Painting
Painting and vector drawing are two different layer models that sit side by side in the same scene, and the Brush, Pencil, Eraser and Fill tool all switch between them depending on what you have selected.
Celas Studio has two ways to hold painted or drawn content: pixel layers, where a stroke is a change to a bitmap, and Vector layers, where every stroke is still a Shape: a bezier path with points you can edit later. Which one you end up on depends on the layer you had selected when you started painting.
Pixel layers: Raster and Pixel
Two layer types hold pixels. A Raster layer is cell-based, the same "level" model as a Vector layer's drawings: each frame either holds its own painted cell or reuses the nearest earlier one, so redrawing a cell updates every frame that shares it. It defaults to 1920×1080, matching the canvas. A Pixel layer instead holds one continuous, borderless bitmap with no cells at all: its bounds simply grow to follow whatever you have painted on it.
Vector cells
A Vector layer is a cell container too, but each cell holds ordinary editable Shape layers rather than pixels, tagged to that cell. Painting or drawing on it with the Pencil adds a new Shape to the current cell instead of touching a bitmap: you get an editable path, not brushed-in pixels.
How a stroke is routed
| Tool | On a Vector layer | On a Raster or Pixel layer | On anything else / nothing selected |
|---|---|---|---|
| Brush | Unions the stroke into a shape's own vector geometry | Paints pixels | Paints pixels, creating a new Pixel layer on the first stroke |
| Pencil | Adds a new Shape to the current cell | Paints pixels (behaves like the Brush) | Creates a standalone Shape layer |
| Eraser | Not applicable | Erases pixels | Cuts a hole out of every closed Shape layer in the scene, if the layer itself is not a paintable Raster or Pixel layer |
The Fill tool follows the same idea: clicking a shape recolours it, clicking inside a Vector layer's drawing fills the enclosed area with a new shape, and only a Raster or Pixel target (or nothing at all) falls back to a plain pixel flood fill, creating a Raster layer if none exists yet.
What a stroke commits to
On a pixel layer, a single brush stroke builds up in a temporary buffer while you draw and is applied once, at the stroke's Opacity, when you release: so passing back over the same spot within one stroke cannot exceed that Opacity. On a Vector or Drawing layer, releasing the Brush unions the painted shape into the target's own geometry (or cuts it out, if the Eraser toggle is on), leaving one compound editable shape rather than a bitmap change.
Painting inside a selection
A live pixel selection masks painting on both models. A raster stroke and a vector blob are clipped the same way, live while you draw, so paint stops at the marching ants rather than spilling over and snapping back on release. Erasing is masked as well: a selection limits every paint operation, not only the ones that add.
The selection is made once, with the Marquee or the Magic Wand, and applies to whichever layer you paint on next: it belongs to the project rather than to a layer. See The Marquee tool for how to build, combine and soften one.
Alpha lock
Alpha lock freezes a layer's transparency and lets you repaint only its colour. Photoshop calls it Lock Transparent Pixels, Krita calls it Preserve Alpha. It is offered on Raster and Pixel layers, the two types that own pixels whose transparency there is anything to preserve.
Turn it on from the feature-button row at the top of the Layers panel, from the layer right-click menu, or from its own dot column in the Timeline. All three write the same flag, each is one undo step, and it is saved with the project. Toggling it from the right-click menu applies to the whole selection.
The rule is about the layer, never about the paint: an empty pixel stays empty and a half-covered one stays half-covered, and only the colour underneath may change. Painting over a lettering layer recolours the letters and leaves the space around them clear, however far outside them you stroke.
Everything that would change the layer's alpha is refused rather than half-applied while the lock is on. The eraser and Delete leave the pixels alone, the fill bucket recolours what is already there instead of spreading into empty space, and a marquee drag does not lift a floating selection, because lifting cuts the pixels out.
Painting and drawing side by side
Because both models are just layers, you can stack them freely: a hand-painted pixel background under a rigged vector character, or vector clean-up over a rough pixel sketch. Painted content in a Raster or Vector layer is managed cell by cell in the Cells panel; a Pixel layer has no cells to manage, since it is always just the one continuous image.