room overlays draft

src/scripts/plugins/room-overlays.js

@@ -0,0 +1,47 @@
+/*
+Draw roof layers over a room that hides interiors until the player enters them.
+
+HOW TO USE:
+1. Import plugin in bipsi
+2. In a desired room, create an event tagged "room-overlay"
+3. Add to that event a "location" field called "room-overlay" for each desired layer, pointing to the room to draw over this one.
+4. In the rooms to be overlaid, set walls in any place where the layer should be hidden if the player is standing there.
+*/
+
+wrap.after(BipsiPlayback.prototype, "addLayersToScene", async function(scene, dest, frame) {
+    if (this.ended)
+        return;
+
+    const avatar = getEventById(this.data, this.avatarId);
+    const room = roomFromEvent(this.data, avatar);
+
+    const overlay = room.events.find((event) => IS_TAGGED(event, "room-overlay"));
+
+    if (!overlay)
+        return;
+
+    const locations = FIELDS(overlay, "room-overlay", "location");
+    const tileToFrame = makeTileToFrameMap(this.data.tiles, frame);
+
+    function upscaler(func) {
+        return () => {
+            fillRendering2D(TEMP_ROOM);
+            func();
+            dest.drawImage(TEMP_ROOM.canvas, 0, 0, 256, 256);
+        };
+    }
+
+    for (const location of locations) {
+        const room = getRoomById(this.data, location.room);
+        const palette = getPaletteById(this.data, room.palette);
+        const tileset = this.stateManager.resources.get(this.data.tileset);
+
+        const [fx, fy] = avatar.position;
+        const solid = cellIsSolid(room, fx, fy);
+
+        if (solid)
+            continue;
+
+        scene.push({ layer: 2.5, func: upscaler(() => drawTilemapLayer(TEMP_ROOM, tileset, tileToFrame, palette, room)) });
+    }
+});