The Affinity Photo Affine Filter can be found in the distort sub menu of distort. It is close to the bottom but it should not be over looked. It is a powerful tool that can be combined with other tools in the application as well as combined with macros and channels as well as layers and used with shapes and type and much more.
The powerful effect can be used once or multiple times to create amazing transforms of all kinds of images and type as well as resources as brushes etc. Go to the effect and set the rotation, scale X setting, scale Y setting, offset X, offset Y, extend mode (wrap, mirror etc) and click apply.
The key thing about the tool is that is for transformations such as scaling and offset and rotation along with extend mode. There a number of options such as "scale X" and "scale Y" and "offset X" "Offset Y" and "extend mode". The extend mode works in the same way as other tools, that it offers zero (generates result with transparency) and full (background) and repeat (single item) and wrap (actually repeats) and mirror (repeats but mirror). OK, once you have that with the effect then you can take any image and scale the current artwork in the horizontal or vertical via scale and shift or offset and rotate the art. This tool has sort of been superseded by the equations panel but equations requires a little bit of maths skills, this panel requires none other than to set the rotation, scale etc. You can enter the values via the sliders as well as into the edit fields.
You can leave the scale at 100% for the x (horizontal) and y (vertical) but you can also enter 25% for one and 150% for the other as well as change the rotation angle so the artwork can be angled to create an intense shear effect. You can also change the rotation angle but by default it will constrain to certain settings such as 90 degrees etc but you can also click into the field and enter an override value or hold the shift key down.
You can go to the entries in the panel and instead of typing 75% or 100% etc, you can also enter 2*25% etc or if you want 1/4 of the size then you can go and enter 100/4 and it will calculate the value for you. Or you can enter 25+50 into the offset field so you can move a design by 50px etc just by entering the maths for it.
Zero means you end up with potential transparency, with full you will get the same but a white background. Repeat creates a stretch effect from the edge. Wrap repeats but with seams and mirror repeats but flips the design and creates a lovely seamless artwork.
You can use the artwork as a background layer but if you can also use the artwork as a layer and use that with it. If you use the tool with a layer then the zero extend mode is more useful as you can then see the lower layers. If you use the other modes such as wrap then the layers can also be useful as the tool can be used perhaps to create multiple repeat copies (set the scale x and scale y to 20% say) and then you can then use the blending modes for the layer via the layer panel so a difference blending mode or lighten blending mode can be added to the layer (or perhaps opacity) and you can then combine the effect along with the original image.
You don't have to use the original image and the effect, you can also use it with a layer made of a shape (such as a star) as well as type or perhaps a placed image and that can also be duplicated and scaled and rotated etc on top of other images or layers. You can just create a star from the toolbar and then run the effect and set the scale to 20% etc and you will generate a number of copies of that vector design. The same can be done with type and the effect to create truly amazing wonderful text designs in seconds.
You can use the effect with other tools in the application but you can also use it multiple times with different settings, just go back to the filters menu and distort and re-apply and set the angle and scale and offset to different values than the first application. So, first apply, set the rotation angle to 45 and scale to 20% and then re-apply it but set the angle to 315 and scale to 50%. All kinds of weird transformations can be added to any image by combining them. All kinds of unique combos can be created in that way
Macros, a recent addition, which involves two panels, macro and library and they can be found via the studio command. OK, bring up the macro panel and then click the record command (at the top of the panel) and then apply it with different settings or perhaps combine with others such as Gaussian blur etc) and then click the stop recording. You can also then click the add to library (top of macro panel) and save it to the application for future use. You can modify the settings via the little gear beside each of the commands recorded or just remove it. Click the run button at the top of the panel. Or go to the library panel and click the macro or use one of the others. Macros are excellent as a simple combination of deform and the transformation effect can be used to create 100s of unique seamless patterns in seconds which can be re-applied with any image.
Sadly, there is no live entry for this effect (why ??) though the best way around this is just to use the source layer and then add a duplicate and then use the blending modes and opacity found in the layers panel and you can then combine effects in countless ways by using the powerful features of the layers panel and the great thing about that is that you can group items and remove items and add and paste inside and multiple other options, many of these features are unique to the program
You can use the powerful scaling and transformation effect with color channels, just display the channel panel and click the red channel etc and apply the scaling and transformation effect there for that and use different settings for each channel. You can use that to create some interesting colorful effects. You can find the channel panel in the view menu and studio commands
You can use the transform command with the pattern layer (you can now quickly create a pattern layer from a selection via the layer menu) and you can add the transformations before the that or after you have created the layer. Great for creating all kinds of kaleidoscope effects
Create a layer and add a linear gradient to it via the tool (hold down the shift so you get it straight from top to bottom.). Apply vertical scaling of 10% and wrap extend mode. Sadly, it can only work with 10% as the minimum, though a workaround is to apply it two or three more times via the repeat feature but it would be good if you could enter 0.01% etc and create even more amazing lines from the design. This can be used with any colorful preset. If you apply the design at 45 degrees, the result will be different but in that can you may prefer the mirror extend mode instead. The mirror mode gives more an effects line kind of result such as seen in manga work. That is used with black to white but of course there are limitless presets available so all kinds of super colorful designs can be created just by using at 10% vertical or perhaps using 25% vertical and repeat which you may find more controllable
You can use the panel and change the scale and rotation but one great feature about the application is that is non modal so you can also use layers, apply duplicates, change layers, change blending modes as you work with the panel open so you can make minor adjustments to your work with the effect still in progress. You always have to remember to click apply otherwise if you go and try and run another, you don't get both running at the same time (though that would be interesting). You can run through all the blend modes for all the layers such as hard mix, difference, exclusion etc and create some truly wonderful combinations of designs.
You can use a gradient as a great source for a sea wave design. Create intense gradient designs by using the effect with a slightly angled design to create a more effect lines design and then use the deform tool to warp the wave along the top of the layer. I would suggest re-sizing the layer so the layer is not close to the top of the image otherwise the wave will be cut off and it will look odd. You can then duplicate the layer by holding down the alt / option key and then repeat the waves by using different handles to the deform and distorting it in different ways. It is a layer so you can also go to the layers panel and clicking the fx button and adding layer effects such as outer shadows. You can re-position the wave designs. You can create multiple layers of curved designs. You can also go to the layer menu and select the threshold adjustment layer and apply a threshold and you can change the threshold setting. Once you are happy with everything you can go to the layer menu and merge visible.