I am applying Kawase blur to several layers. On one layer, on the bottom and right edges of the screen, an unwanted light border is introduced. This is despite the artwork not being cropped to the scene i.e. some of the artwork ‘spills off’ the edges. In photoshop, if you blur an image that is the same size as the canvas, you get a border like this, where you can see the white or transparent background behind the photo because there is not enough image beyond the canvas edge for the blur to be effective. The light border that GDevelop adds does not seem to be the scene colour (I changed it to see) and it is not the colour of the artwork underneath the layer in question.
Gaussian blur does the same thing.
This issue does not affect most of my other layers - only this grass layer and one other (the other is also at the bottom edge of the scene). The issue happens with tiles and regular sprite objects. There are no other effects applied to these layers. The Kawase blur’s padding setting doesn’t make any difference, though I am unsure what it’s supposed to do in the context of this effect.
If the effect behaved the same way on all edges with all my layers, I would put it down to “That’s just how the effect is”, but it only affects 2 layers in my project.
Game preview. The tiled sprite at the bottom of the screen gets a light border on the bottom and right edge.
And here’s how the grass tile looks in the scene editor.
Game preview without blur (my grass graphic has some blur on it within the image, so that’s why it already looks somewhat blurry. That is not an effect applied in GD; it is baked into the image).
Game preview with the blur turned on (when my protagonist opens his quest book).
And with the affected layers hidden. The main artwork is fine with blur on and has no unwanted edge.
Edit: another example from another scene, where the issue is more obvious:
Before blur turned on.
With Kawase blur turned on. Notice the bottom of the bin/trash bag. Again, there is around 20 pixels of bag graphic that falls below the scene edge.
As an experiment, I tried removing the blur from the sprite object (the blur applied to the graphic itself in the art software) and this made no difference. I tried with solid objects (no transparent pixels). No difference. Both blur effects introduce an unwanted border on the bottom and right edges of the scene for my foreground layers.