init with react+axum+spacetimedb

src/data/encounterTransition.ts

@@ -0,0 +1,125 @@
+import { GameState } from '../types';
+import { getFacingTowardPlayer, getMonsterGroupAnchorX, PLAYER_BASE_X_METERS } from './hostileNpcs';
+
+function roundMeters(value: number) {
+  return Number(value.toFixed(2));
+}
+
+function lerp(start: number, end: number, progress: number) {
+  return roundMeters(start + ((end - start) * progress));
+}
+
+export function hasEncounterEntity(state: Pick<GameState, 'sceneHostileNpcs' | 'currentEncounter'>) {
+  return state.sceneHostileNpcs.length > 0 || Boolean(state.currentEncounter);
+}
+
+export function buildEncounterEntryState(
+  finalState: GameState,
+  entryX: number,
+): GameState {
+  if (finalState.sceneHostileNpcs.length > 0) {
+    const anchorX = getMonsterGroupAnchorX(finalState.sceneHostileNpcs);
+    return {
+      ...finalState,
+      sceneHostileNpcs: finalState.sceneHostileNpcs.map(monster => {
+        const offset = monster.xMeters - anchorX;
+        const xMeters = roundMeters(entryX + offset);
+        return {
+          ...monster,
+          xMeters,
+          animation: 'move' as const,
+          facing: getFacingTowardPlayer(xMeters, PLAYER_BASE_X_METERS),
+        };
+      }),
+      currentEncounter: null,
+    };
+  }
+
+  if (finalState.currentEncounter) {
+    return {
+      ...finalState,
+      currentEncounter: {
+        ...finalState.currentEncounter,
+        xMeters: entryX,
+      },
+      sceneHostileNpcs: [],
+    };
+  }
+
+  return finalState;
+}
+
+export function buildEncounterTransitionState(
+  finalState: GameState,
+  sourceState: Pick<GameState, 'sceneHostileNpcs' | 'currentEncounter'>,
+): GameState {
+  if (finalState.sceneHostileNpcs.length > 0) {
+    const sourceById = new Map(sourceState.sceneHostileNpcs.map(monster => [monster.id, monster]));
+    return {
+      ...finalState,
+      sceneHostileNpcs: finalState.sceneHostileNpcs.map(monster => {
+        const sourceMonster = sourceById.get(monster.id);
+        const xMeters = sourceMonster?.xMeters ?? monster.xMeters;
+        return {
+          ...monster,
+          xMeters,
+          animation: 'move' as const,
+          facing: getFacingTowardPlayer(xMeters, PLAYER_BASE_X_METERS),
+        };
+      }),
+      currentEncounter: null,
+    };
+  }
+
+  if (finalState.currentEncounter) {
+    return {
+      ...finalState,
+      currentEncounter: {
+        ...finalState.currentEncounter,
+        xMeters: sourceState.currentEncounter?.xMeters ?? finalState.currentEncounter.xMeters,
+      },
+      sceneHostileNpcs: [],
+    };
+  }
+
+  return finalState;
+}
+
+export function interpolateEncounterTransitionState(
+  startState: Pick<GameState, 'sceneHostileNpcs' | 'currentEncounter'>,
+  finalState: GameState,
+  progress: number,
+): GameState {
+  if (finalState.sceneHostileNpcs.length > 0) {
+    const startById = new Map(startState.sceneHostileNpcs.map(monster => [monster.id, monster]));
+    return {
+      ...finalState,
+      sceneHostileNpcs: finalState.sceneHostileNpcs.map(monster => {
+        const startMonster = startById.get(monster.id);
+        const xMeters = lerp(startMonster?.xMeters ?? monster.xMeters, monster.xMeters, progress);
+        return {
+          ...monster,
+          xMeters,
+          animation: progress < 1 ? ('move' as const) : monster.animation,
+          facing: getFacingTowardPlayer(xMeters, PLAYER_BASE_X_METERS),
+        };
+      }),
+      currentEncounter: null,
+    };
+  }
+
+  if (finalState.currentEncounter) {
+    const startX = startState.currentEncounter?.xMeters ?? finalState.currentEncounter.xMeters ?? 0;
+    const endX = finalState.currentEncounter.xMeters ?? startX;
+    return {
+      ...finalState,
+      currentEncounter: {
+        ...finalState.currentEncounter,
+        xMeters: lerp(startX, endX, progress),
+      },
+      sceneHostileNpcs: [],
+    };
+  }
+
+  return finalState;
+}