From 1f2c70a6122eb8a1bc03825a925feebc887c6497 Mon Sep 17 00:00:00 2001
From: Mitchell McCaffrey <mitchemmc@gmail.com>
Date: Sat, 19 Jun 2021 09:36:00 +1000
Subject: [PATCH] Change measure tool to use full snapping to grid center and
 add exact euclidean measurements

---
 src/components/map/MapMeasure.js |  5 ++++-
 src/helpers/grid.js              |  9 +++------
 src/hooks/useGridSnapping.js     | 13 ++++++++++---
 3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/src/components/map/MapMeasure.js b/src/components/map/MapMeasure.js
index f9318c9..5e5acc6 100644
--- a/src/components/map/MapMeasure.js
+++ b/src/components/map/MapMeasure.js
@@ -44,7 +44,10 @@ function MapMeasure({ map, active }) {
 
   const gridScale = parseGridScale(active && grid.measurement.scale);
 
-  const snapPositionToGrid = useGridSnapping();
+  const snapPositionToGrid = useGridSnapping(
+    grid.measurement.type === "euclidean" ? 0 : 1,
+    false
+  );
 
   useEffect(() => {
     if (!active) {
diff --git a/src/helpers/grid.js b/src/helpers/grid.js
index b7612c8..57ecd2a 100644
--- a/src/helpers/grid.js
+++ b/src/helpers/grid.js
@@ -289,10 +289,7 @@ export function gridDistance(grid, a, b, cellSize) {
   const bCoord = getNearestCellCoordinates(grid, b.x, b.y, cellSize);
   if (grid.type === "square") {
     if (grid.measurement.type === "chebyshev") {
-      return Math.max(
-        Math.abs(aCoord.x - bCoord.x),
-        Math.abs(aCoord.y - bCoord.y)
-      );
+      return Vector2.max(Vector2.abs(Vector2.subtract(aCoord, bCoord)));
     } else if (grid.measurement.type === "alternating") {
       // Alternating diagonal distance like D&D 3.5 and Pathfinder
       const delta = Vector2.abs(Vector2.subtract(aCoord, bCoord));
@@ -300,7 +297,7 @@ export function gridDistance(grid, a, b, cellSize) {
       const min = Vector2.min(delta);
       return max - min + Math.floor(1.5 * min);
     } else if (grid.measurement.type === "euclidean") {
-      return Vector2.distance(aCoord, bCoord);
+      return Vector2.length(Vector2.divide(Vector2.subtract(a, b), cellSize));
     } else if (grid.measurement.type === "manhattan") {
       return Math.abs(aCoord.x - bCoord.x) + Math.abs(aCoord.y - bCoord.y);
     }
@@ -316,7 +313,7 @@ export function gridDistance(grid, a, b, cellSize) {
         2
       );
     } else if (grid.measurement.type === "euclidean") {
-      return Vector2.distance(aCoord, bCoord);
+      return Vector2.length(Vector2.divide(Vector2.subtract(a, b), cellSize));
     }
   }
 }
diff --git a/src/hooks/useGridSnapping.js b/src/hooks/useGridSnapping.js
index 9c1a85c..aa52040 100644
--- a/src/hooks/useGridSnapping.js
+++ b/src/hooks/useGridSnapping.js
@@ -17,12 +17,16 @@ import {
 /**
  * Returns a function that when called will snap a node to the current grid
  * @param {number=} snappingSensitivity 1 = Always snap, 0 = never snap if undefined the default user setting will be used
+ * @param {boolean=} useCorners Snap to grid cell corners
  */
-function useGridSnapping(snappingSensitivity) {
+function useGridSnapping(snappingSensitivity, useCorners = true) {
   const [defaultSnappingSensitivity] = useSetting(
     "map.gridSnappingSensitivity"
   );
-  snappingSensitivity = snappingSensitivity || defaultSnappingSensitivity;
+  snappingSensitivity =
+    snappingSensitivity === undefined
+      ? defaultSnappingSensitivity
+      : snappingSensitivity;
 
   const grid = useGrid();
   const gridOffset = useGridOffset();
@@ -57,7 +61,10 @@ function useGridSnapping(snappingSensitivity) {
       gridCellPixelSize
     );
 
-    const snapPoints = [cellPosition, ...cellCorners];
+    const snapPoints = [cellPosition];
+    if (useCorners) {
+      snapPoints.push(...cellCorners);
+    }
 
     for (let snapPoint of snapPoints) {
       const distanceToSnapPoint = Vector2.distance(offsetPosition, snapPoint);