Multiple masks do not work on the same layer

Symptoms

If one or more of these match what you are seeing, you are on the right page.

• •Applying a second mask removes the first
• •Only the most recent mask has any effect
• •Combining a clip path and an alpha mask gives an unexpected result
• •The masks work separately but not together

Causes and fixes

Ordered from most to least likely. Work down the list — each cause is paired with what to do about it.

1. 1

   Two masks are being applied to the same element.

   Group the already-masked element with Ctrl+G, then apply the second mask to the group. Each nesting level carries its own mask, and groups nest to any depth.

2. 2

   A clip path and an alpha mask are competing.

   They are separate mechanisms — a clip path restricts to an outline, an alpha mask varies transparency by alpha or luminance. Put one on the element and the other on a group wrapping it.

3. 3

   A single combined outline would be simpler.

   Use boolean operations to merge the two mask shapes into one path, then clip to the result. This is cheaper than nesting and avoids an extra offscreen buffer.

4. 4

   The nesting is costing performance.

   Each alpha mask and each isolated group requires its own offscreen framebuffer. On a VRAM-constrained device deep nesting causes slowdowns — prefer a single combined boolean path where the result is the same.

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