refactor river fendering

modules/ui/tools.js

@@ -530,92 +530,111 @@ function toggleAddRiver() {
 }
 
 function addRiverOnClick() {
-  const cells = pack.cells;
+  const {cells, rivers} = pack;
   const point = d3.mouse(this);
   let i = findCell(point[0], point[1]);
-  if (cells.r[i] || cells.h[i] < 20 || cells.b[i]) return;
 
-  const dataRiver = []; // to store river points
-  let river = +getNextId("river").slice(5); // river id
-  cells.fl[i] = grid.cells.prec[cells.g[i]]; // initial flux
+  if (cells.r[i]) return tip("There already a river here", false, "error");
+  if (cells.h[i] < 20) return tip("Cannot create river in water cell", false, "error");
+  if (cells.b[i]) return;
+
+  const riverPoints = [];
+  let riverId = +getNextId("river").slice(5);
+
+  const initialFlux = grid.cells.prec[cells.g[i]];
+  cells.fl[i] = initialFlux;
 
   const h = Rivers.alterHeights();
-  Lakes.prepareLakeData(h);
   Rivers.resolveDepressions(h);
 
   while (i) {
-    cells.r[i] = river;
+    cells.r[i] = riverId;
     const [x, y] = cells.p[i];
-    dataRiver.push({x, y, cell: i});
+    riverPoints.push({x, y, cell: i});
 
     const min = cells.c[i].sort((a, b) => h[a] - h[b])[0]; // downhill cell
     if (h[i] <= h[min]) return tip(`Cell ${i} is depressed, river cannot flow further`, false, "error");
 
     const [tx, ty] = cells.p[min];
 
+    // pour to water body
     if (h[min] < 20) {
-      // pour to water body
-      dataRiver.push({x: tx, y: ty, cell: i});
+      riverPoints.push({x: tx, y: ty, cell: i});
+
+      const feature = pack.features[cells.f[min]];
+      if (feature.type === "lake") {
+        riverPoints[0].parent = feature.outlet || 0;
+        feature.inlets ? feature.inlets.push(riverId) : (feature.inlets = [riverId]);
+      }
       break;
     }
 
+    // continue propagation if min cell has no river
     if (!cells.r[min]) {
-      // continue if next cell has not river
       cells.fl[min] += cells.fl[i];
       i = min;
       continue;
     }
 
     // handle case when lowest cell already has a river
-    const r = cells.r[min];
-    const riverCells = cells.i.filter(i => cells.r[i] === r);
+    const oldRiverId = cells.r[min];
+    const riverCells = cells.i.filter(i => cells.r[i] === oldRiverId);
     const riverCellsUpper = riverCells.filter(i => h[i] > h[min]);
 
-    // finish new river if old river is longer
-    if (dataRiver.length <= riverCellsUpper.length) {
+    // create new river as a tributary
+    if (riverPoints.length <= riverCellsUpper.length) {
       cells.conf[min] += cells.fl[i];
-      dataRiver.push({x: tx, y: ty, cell: min});
-      dataRiver[0].parent = r; // new river is tributary
+      riverPoints.push({x: tx, y: ty, cell: min});
+      riverPoints[0].parent = oldRiverId;
       break;
     }
 
-    // extend old river
-    rivers.select("#river" + r).remove();
-    cells.i.filter(i => cells.r[i] === river).forEach(i => (cells.r[i] = r));
-    riverCells.forEach(i => (cells.r[i] = 0));
-    river = r;
-    cells.fl[min] = cells.fl[i] + grid.cells.prec[cells.g[min]];
-    i = min;
+    // continue old river
+    document.getElementById("river" + oldRiverId)?.remove();
+    cells.i.filter(i => cells.r[i] === riverId).forEach(i => (cells.r[i] = oldRiverId));
+    const oldRiver = rivers.find(river => river.i === oldRiverId);
+    oldRiver?.points.forEach(([x, y, cell]) => {
+      riverPoints.push({x, y, cell});
+      cells.fl[cell] += cells.fl[i];
+    });
+    riverId = oldRiverId;
+
+    break;
   }
 
-  const points = Rivers.addMeandering(dataRiver, 1, 0.5);
-  const widthFactor = rn(0.8 + Math.random() * 0.4, 1); // river width modifier [.8, 1.2]
+  const river = rivers.find(r => r.i === riverId);
   const sourceWidth = 0.1;
-  const [path, length, offset] = Rivers.getPath(points, widthFactor, sourceWidth);
-  rivers
+  const widthFactor = river.widthFactor || rn(0.8 + Math.random() * 0.4, 1);
+
+  const riverCells = riverPoints.map(point => point.cell);
+  const riverMeandered = Rivers.addMeandering(riverCells, sourceWidth * 10, 0.5);
+  const [path, length, offset] = Rivers.getPath(riverMeandered, widthFactor, sourceWidth);
+  viewbox
+    .select("#rivers")
     .append("path")
     .attr("d", path)
-    .attr("id", "river" + river);
+    .attr("id", "river" + riverId);
 
   // add new river to data or change extended river attributes
-  const r = pack.rivers.find(r => r.i === river);
-  const mouth = last(dataRiver).cell;
+  const source = riverPoints[0].cell;
+  const mouth = last(riverPoints).cell;
   const discharge = cells.fl[mouth]; // in m3/s
+  const width = rn(offset ** 2, 2); // mounth width in km
 
-  if (r) {
-    r.source = dataRiver[0].cell;
-    r.length = length;
-    r.discharge = discharge;
+  if (river) {
+    river.source = source;
+    river.length = length;
+    river.discharge = discharge;
+    river.width = width;
+    river.points = points;
   } else {
-    const parent = dataRiver[0].parent || 0;
-    const basin = Rivers.getBasin(river);
-    const source = dataRiver[0].cell;
-    const width = rn(offset ** 2, 2); // mounth width in km
+    const parent = riverPoints[0].parent || 0;
+    const basin = Rivers.getBasin(parent);
     const name = Rivers.getName(mouth);
-    const smallLength = pack.rivers.map(r => r.length || 0).sort((a, b) => a - b)[Math.ceil(pack.rivers.length * 0.15)];
+    const smallLength = rivers.map(r => r.length || 0).sort((a, b) => a - b)[Math.ceil(pack.rivers.length * 0.15)];
     const type = length < smallLength ? rw({Creek: 9, River: 3, Brook: 3, Stream: 1}) : "River";
 
-    pack.rivers.push({i: river, source, mouth, discharge, length, width, widthFactor, sourceWidth, parent, basin, name, type});
+    rivers.push({i: riverId, source, mouth, discharge, length, width, widthFactor, sourceWidth, parent, cells: riverCells, basin, name, type});
   }
 
   if (d3.event.shiftKey === false) {