Background Mask

backgroundMask lets particles punch through or blend with a masked background layer.

Examples

Static cover (legacy)

backgroundMask: {
  enable: true,
  cover: {
    color: {
      value: "#0b1020",
    },
    opacity: 1,
  },
}

Dynamic draw callback (since 4.3.0)

backgroundMask: {
  enable: true,
  cover: {
    draw: (ctx) => {
      const t = performance.now() * 0.001;
      ctx.fillStyle = `hsl(${(t * 30) % 360}, 70%, 50%)`;
      ctx.fillRect(0, 0, ctx.canvas.width, ctx.canvas.height);
    },
  },
}

External element (since 4.3.0)

backgroundMask: {
  enable: true,
  cover: {
    element: "#myVideo",
    opacity: 0.8,
  },
}

Properties

Property	Type	Description
enable	boolean	Activates background masking
composite	GlobalCompositeOperation	Canvas composite operation (default: "destination-out")
cover	BackgroundMaskCover	Cover configuration

cover (BackgroundMaskCover)

Property	Type	Description
color	string / OptionsColor	Cover color
image	string	Cover image URL
opacity	number	Cover alpha level (0..1, default: 1)
element	string / HTMLCanvasElement / OffscreenCanvas / HTMLVideoElement / HTMLImageElement	External element or CSS selector auto-drawn each frame (since 4.3.0)
draw	(context: BackgroundDrawContext, delta: IDelta) => void	Custom draw callback on main canvas context each frame (since 4.3.0)

Layer order (since 4.3.0)

1. clear() — canvas pixel clear
2. cover.element auto-draw (if set)
3. cover.draw callback (if set)
4. Static cover (color/image) — fallback
5. Global composite operation

When to use it

• Spotlight-like effects.
• Contrast-heavy hero sections.
• Layered interactions on dark backgrounds.

Source reference

• https://github.com/tsparticles/tsparticles/blob/main/markdown/Options/BackgroundMask.md