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Can someone explain why I get these thin lines?

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So I have recently just got affinity and so far it is great, I am having an issue though. I am using the isometric grid to create something but there is very thin white or black lines between the different shapes which I keep noticing, the shapes are right next to each other too so it isn't a gap. I am not sure if this is to do with my laptop or the software, does anyone know what this is? Sorry if it is obvious.





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Hi lewisosb,

Welcome to Affinity Forums :)

This is because there's something (an object) with a darker colour behind that's bleeding through the edges of the shapes due to the antialiasing.

Do you have any dark objects behind those shapes? Can you upload the file so we can check this out?


While this can be minimised on vertical and horizontal edges if the shapes are pixel aligned, it's difficult to avoid on diagonal/curved edges. In those cases, joining the shapes (Add boolean operation)  removes the thin lines between them. Alternatively adding a shape with the same colour behind them or adding a thin stroke (depending on the cases) may also help to hide them.

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I don't understand this on several levels. I don't understand your explanation MEB, on a technical level, as to why this occurs but more importantly I don't understand why it should occur at all. I don't mean to compare Designer to Illustrator but this doesn't happen with Illustrator. What is the difference in Designer that causes this? Why should vector objects need antialiasing? In an object produced by a mathematical equation, why isn't the edge of the shape, the edge of the shape? I realize that computer screens are pixel based. Are these lines an on screen anomaly? An annoyance that won't print? To clutter up a document with additional shapes to hide these unwanted lines doesn't seem like a very practical solution to me. Is this something that will be improved in the future?

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Hi jmac,

Regarding antialiasing, vector objects are defined mathematically but they still have to be rendered on a pixel screen. While vertical and horizontal edges can be aligned with the pixel grid to minimise the effect, diagonal or curved shapes pose a problem because you will get a stepped effect when you try to represent them using pixels (see screenshot - i've zoomed in to make the pixel grid easily visible). Antialiasing helps to smooth those steps adding semi-transparent pixels to help objects blend, however this also lets the background colours from other objects bleed through their edges (see attached screenshot - bottom right image).




Illustrator also have similar issues - see screenshot below - less or more visible depending the type of preview you are using: CPU preview gives better results than GPU preview - you can switch between them pressing  (cmd) + E). In the example below i created two objects - a rectangle and an ellipse - and performed a Divide operation, then placed a black rectangle below so you can see the issue more clearly.





You may also see hair thin lines which are related with the way Affinity renders the objects on screen/zoom level (different issue). If you check pixel aligned objects at 100%, 200% 400% and so on (x2), those hairlines will never appear. With arbitrary zoom levels this becomes a rendering issue (when the edges of two objects overlap). However in this case the file exports correctly, the lines only appear on screen. MattP is the most suited person to give you an explanation about why this happens and what can be done.

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