---
title: "Masks and mattes"
description: "Lesson 7.3 of Creator Terminal's lesson films (Going deeper): Reveal a circle through another layer, then draw a mask on the circle itself."
canonical: "https://terminal.lottiefiles.com/masks-mattes/"
last_updated: 2026-10-27
---

# Masks and mattes

> Lesson 7.3 of Creator Terminal's lesson films (Going deeper): Reveal a circle through another layer, then draw a mask on the circle itself.

- The film (1:40): https://terminal.lottiefiles.com/media/7.3-masks-mattes/319f94c23b17/7.3-masks-mattes.mp4
- Vertical cut: https://terminal.lottiefiles.com/media/7.3-masks-mattes/c808bcc8add8/7.3-masks-mattes-vertical.mp4
- Captions: https://terminal.lottiefiles.com/media/7.3-masks-mattes/c91bfffb637e/7.3-masks-mattes.vtt
- The page: https://terminal.lottiefiles.com/masks-mattes/

## In this lesson

### Just covering (0:09)

We want to reveal the coral circle through a window. The green rectangle only covers it. Click the exposed coral edge to select the circle.

### Choose a source (0:20)

We'll use another layer to decide where the circle shows. That's a matte. Click the Matte control. In the list, press down for Window, then return. Another layer now makes our opening.

### Colour stays coral (0:33)

The rail says alpha. That means opacity controls the opening. Look at the stage. The green has gone, and the revealed colour is still coral.

### Keep one layer (0:44)

Now we'll draw the opening on the circle itself. Press U to undo. Click empty stage, then the green rectangle. In the rail, click delete. Back on stage, click the circle.

### Draw a mask (0:58)

Let's draw that opening. Press Control-M, then Shift-R. Drag a rectangle inside the circle. Press Escape, then Control-M again to leave mask drawing. This mask belongs to the circle. Only the inside shows.

### Reverse the opening (1:15)

Let's reveal the outside instead. In Masks, click inv to invert it. Look at the opening. The inside is hidden now. We've changed visibility, without cutting away the circle's drawing.