The Mask node uses the geometry of one set of shapes to control the visibility of another. It can also apply blend modes and opacity, making it a powerful tool for both clipping and advanced compositing.
Inputs
The Mask node has three inputs. The order is important for achieving the desired effect.
Input
Background
Mask by
Parameters
| Parameter | Description |
|---|---|
Label | The display name for the node. |
Mode | Specifies the global compositing operation. |
Opacity | Controls the opacity of the Input layer. |
Swap Inputs | Swaps the Input and Background inputs. Useful for non-commutative blend modes. |
Invert Mask | Inverts the mask, effectively punching a hole in the Input. |
Masking Explained
By default, a mask defines where the content is visible, not where it’s cut out. The Mask by input works as a vector clipping mask that affects the Input stream.
Think of it like a “window” or a “stencil.” The outline of the shape(s) connected to the Mask by input defines the area where the Input shapes are allowed to be visible. The color, stroke, and opacity of the masking shape are completely ignored—only its geometry matters. This means the effect is all-or-nothing; a part of the input is either 100% visible (if it’s inside the mask) or 100% invisible (if it’s outside).
Inverting the Mask
To achieve a “knockout” or “punch-through” effect, you can enable the Invert Mask parameter. When enabled, this flips the mask’s behavior. Instead of a window, the masking shape becomes a “punch” that cuts a hole in the Input shapes, revealing the Background or whatever is underneath.
Compositing with Masks
In addition to masking, this node can also apply blend modes and opacity to the Input stream before it is composited over the Background. This allows you to create complex layered effects within a single node.
For example, you can use a Mask by shape to clip a noisy texture, and then use the Mode parameter to blend that masked texture onto a background shape using Overlay.