Typescript

src/hooks/useGridSnapping.ts

@@ -0,0 +1,93 @@
+import Vector2 from "../helpers/Vector2";
+import {
+  getCellLocation,
+  getNearestCellCoordinates,
+  getCellCorners,
+} from "../helpers/grid";
+
+import useSetting from "./useSetting";
+
+import {
+  useGrid,
+  useGridOffset,
+  useGridCellPixelSize,
+  useGridCellPixelOffset,
+} from "../contexts/GridContext";
+
+/**
+ * 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: number | undefined = undefined,
+  useCorners: boolean = true
+) {
+  const [defaultSnappingSensitivity] = useSetting<number>(
+    "map.gridSnappingSensitivity"
+  );
+  let gridSnappingSensitivity =
+    snappingSensitivity === undefined
+      ? defaultSnappingSensitivity
+      : snappingSensitivity;
+
+  const grid = useGrid();
+  const gridOffset = useGridOffset();
+  const gridCellPixelSize = useGridCellPixelSize();
+  const gridCellPixelOffset = useGridCellPixelOffset();
+
+  /**
+   * @param {Vector2} node The node to snap
+   */
+  function snapPositionToGrid(position: Vector2) {
+    // Account for grid offset
+    let offsetPosition = Vector2.subtract(
+      Vector2.subtract(position, gridOffset),
+      gridCellPixelOffset
+    );
+    const nearsetCell = getNearestCellCoordinates(
+      grid,
+      offsetPosition.x,
+      offsetPosition.y,
+      gridCellPixelSize
+    );
+    const cellPosition = getCellLocation(
+      grid,
+      nearsetCell.x,
+      nearsetCell.y,
+      gridCellPixelSize
+    );
+    const cellCorners = getCellCorners(
+      grid,
+      cellPosition.x,
+      cellPosition.y,
+      gridCellPixelSize
+    );
+
+    const snapPoints = [cellPosition];
+    if (useCorners) {
+      snapPoints.push(...cellCorners);
+    }
+
+    for (let snapPoint of snapPoints) {
+      const distanceToSnapPoint = Vector2.distance(offsetPosition, snapPoint);
+      if (
+        distanceToSnapPoint <
+        Vector2.componentMin(gridCellPixelSize) * gridSnappingSensitivity
+      ) {
+        // Reverse grid offset
+        let offsetSnapPoint = Vector2.add(
+          Vector2.add(snapPoint, gridOffset),
+          gridCellPixelOffset
+        );
+        return offsetSnapPoint;
+      }
+    }
+
+    return position;
+  }
+
+  return snapPositionToGrid;
+}
+
+export default useGridSnapping;