Fix sprite flicker broken with multi-camera setups (#1357)

* Fix sprite flicker broken with multi-camera setups

The flicker visibility was toggled per draw() call, so with 2 cameras
(e.g., default + minimap) it toggled twice per frame, canceling out.

Replace the per-frame boolean toggle with time-based flickering:
- Track elapsed time in update() instead of toggling state
- Compute visibility in draw() from elapsed time (read-only, no mutation)
- Consistent ~15 flashes/sec regardless of frame rate or camera count

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Address review: extract constant, fix initial visibility, reset elapsed

- Extract FLICKER_INTERVAL_MS constant (33ms, ~15 flashes/sec)
- Invert parity check so first frame starts visible, not invisible
- Always reset elapsed when flicker() is called (even if already flickering)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: obiot

packages/melonjs/CHANGELOG.md

@@ -31,6 +31,13 @@
 - Path2D: fix `quadraticCurveTo()` and `bezierCurveTo()` segment count — was using `arcResolution` directly (2 segments), now computes adaptive segment count based on control polygon length for smooth curves.
 - Text: fix textBaseline y offset for multiline text — "bottom"/"middle" used single line height instead of total text height, causing misaligned bounding boxes
 - BitmapText: fix bounds offset direction for textAlign/textBaseline — bounds were shifted in the wrong direction for "right"/"center"/"bottom"/"middle"
+- BitmapText: fix bounding box width — last glyph now uses `max(xadvance, xoffset + width)` to capture full visual extent
+- BitmapText: fix bounding box height — uses actual glyph extents (`maxBottom - minTop`) instead of `capHeight` which was too short for glyphs with descenders
+- BitmapText: fix baseline positioning — "middle"/"bottom"/"alphabetic"/"ideographic" shifts now use real glyph metrics and total text height, correctly centering and aligning text on baseline reference points
+- BitmapText: fix bounding box y offset — box starts at first visible glyph pixel (`glyphMinTop * scale`) instead of draw origin
+- BitmapText: optimize bounds calculation — precompute `glyphMinTop`/`glyphMaxBottom` once in font parsing; cache `measureText` results in `setText`/`resize` instead of recomputing on every `updateBounds`
+- Camera2d: fix floating containers with Infinity bounds not rendering — containers with default `Infinity` dimensions had cleared bounds, causing `isVisible()` to return false and preventing update/draw of children (e.g., HUD elements)
+- Sprite: fix `flicker()` not working with multi-camera setups — visibility was toggled per draw call (once per camera), so with 2 cameras the toggle canceled out. Now uses time-based flickering (~15 flashes/sec) that is frame-rate independent and multi-camera safe
 - Application: `Object.assign(defaultApplicationSettings, options)` mutated the shared defaults object in both `Application.init()` and `video.init()` — creating multiple Application instances would corrupt settings. Fixed with object spread.
 - Text/Light2d: fix invalid `pool.push` on CanvasRenderTarget instances that were never pool-registered (would throw on destroy)
 - CanvasRenderTarget: `destroy(renderer)` now properly cleans up WebGL GPU textures and cache entries (previously leaked in Light2d)

packages/melonjs/src/renderable/sprite.js

@@ -6,6 +6,9 @@ import { on } from "../system/event.ts";
 import { TextureAtlas } from "./../video/texture/atlas.js";
 import Renderable from "./renderable.js";
 
+// flicker interval in ms (~15 flashes per second)
+const FLICKER_INTERVAL_MS = 33;
+
 /**
  * additional import for TypeScript
  * @import {Vector2d} from "../math/vector2d.js";
@@ -141,7 +144,7 @@ export default class Sprite extends Renderable {
 			isFlickering: false,
 			duration: 0,
 			callback: null,
-			state: false,
+			elapsed: 0,
 		};
 
 		// set the proper image/texture to use
@@ -329,8 +332,10 @@ export default class Sprite extends Renderable {
 		if (this._flicker.duration <= 0) {
 			this._flicker.isFlickering = false;
 			this._flicker.callback = undefined;
-		} else if (!this._flicker.isFlickering) {
+			this._flicker.elapsed = 0;
+		} else {
 			this._flicker.callback = callback;
+			this._flicker.elapsed = 0;
 			this._flicker.isFlickering = true;
 		}
 		return this;
@@ -677,8 +682,8 @@ export default class Sprite extends Renderable {
 
 		//update the "flickering" state if necessary
 		if (this._flicker.isFlickering) {
-			this._flicker.duration -= dt;
-			if (this._flicker.duration < 0) {
+			this._flicker.elapsed += dt;
+			if (this._flicker.elapsed >= this._flicker.duration) {
 				if (typeof this._flicker.callback === "function") {
 					this._flicker.callback();
 				}
@@ -696,12 +701,12 @@ export default class Sprite extends Renderable {
 	 * @param {Camera2d} [viewport] - the viewport to (re)draw
 	 */
 	draw(renderer) {
-		// do nothing if we are flickering
-		if (this._flicker.isFlickering) {
-			this._flicker.state = !this._flicker.state;
-			if (!this._flicker.state) {
-				return;
-			}
+		// do nothing if we are flickering (time-based, frame-rate independent)
+		if (
+			this._flicker.isFlickering &&
+			Math.floor(this._flicker.elapsed / FLICKER_INTERVAL_MS) % 2 !== 0
+		) {
+			return;
 		}
 
 		// the frame to draw