Paint brush does not follow Isometric grid when shift held and jumps position

[ziplock9000]

When I hold shift and draw using the paint brush tool when I have an isometric grid selected it only constricts the movement to horizontal or vertical axis, and not along the grid as expected.

Another related issue is that when clicking on another part of the screen causes the pen to draw a line from the last place drawn when shift is held, even though the mouse button was released when it was moved.

data.mkv

[MEB]

Hi @ziplock9000,
Welcome to Affinity Forums
Sorry the delay getting back to you.
1. The snapping only works with vector based tools (by design). Try for example using the Pen Tool with snap to grid enabled in the Snapping Manager. The Paint Brush Tool is a raster based tool and doesn't snap/follow the grid or guides.

2. The Shift key modifier has two functions:
- help to draw a straight brush stroke;
- constrain the movement of the tool to the horizontal and vertical axis.

To draw a straight stroke: press and hold the left mouse button to start painting a stroke as usual, when you reach the point where you want to force a straight line press and hold shift and then release the mouse button; click and drag a little bit with the mouse button where you want the straight line to end (while still holding the mouse button), then release the shift key and continue dragging/painting with the mouse. It's easier to do than it is to describe in words.

To constrain the movement to horizontal/vertical axis: while dragging the mouse to paint a stroke (the mouse button is always pressed during the whole process) press and hold shift when you want to start constraining the movement to one of the axis, then release the shift key when don't want to keep constraining the movement anymore, all while you continue dragging the mouse to paint the stroke.

For more details about how the Paint Brush Tool works along with more modifier keys please check this Help topic: Painting brush strokes