feat(effects): extinguish fire with water/rain and ambient SFX volume

Water and rain erase fire under a tight brush hit radius; add looping fire/rain ambients and an Effects sound slider that also scales one-shot effect SFX.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/shared/fieldEffectEraser.ts

@@ -47,13 +47,34 @@ function minDistToEraserStroke(
   return Math.sqrt(bestSq);
 }
 
+/**
+ * `inclusive` — ластик: радиус кисти + радиус инстанса (снять всё пятно).
+ * `brush` — вода/дождь по огню: укороченный радиус кисти (спрайты огня шире radiusN, иначе гасится «издалека»).
+ */
+export type FieldEraseHitMode = 'inclusive' | 'brush';
+
+/** Доля радиуса кисти для гашения огня водой/дождём (центр кисти ближе к точке огня). */
+export const FIRE_EXTINGUISH_BRUSH_SCALE = 0.38;
+
+function eraseThresholdN(
+  eraserRadiusN: number,
+  instRadiusN: number,
+  hitMode: FieldEraseHitMode,
+): number {
+  if (hitMode === 'brush') {
+    return Math.max(0.006, eraserRadiusN * FIRE_EXTINGUISH_BRUSH_SCALE);
+  }
+  return eraserRadiusN + instRadiusN;
+}
+
 function isPointErased(
   p: { x: number; y: number },
   instRadiusN: number,
   eraserPoints: readonly { x: number; y: number }[],
   eraserRadiusN: number,
+  hitMode: FieldEraseHitMode,
 ): boolean {
-  const threshold = eraserRadiusN + instRadiusN;
+  const threshold = eraseThresholdN(eraserRadiusN, instRadiusN, hitMode);
   return minDistToEraserStroke(p, eraserPoints) <= threshold;
 }
 
@@ -62,11 +83,12 @@ function splitKeptPointRuns(
   eraserPoints: readonly { x: number; y: number }[],
   eraserRadiusN: number,
   instRadiusN: number,
+  hitMode: FieldEraseHitMode,
 ): NPoint[][] {
   const runs: NPoint[][] = [];
   let current: NPoint[] = [];
   for (const p of points) {
-    if (isPointErased(p, instRadiusN, eraserPoints, eraserRadiusN)) {
+    if (isPointErased(p, instRadiusN, eraserPoints, eraserRadiusN, hitMode)) {
       if (current.length > 0) {
         runs.push(current);
         current = [];
@@ -83,14 +105,19 @@ function isFieldEffect(inst: EffectInstance): inst is FieldEffectInstance {
   return inst.type === 'fog' || inst.type === 'fire' || inst.type === 'rain' || inst.type === 'water';
 }
 
+export type FieldEffectType = FieldEffectInstance['type'];
+
 /** Стирает эффекты поля (туман/дождь/огонь/вода) кистью, как «Кисть Открытия» для затемнения. */
 export function applyFieldEffectEraserStroke(
   instances: readonly EffectInstance[],
   eraserPoints: readonly NPoint[],
   eraserRadiusN: number,
   makeId: (prefix: string) => string,
+  targetTypes?: readonly FieldEffectType[],
+  hitMode: FieldEraseHitMode = 'inclusive',
 ): EffectInstance[] {
   if (eraserPoints.length === 0) return [...instances];
+  const typeFilter = targetTypes && targetTypes.length > 0 ? new Set(targetTypes) : null;
 
   const out: EffectInstance[] = [];
   for (const inst of instances) {
@@ -98,8 +125,12 @@ export function applyFieldEffectEraserStroke(
       out.push(inst);
       continue;
     }
+    if (typeFilter && !typeFilter.has(inst.type)) {
+      out.push(inst);
+      continue;
+    }
 
-    const runs = splitKeptPointRuns(inst.points, eraserPoints, eraserRadiusN, inst.radiusN);
+    const runs = splitKeptPointRuns(inst.points, eraserPoints, eraserRadiusN, inst.radiusN, hitMode);
     if (runs.length === 0) continue;
     if (runs.length === 1 && runs[0]?.length === inst.points.length) {
       out.push(inst);