feat(control) 多角色控制

systems/ControlMode.js

@@ -0,0 +1,24 @@
+export const CONTROL_MODE = {
+  SINGLE: 'single',
+  GROUP: 'group',
+  JOYSTICK: 'joystick'
+};
+
+export let activeUnit = null;
+export let selectedUnits = [];
+
+export function setActiveUnit(unit) {
+  activeUnit = unit;
+  selectedUnits = unit ? [unit] : [];
+}
+
+export function addToSelection(unit) {
+  if (!selectedUnits.includes(unit)) {
+    selectedUnits.push(unit);
+  }
+}
+
+export function clearSelection() {
+  activeUnit = null;
+  selectedUnits = [];
+}