v4.2.1 WebGL: sprite batch corruption when an angle tween runs on a GameObject whose position is also written every frame

[chsami]

Version

• Phaser 4.2.1 ("Giedi"), WebGL renderer (type: AUTO)
• Observed on Linux, Chromium 149 (Playwright headless shell) — also reproduced through several independent scene setups in the same environment. Not yet verified in headed browsers.

Description

When a GameObject has a continuous angle tween running while its position is written imperatively every frame (in scene.update()), sprites in the scene render with corrupted geometry: wedge-shaped chunks missing, or the quad drawn as displaced slices — it looks like one vertex/triangle of the sprite's quad (or its UVs) is wrong for a frame.

Either behavior alone renders perfectly. The combination corrupts.

Reproduction matrix (all with 152×136 PNG textures)

angle	position	result
static (0° or any fixed angle)	written every frame in update()	✅ renders fine
tweened (yoyo/repeat: -1)	static	✅ renders fine
tweened	written every frame	❌ corrupted (wedges/slices)

The corruption also reproduces when the moving object is a Container and the angle tween targets a child Image (container position written per frame, child angle tweened).

Minimal repro sketch

class Repro extends Phaser.Scene {
    create() {
        this.img = this.add.image(400, 300, 'anyTexture');
        this.tweens.add({
            targets: this.img,
            angle: { from: -4, to: 4 },
            duration: 1500,
            yoyo: true,
            repeat: -1,
        });
    }
    update(time, delta) {
        this.img.x += 20 * (delta / 1000);   // any imperative per-frame movement
        if (this.img.x > 900) this.img.x = 100;
    }
}

With the tween removed (or replaced by a scale/y tween), rendering is clean. With movement removed, rendering is clean.

Workaround

Express "float/wobble" effects on moving objects with scale or child-y tweens instead of angle tweens, or keep rotation static while moving. That fully avoids the artifacts.

Happy to provide screenshots of the corrupted frames or a fuller runnable repro if useful.