From 03809e56abd0f2ae39566d51e1bc1129c9e82475 Mon Sep 17 00:00:00 2001
From: max <maxganiev@yandex.com>
Date: Tue, 23 Aug 2022 21:34:33 +0300
Subject: [PATCH] refactor: curve and shorten 2-points routes

---
 src/layers/renderers/drawRoutes.ts | 41 ++++++++++++++++++++++++++++--
 src/utils/debugUtils.ts            | 10 ++++----
 src/utils/lineUtils.ts             |  4 +++
 3 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/src/layers/renderers/drawRoutes.ts b/src/layers/renderers/drawRoutes.ts
index 2c9751f4..1518dd8d 100644
--- a/src/layers/renderers/drawRoutes.ts
+++ b/src/layers/renderers/drawRoutes.ts
@@ -1,11 +1,12 @@
 import * as d3 from "d3";
 
+import {getNormal} from "utils/lineUtils";
 import {round} from "utils/stringUtils";
 
 const lineGenTypeMap: {[key in IRoute["type"]]: d3.CurveFactory | d3.CurveFactoryLineOnly} = {
   road: d3.curveCatmullRom.alpha(0.1),
   trail: d3.curveCatmullRom.alpha(0.1),
-  sea: d3.curveBundle.beta(1)
+  sea: d3.curveBasis
 };
 
 export function drawRoutes() {
@@ -22,7 +23,7 @@ export function drawRoutes() {
 
   for (const {i, type, cells} of pack.routes) {
     if (type !== "sea") straightenPathAngles(cells); // mutates points
-    const pathPoints = cells.map(cellId => points[cellId]);
+    const pathPoints = getPathPoints(cells);
 
     lineGen.curve(lineGenTypeMap[type]);
     const path = round(lineGen(pathPoints)!, 1);
@@ -79,4 +80,40 @@ export function drawRoutes() {
       }
     }
   }
+
+  function getPathPoints(cellIds: number[]): TPoints {
+    const pathPoints = cellIds.map(cellId => points[cellId]);
+
+    if (pathPoints.length === 2) {
+      // curve and shorten 2-points line
+      const [[x1, y1], [x2, y2]] = pathPoints;
+
+      const middleX = (x1 + x2) / 2;
+      const middleY = (y1 + y2) / 2;
+
+      // add shifted point at the middle to curve the line a bit
+      const NORMAL_LENGTH = 0.3;
+      const normal = getNormal([x1, y1], [x2, y2]);
+      const sign = cellIds[0] % 2 ? 1 : -1;
+      const normalX = middleX + NORMAL_LENGTH * Math.cos(normal) * sign;
+      const normalY = middleY + NORMAL_LENGTH * Math.sin(normal) * sign;
+
+      // make line shorter to avoid overlapping with other lines
+      const SHORT_LINE_LENGTH_MODIFIER = 0.8;
+      const distX = x2 - x1;
+      const distY = y2 - y1;
+      const nx1 = x1 + distX * SHORT_LINE_LENGTH_MODIFIER;
+      const ny1 = y1 + distY * SHORT_LINE_LENGTH_MODIFIER;
+      const nx2 = x2 - distX * SHORT_LINE_LENGTH_MODIFIER;
+      const ny2 = y2 - distY * SHORT_LINE_LENGTH_MODIFIER;
+
+      return [
+        [nx1, ny1],
+        [normalX, normalY],
+        [nx2, ny2]
+      ];
+    }
+
+    return pathPoints;
+  }
 }
diff --git a/src/utils/debugUtils.ts b/src/utils/debugUtils.ts
index 20a3113c..623d66a5 100644
--- a/src/utils/debugUtils.ts
+++ b/src/utils/debugUtils.ts
@@ -1,5 +1,7 @@
 // utils to be used for debugging (not in PROD)
 
+import {getNormal} from "./lineUtils";
+
 export function drawPoint([x, y]: TPoint, {radius = 1, color = "red"} = {}) {
   debug.append("circle").attr("cx", x).attr("cy", y).attr("r", radius).attr("fill", color);
 }
@@ -10,7 +12,7 @@ export function drawPolygon(
 ) {
   debug
     .append("polyline")
-    .attr("points", [...points, points[0]])
+    .attr("points", [...points, points[0]].join(" "))
     .attr("fill", fill)
     .attr("fill-opacity", fillOpacity)
     .attr("stroke", stroke)
@@ -28,10 +30,8 @@ export function drawLine([x1, y1]: TPoint, [x2, y2]: TPoint, {stroke = "#444", s
     .attr("stroke-width", strokeWidth);
 }
 
-export function drawArrow([x1, y1]: TPoint, [x2, y2]: TPoint, {width = 1, color = "#444"} = {}): void {
-  const angle = Math.atan2(y2 - y1, x2 - x1);
-  const normal = angle + Math.PI / 2;
-
+export function drawArrow([x1, y1]: TPoint, [x2, y2]: TPoint, {width = 1, color = "#444"} = {}) {
+  const normal = getNormal([x1, y1], [x2, y2]);
   const [xMid, yMid] = [(x1 + x2) / 2, (y1 + y2) / 2];
 
   const [xLeft, yLeft] = [xMid + width * Math.cos(normal), yMid + width * Math.sin(normal)];
diff --git a/src/utils/lineUtils.ts b/src/utils/lineUtils.ts
index bb0f6008..0d837f12 100644
--- a/src/utils/lineUtils.ts
+++ b/src/utils/lineUtils.ts
@@ -74,3 +74,7 @@ export function filterOutOfCanvasPoints(points: TPoints) {
 
   return points.filter((_, i) => filterOutCanvasPoint(i));
 }
+
+export function getNormal([x1, y1]: TPoint, [x2, y2]: TPoint) {
+  return Math.atan2(y1 - y2, x1 - x2) + Math.PI / 2;
+}