Recently, I tried to create a vector brush based on a vector shape in Affinity Designer. I was surprised to find that there are really two types of vector brushes. Let's take a look at an example.
One type of vector brush is based on a vector shape or image. Because the base image used to create the brush is vector, the brush stroke remains in the vector format, containing many vector paths and anchor points (nodes). The other type of brush is based on a raster image. This "vector" brush takes the raster image and stretches or repeats the image along the vector path created by the vector brush, resulting in only a few anchor points along that single vector path (see screenshot).
Of course, the second type of brush defeats the purpose of using vector brushes, as the raster image cannot be scaled without loosing image quality. Unfortunately at this time, this is the only type of "vector" brush that you can create in Affinity Designer. Although, there are many customer requests in the forum for the addition of vector based brushes. So, maybe in the future Serif will add this feature.
If you still want to use brush strokes created in Designer in a vector format, you can manually reproduce the stroke's raster texture by drawing with the Pen tool (see screenshot). I've tried this a few times on small projects. Although it was time-consuming, it did result in some interesting vector shapes, which I saved in the Assets panel.
If you don't have the time or desire to reproduce the stroke texture with the Pen tool, you will need to vectorize the brush stroke in another vector program, which has an image trace feature. After you apply the image trace to your stroke, the raster texture will be converted in to vectors. This is how I converted the example brush stroke in Illustrator (see screenshot). It's much easier if you isolate the brush stroke on a new layer.
There are several vector apps that have an image trace feature, including Vectornator's Auto Trace. The Auto Trace has only two slider controls for customizing the number of paths and the minimum size for the paths. For fine adjustments, there is also controls for adding and removing anchor points.
Another option is to use the Trace Bitmap feature in Inkscape. This feature has three filters for customizing the trace, which are the Brightness Cutoff, Edge Detection and Color Quantization. To make finer adjustments, you can use the Simplify Path feature.
There is another option for vectorizing your brush strokes. There are many online programs that can do the job. However, they vary in the results and how much it will cost to use the service.
Affinity Designer Brushes
Affinity Designer has two brushes, one for each Persona (workspace). In the Designer (vector draw) Persona, you have the Vector Brush Tool (see screenshot). This is the brush we were talking about above. When you switch to the Pixel Persona in Affinity Designer, you will have a raster Paint Brush Tool (see screenshot), instead of the vector brush. You can tell the difference as the brush stroke is on a Pixel layer, which you are told by the alert message. Also there is no vector path or anchor points.Inkscape Tutorial: Tracing Bitmaps
https://inkscape.org/doc/tutorials/tracing/tutorial-tracing.html
Vectornator Auto Trace
https://www.vectornator.io/learn/images
Screenshots used by permission of Serif (Europe) Ltd. This article is not endorsed by Serif Ltd.
