I would love to see something like that added to Krita, as well. I remember there was a person on the IRC some months back that modified the code to show an adjustable 3D axis assistant like that, even allowing for fisheye type distortion of the lines - but it was just a personal project of theirs and never attempted for it to get merged. I see no reasons to keep it in the current way.

When 'Snap to Assistants' option is off and Assistant tool is not selected, it's better for assistants to be automatically invisible on the canvas. Because a hexahedron automatically sets hypothetical vanishing points by itself anyway, in 100% accuracy. I'm not sure how the idea can be applied to krita, but for users who want to draw stuffs in perspectives, using editable hexahedrons (instead of setting up many vanishing points and parallel lines manually) could be very, very practical. I've been playing around with firealpaca(it's also a free painting application uses QT) and noticed it has a very interesting approach in 'snap' feature, which is an equivalent of assistant in krita.ġ Besides options mainly used for 2D shapes(parallel lines, grid, radial, circle, curve, etc), it has a mini 3d object simulator, and makes the simulated projection a 'layer'.Ģ If the layer is visible and the '3D Perspective Snap' option is on, the perspective snap feature takes effect.ģ You can select a specific object in the layer that you want to enable for snapping, with snap setting button.

How to use curve snap on firealpaca