);
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const getOffset = ({flux, pointIndex, widthFactor, startingWidth}) => {
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if (pointIndex === 0) return startingWidth;
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const fluxWidth = Math.min(flux ** 0.7 / FLUX_FACTOR, MAX_FLUX_WIDTH);
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const lengthWidth = pointIndex * LENGTH_STEP_WIDTH + (LENGTH_PROGRESSION[pointIndex] || LENGTH_PROGRESSION.at(-1));
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return widthFactor * (lengthWidth + fluxWidth) + startingWidth;
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};
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const getSourceWidth = flux => rn(Math.min(flux ** 0.9 / FLUX_FACTOR, MAX_FLUX_WIDTH), 2);
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// build polygon from a list of points and calculated offset (width)
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const getRiverPath = (points, widthFactor, startingWidth) => {
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lineGen.curve(d3.curveCatmullRom.alpha(0.1));
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const riverPointsLeft = [];
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const riverPointsRight = [];
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let flux = 0;
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for (let pointIndex = 0; pointIndex < points.length; pointIndex++) {
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const [x0, y0] = points[pointIndex - 1] || points[pointIndex];
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const [x1, y1, pointFlux] = points[pointIndex];
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const [x2, y2] = points[pointIndex + 1] || points[pointIndex];
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if (pointFlux > flux) flux = pointFlux;
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const offset = getOffset({flux, pointIndex, widthFactor, startingWidth});
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const angle = Math.atan2(y0 - y2, x0 - x2);
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const sinOffset = Math.sin(angle) * offset;
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const cosOffset = Math.cos(angle) * offset;
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riverPointsLeft.push([x1 - sinOffset, y1 + cosOffset]);
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riverPointsRight.push([x1 + sinOffset, y1 - cosOffset]);
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}
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const right = lineGen(riverPointsRight.reverse());
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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, 1);
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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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for (const river of rivers) {
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river.basin = getBasin(river.i);
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river.name = getName(river.mouth);
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river.type = getType(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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// weighted arrays of river type names
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const riverTypes = {
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main: {
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big: {River: 1},
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small: {Creek: 9, River: 3, Brook: 3, Stream: 1}
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},
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fork: {
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big: {Fork: 1},
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small: {Branch: 1}
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}
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};
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let smallLength = null;
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const getType = function ({i, length, parent}) {
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if (smallLength === null) {
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const threshold = Math.ceil(pack.rivers.length * 0.15);
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smallLength = pack.rivers.map(r => r.length || 0).sort((a, b) => a - b)[threshold];
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}
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const isSmall = length < smallLength;
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const isFork = each(3)(i) && parent && parent !== i;
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return rw(riverTypes[isFork ? "fork" : "main"][isSmall ? "small" : "big"]);
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};
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const getApproximateLength = points => {
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const length = points.reduce((s, v, i, p) => s + (i ? Math.hypot(v[0] - p[i - 1][0], v[1] - p[i - 1][1]) : 0), 0);
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return rn(length, 2);
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};
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// Real mouth width examples: Amazon 6000m, Volga 6000m, Dniepr 3000m, Mississippi 1300m, Themes 900m,
|
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// Danube 800m, Daugava 600m, Neva 500m, Nile 450m, Don 400m, Wisla 300m, Pripyat 150m, Bug 140m, Muchavets 40m
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|
const getWidth = offset => rn((offset / 1.5) ** 1.8, 2); // mouth width in km
|
|
|
|
// remove river and all its tributaries
|
|
const remove = function (id) {
|
|
const cells = pack.cells;
|
|
const riversToRemove = pack.rivers.filter(r => r.i === id || r.parent === id || r.basin === id).map(r => r.i);
|
|
riversToRemove.forEach(r => rivers.select("#river" + r).remove());
|
|
cells.r.forEach((r, i) => {
|
|
if (!r || !riversToRemove.includes(r)) return;
|
|
cells.r[i] = 0;
|
|
cells.fl[i] = grid.cells.prec[cells.g[i]];
|
|
cells.conf[i] = 0;
|
|
});
|
|
pack.rivers = pack.rivers.filter(r => !riversToRemove.includes(r.i));
|
|
};
|
|
|
|
const getBasin = function (r) {
|
|
const parent = pack.rivers.find(river => river.i === r)?.parent;
|
|
if (!parent || r === parent) return r;
|
|
return getBasin(parent);
|
|
};
|
|
|
|
const getNextId = function (rivers) {
|
|
return rivers.length ? Math.max(...rivers.map(r => r.i)) + 1 : 1;
|
|
};
|
|
|
|
return {
|
|
generate,
|
|
alterHeights,
|
|
resolveDepressions,
|
|
addMeandering,
|
|
getRiverPath,
|
|
specify,
|
|
getName,
|
|
getType,
|
|
getBasin,
|
|
getWidth,
|
|
getOffset,
|
|
getSourceWidth,
|
|
getApproximateLength,
|
|
getRiverPoints,
|
|
remove,
|
|
getNextId
|
|
};
|
|
})();
|