Painting guides, rulers and perspective in Paint by Zaweba
Paint by Zaweba's Painting Guides tool snaps strokes to rulers, ellipses, perspective grids, fisheye and spline guides, and Shift breaks free.

Drawing a convincing street, a row of wheels or a room seen from inside takes structure, and freehand lines rarely supply it. Painting guides give your brush something to run along, much like a set square or an ellipse template on a drawing board, while you keep using your ordinary brushes and their pressure.
The Painting Guides tool in Paint by Zaweba places the guides, and from then on strokes snap to the nearest guide shape or to the family you've chosen. Hold Shift and the stroke breaks free, so you can mix guided and loose work without switching tools.
The guide shapes
Ruler gives a straight line between two points. The infinite ruler extends that line across the whole canvas, and the parallel ruler makes every stroke run parallel to it wherever you start, which is ideal for hatching, wood grain or rain.
Ellipse snaps to one ellipse you set. Concentric ellipse makes every stroke an ellipse sharing that centre and shape, so you can draw a set of rings, a plate with a rim or the layers of a tree trunk.
The perspective guides cover 1, 2 and 3-point perspective. Set the vanishing points and your strokes follow lines towards them. There is also a separate vanishing point guide for a single convergence point you want to add to a scene.
Fisheye bends lines along the curved grid of a wide-angle lens, for dramatic close-ups of characters or rooms. Spline lets you draw a smooth curve of your own and then trace along it as often as you like, which is handy for a recurring road edge, a ribbon or the sweep of a car body.
Snapping and breaking free
Strokes snap to the nearest guide or to the family you have picked. With a two-point perspective set up, for example, a stroke goes to whichever vanishing point fits the direction you started in, so you can draw left-going and right-going edges one after the other without changing anything.
Holding Shift breaks free of the guides for that stroke. Use it for organic shapes in a perspective scene: trees, people, cloth. Let go and the next stroke snaps again.
Setting up a scene
Lay out the horizon first. In perspective, the vanishing points sit on the horizon line, and getting that height right decides whether the viewer looks down on the scene, across it, or up at it. Then place the vanishing points. Points set wide apart, even outside the canvas, give a calm, natural view; points close together give a strong, distorted one.
Block in the big shapes with the guides on. Boxes for buildings, ellipses for wheels and round objects, parallel lines for floor tiles. Once the structure is right, sketch the details on a new layer with a looser hand, using Shift whenever the guide gets in the way.
Keep a separate layer for guided construction lines and lower its opacity once you are inking. That way you can still see the structure without it showing in the finished picture.
Saved with your work, never in the export
Guides are saved in the .ptx document, so when you reopen a scene days later the perspective is still set up exactly as you left it. They are never exported. A PNG or JPEG of your painting contains only the paint, with no guides drawn on top, so there is nothing to hide or delete before you share it.
Using guides with other tools
Guides control where a stroke goes, while the stroke stabiliser controls how smooth it is. For inking a perspective scene, a little stabilisation combined with the guides gives clean, confident lines. Wrap-around mode is a different kind of helper, for tiling textures. Between them, these tools in Paint by Zaweba take the measuring and fiddly construction off your hands so you can spend your time on the drawing itself.
A quick test is worth doing before a big piece: set up a two-point perspective, draw a few boxes, and get a feel for how the snapping chooses between directions. Ten minutes of play is enough to make the tool feel natural.