Creating gradient hatching?

Question

In QGIS, I want to color a polygon with a hatching in gradient mode. It should look like in the picture.

In this special case, it was realized with a green-to-yellow fill in the background, combined with a green hatching (line pattern fill) in the foreground.

But this is not possible when a gradient-hatching should be applied over different objects with different styles/colors. Any idea how this could be realized?

Here is the situation I want to use with gradient hatching:

The dark-blue hatching should be in gradient mode, but the background is in different colors like red, light-blue, white, another hatching in yellow etc. So the solution from the first example is not possible here. I want to have the dark-blue hatching with strong colors in the middle of the polygon, fading out towards the margins of the polygon-area.

Answer 1

To start, I don't think there is any functionality in QGIS to have lines drawn with gradients, and in particular gradients that fade out towards the edge of the polygon.

About the closest I think you will get is by creatively combining semitransparent layers.

On you blue hatched layer you can create a Line pattern fill on top of a Shapeburst fill. On the line pattern fill make the color your blue, but only about 25% opacity. On the Shapeburst fill make the first color completely transparent, and the second color something around 80% opacity, and move the Blur strength to the max value of 18.

This should give you the effect of a darker center that fades out towards the edges.

The example below shows a polygon layer of the US states colored as described above with some arbitrary red polygons underneath.