Brush masking

Paint a mask for each projector with the brush, and shape it with the size, hardness and opacity controls.

A mask holds back parts of a projector's image: spill past the edge of a set piece, a doorway you mustn't light, or a strip where two projectors overlap and one of them needs to give way. Every projector has its own mask, painted at that projector's resolution and saved with the project.

For overlaps, you don't need to paint the fade yourself. Moonblend calculates it from the scene, on a layer of its own.

The mask moves with the warp

You paint the mask on the projector's picture, not on the wall. Moonshine applies the mask before it warps the picture, so if you correct the warp later, the mask moves with the picture. Your paint reaches the projector's output (a display, NDI or SDI) about a second and a half after you stop painting.

Open the mask editor

1. Click Mask in the top bar, or press / to open the command palette and run Go to Mask.
2. Check the toolbar at the top of the paint area. It shows the projector's color, Editing mask for and the projector's name.
3. To work on a different projector, choose it from the projector menu in the top bar, or press 1 to 9 to select one by its position in the list.

Switching projectors saves the mask you were editing and loads the next one, so you can work through a rig one projector after another.

You can also open the editor from the scene graph. Every projector has a Mask node under it, and clicking it selects the projector and opens this tab.

You are looking through the projector's warp

The paint area shows the projector's picture bent by its warp, as it lands on the wall. The dashed rectangle marks where the unwarped picture would sit. Painted areas go black on the projector. An unpainted mask changes nothing, and the softer the brush edge, the more gradually the light falls off.

With Video off (in the toolbar, before the zoom buttons), the picture is flat gray. Switch it on to paint against what the projector is playing, and use the arrow beside it to dim the picture. It starts at 50%. Video is the same switch as on the Warp tab, but the Mask tab keeps its own dimming setting.

Move around the paint area

Action	Result
Scroll wheel	Zoom, from 25% to 800%, centered on the pointer
Right-button drag, anywhere	Pan
Middle-button drag	Zoom in (drag right or down) or out, around the point you pressed
Buttons at the end of the toolbar	Zoom out, zoom in, and Fit back to 100%, centered

Zoom works the same as on the Warp tab and the Outputs canvas. Panning is different: here a left drag paints, anywhere in the paint area including around the picture, so pan with the right button instead. The zoom level shows in the bottom-right corner of the paint area.

Zooming doesn't change the brush. Brush size is measured in the projector's pixels, so the ring under the pointer grows and shrinks with the zoom to show what you'll paint.

Paint and erase

With Tool set to Brush, drag on the paint area to add to the mask. Switch Color to Erase and drag to remove it. Press X to switch between the two without leaving the paint area. A quick way to work is to paint the rough shape, then erase back into it.

Tool and Color are at the top of the Properties sidebar. If the sidebar is hidden, press \ to show it.

The brush controls

All the brush settings are in the Properties sidebar, and each has a shortcut that works while you paint.

Control	What it does	Range	Shortcut
Tool	Brush painting, or pen path editing	Brush / Pen	B / P
Color	Whether the brush adds coverage or removes it	Paint / Erase	X toggles
Shown as, in the Paint heading	The color paint shows in on this tab. It affects the screen only: painted areas are always black on the projectors	Any color; black to start
Brush Size	Brush diameter, in the projector's pixels	1 – 1000	[ / ] in steps of 5; { / } in steps of 1
Hardness	How sharply the brush edge falls off	0 – 100%	, softer / . harder, in steps of 10%
Opacity	How much coverage one stroke adds	0 – 100%	- / = in steps of 10%

A new user starts with Brush and Paint selected, at size 40, 50% hardness and 100% opacity, with paint shown in black. Moonshine remembers your changes between sessions.

Hardness sets how abruptly coverage stops at the edge of the brush. At 100%, the brush is a solid disc with a crisp edge, for cutting along a hard line such as a door frame, a screen edge or the corner of a set piece. At 0%, coverage fades from the center of the brush all the way to its edge, for an edge that should fade out. Values in between narrow or widen the fade.

Past the edge. The brush paints anywhere in the paint area, including the space around the picture. Hold a soft brush slightly outside the picture's edge and only the faint outer part of the brush reaches the picture, giving the gentlest falloff along that edge.

Opacity below 100% lets you build coverage gradually. At 20–30%, each pass darkens the area a little more. Use this to build a gradient across a strip instead of a hard boundary.

One drag is one pass

Coverage doesn't build up within a single drag. Scrubbing back and forth over the same spot without releasing gives the same result as one pass. To build up coverage, release and drag again. This keeps low-opacity work predictable.

Straight lines

Hold Shift and click to paint a straight line from the end of your last stroke to the point you click. Keep clicking to follow a straight edge across the frame, such as an architectural line where a freehand drag would wobble. The line uses the current size, hardness, opacity and paint/erase setting.

After you open the editor or switch projectors, paint one ordinary stroke first. The first shift-click has no previous point to start from.

Painting with a stylus

With a pen on a tablet, pressure scales the brush. Light pressure paints narrower than Brush Size, and full pressure paints at the size you set. A mouse or a finger always paints at full size.

Keeping paint inside a shape

For a clean edge, draw a closed shape with the pen tool and leave it selected. Brush strokes then land only inside the shape, even if you drag across its boundary. See Vector masks.

Undo

Ctrl+Z steps back through your painting, up to 50 strokes. A large mask keeps fewer, because each step stores a copy of the whole frame: about 30 at 1920 × 1080, and 8 at 3840 × 2160.

Undo in the mask editor follows the order you worked in, whichever tool is selected. Brush strokes, path edits and Moonblend Uniformity changes share one history, and Ctrl+Shift+Z redoes what you undid. Loading a mask clears the painting from the history. Layers and undo covers what undo can and can't recover.

Start over

The Properties sidebar has three resets. Each one asks first and says what it will clear. Choose Cancel to back out or Reset to go ahead.

• Reset Paint, at the bottom of the Paint section, clears every brush stroke and vector path on the selected projector. You can't undo it.
• Reset Moonblend, in the Moonblend section, clears the blend on every projector, not only the selected one. Calculate makes it again.
• Reset All, below both sections, does both.

Paint belongs to each projector, so resetting one projector's paint leaves the others' alone. While Follow masks is on, Moonblend keeps blending around the paint that remains.

Saving, and working alongside other operators

There's no save step. Your work is saved to the show machine a moment after you stop painting, and again when you switch to another projector.

Opening the Mask tab takes the lock on that projector's mask, so nobody else can paint on it. Anyone else who opens the same projector's mask sees a padlock badge with your initial at the top right of the paint area. Hovering it shows your name and is editing. Request access, and clicking it asks you to hand the mask over. Until you do, or release it, their controls stay dimmed and their pointer doesn't paint. They can still use the zoom buttons to look closer. See Locks.

The lock stays with the projector, not the tab, so moving to another tab keeps it. To release it, select a different projector or click the padlock button at the top right of the paint area.

Where to go next

• Vector masks: the pen tool, for precise shapes, curves, and stencils for the brush.
• Layers and undo: how painted coverage and paths combine, and the limits of mask undo.
• Projectors: a projector's resolution sets the size of its mask.
• Keyboard shortcuts: the full list, also available in the app from the ? menu.