Mouse, pen and trackpad

Every click, drag, wheel tick and modifier, on the canvas, in the panels, and what a graphics tablet adds.

Celas Studio expects a three-button mouse with a wheel, and gets more out of a pen: pressure, tilt and barrel rotation all feed the brush engine. The modifiers below are fixed and follow common desktop conventions. The one thing you can tune is how the pen's pressure is read, in Preferences ▸ Pen.

Left button draws, selects and drags. Right button opens context menus. Middle button pans, wherever you are on the canvas.

Moving around the canvas#

A wheel tick is ignored while you are mid-drag on artwork, so a nudge of the wheel cannot zoom out from under a move. Pan and zoom are both switched off in Camera View and in the 3D view. Ctrl+0 fits the canvas again and clears any view rotation.

Selecting and transforming#

Drawing and node editing#

Pixel selections and painting#

Alt with the left button is a temporary eyedropper in almost every tool: it samples the colour under the cursor and hands it to the fill. Hold Shift as well and it goes to the stroke instead. The exceptions are the Node, Pen and Bone tools, and the Weight Paint tool in paint mode, where Alt already means something else. Brush and Smudge strokes will not start while Ctrl or Alt is down, for the same reason.

Panels#

What a pen adds#

A tablet gives you extra streams, and they are recorded along the stroke:

• Pressure, from 0 to 1, drives brush size and opacity through the dynamics in Brush Studio, and the width of a vector Pencil line. It is read for every sample the pen reports, not once per screen frame, so it changes smoothly and a pen lift tapers naturally.
• Tilt is how far the pen leans, whichever way it leans. Most brushes use it: a round brush opens onto its side, and pencils, charcoal, chalk and crayon shade with the side of the lead.
• Barrel rotation is how far you roll the pen in your fingers. Only pens with a rotating barrel report it. A brush uses it when a row on the Dynamics tab of Brush Studio has Barrel rotation as its source: on the Rotation row, the tip turns as you roll the pen.

The path of a stroke comes from every position the system reports, so fast strokes keep their curve instead of turning into straight facets, and a single stray sample never becomes a spike.

Calibrating the pen#

Pens and hands differ: on one pen your firmest press may never reach full pressure, and on another a light touch may already give too much. Preferences ▸ Pen fixes both for every tool at once. Draw a few strokes on its pad and click Calibrate, and your own firmest press counts as full pressure. The Pressure curve beside it makes the pen feel softer or firmer, and a graph shows your pen live as you press. See Preferences.

A mouse reports no pressure, so the brush draws its own taper instead of thick-and-thin. That is by design: it keeps a mouse usable rather than making it draw hairlines. Pen Pressure on the Brush bar switches the pen to the same behaviour when you want it.

On a touch screen with a pen, Pencil draws, finger navigates in Preferences keeps the two apart: the pen marks the canvas and a finger pans and zooms. It is on by default.

Input is read straight from the tablet driver: Wintab on Windows, with the Windows Pointer API as the fallback when Windows Ink is switched on in the driver; NSEvent on macOS; XInput2 on Linux, including Wayland through XWayland.