display rendering artifacts

[AndyQ]

Something which is irking me endlessly in Designer: the visible faint outlines of objects that should be obscured, both in the on-screen display and on PDF output. The attached example shows a blue square behind a white square. The white square is a copy/paste version of the blue. It's the of same dimensions and coordinates and should completely obscure he blue square, but a faint outline still appears; like the perimeter of an antialiased line.  In this particular case export to PDF shows nothing - the white square does obscure the blue square completely, but in other cases, where there are angled lines or curves, the artifacts show through. I'm having to do extra work to trim objects that should be "behind" others and non-visible in areas with a common border. I do have reasons for this, so please don't point out that I should simply get rid of the "object behind" or otherwise move common borders inwards. Cheers!

[Lee D]

This is due to antialiasing, a darker object being inserted behind a lighter one and it's bleeding through the edges. It can be kept to a minimum if you pixel align the objects but it will be more noticeable on objects with a curved or diagonal edge. This should only occur on screen, exporting should be fine.

A workaround can be to add a small stroke to the darker object and set it's colour to the same as the lighter one.

[AndyQ]

16 hours ago, Lee D said:

 It can be kept to a minimum if you pixel align the objects but it will be more noticeable on objects with a curved or diagonal edge.

If the object perimeters have exactly the same data; the same coordinates, and sizes, then the object behind shouldn't show through. The approach should not to be to render an object then render another object on top, but to calculate all objects together for a final composite then render the result. I've not tried rendering to a raster format, but it is noticeable on PDF output. Of course I can get around this, I'm just not used to having to take the extra steps. In the most part making "compound" objects is useful in dealing with my particular design issues; preserving hidden geometry for future use/reference/variations. Cheers.