Affinity Photo Filters and Distort and Shear menu command. Drag the curve for vertical displacement. Drag the curve for horizontal and apply. It comes with a few options such as horizontal and vertical. The effect is a destructive effect, sadly there is no live filter layer counterpart
If you apply it as a single layer image and then apply the effect then the result will leave gaps or transparency in the image. You may wish to add a background such as black and the original image.
You can also apply it once or multiple times either going to the menu command or use the repeat feature. You can use this warp the image in countless ways.
The effect can be used with selections, create a selection using rectangular marquee tool or the freehand tool etc, any effects applied will be just warps to that region. You can shift or re-size etc the selection and then re-apply the effect. You can also create a mask and use the effect to distort that and then use the distorted marching ants with your image
You get the vertical / horizontal box. You can get a vertical line and horizontal line and by default, nothing. Select the top or bottom of point to shift it right to left or up and down with any warping. You can, however, add additional points beyond the first two but sadly only to the line itself. I don't know if there is a limit to the number of control points you can add, you can't re-size the panel nor can you modify the strength of the effect beyond having the point as close as possible to the default start position. You can only add control points where the line is away from the edge of the boxes. You can drag the points and re-position them. It is possible to click the line and no point is added and then move one of the other points slightly and then you can add a new control point (there appears to be little logic to why or why not a point can be added)
You can also use the shear filter over different channels via the channels panel such as select the red channel and apply it there and select the green channel and apply it there, different or the same. You can repeat it multiple times as well as combine with the fade and blending modes etc to create all kinds of color combinations. If you are using the channels then it is always useful to have the navigator panel open and as big as possible as you can see the result of the effect on the overall RGB image which cannot be seen as you work with the preview.
You can use different distorts on different layers. You can also use the effect with linked layers (via the duplicate linked command). You will be able to see the transparency of the document or any background images as you modify the control points of the vertical and horizontal.
You can record the steps and combine the warping effects with other filters and use in macros panel
You can use it to modify a pattern layer or the active part of the pattern layer
The effect can be faded via the edit menu and fade command and you can blend in a difference or lighten etc as well as change the opacity of the effect