Lionel Seidman

It looks like AI has solved the problem, so it must be possible, right?

I understand that anti-aliasing is being applied as we convert vector data into raster data, but what I am saying is that the way in which the anti-aliasing is being applied is creating faulty output in which the background color is improperly bleeding through.
 
Let's suppose we have a pixel that is exactly on the seam between two objects.  One way to render that pixel would be to draw object number one using anti-aliasing (giving us a 50/50 mix of the object color and the background color) and then to draw object number two using anti-aliasing, giving us a 50/25/25 mix of objects 2, 1, and the background color.  This appears to be the way Designer is doing things right now, and as you can see this gives us the wrong result!  The final color for this pixel should be a 50/50 mix of the color in objects 1 and 2, with no weight given to the background color.
 
It is definitely possible to achieve correct looking output in this situation, and we know that other programs are already doing so, such as Ai.
 
What I am looking for is someone within the Designer team to address this concern to.  If this is the wrong channel for that, I'd appreciate if someone could point me in the right direction.

@TonyB Thanks for the informative reply.
 
If you do go down the multisampling route, you should be able to get pretty good quality anti-aliasing by using 8x multisampling (i.e. 64 samples per pixel) or higher.  The downside there would be potentially slower performance during image exporting, but if the user wants high-quality exports I think they'll be willing to wait a couple of seconds.  It would be nice to have that option, at least.

The geometry isn't really the concern here.  The problem is the seam between one polygon and another.  Ai handles these sorts of seams quite nicely, while Designer does not, so in that sense, Ai is more accurate.

I didn't mean to say that the geometry is of no concern to me in general, just that the geometry of the shapes looks fine, and that I am not concerned about it misbehaving.
 
The only thing I am concerned about is the seams between pieces of geometry.  If two pieces of geometry are exactly adjacent to each other, and when we rasterize the geometry we are able to see remnants of the background color showing through the seams, then I would say the program is misbehaving.

@TonyB Thanks for the informative reply.
 
If you do go down the multisampling route, you should be able to get pretty good quality anti-aliasing by using 8x multisampling (i.e. 64 samples per pixel) or higher.  The downside there would be potentially slower performance during image exporting, but if the user wants high-quality exports I think they'll be willing to wait a couple of seconds.  It would be nice to have that option, at least.

I didn't mean to say that the geometry is of no concern to me in general, just that the geometry of the shapes looks fine, and that I am not concerned about it misbehaving.
 
The only thing I am concerned about is the seams between pieces of geometry.  If two pieces of geometry are exactly adjacent to each other, and when we rasterize the geometry we are able to see remnants of the background color showing through the seams, then I would say the program is misbehaving.

The geometry isn't really the concern here.  The problem is the seam between one polygon and another.  Ai handles these sorts of seams quite nicely, while Designer does not, so in that sense, Ai is more accurate.

I understand that anti-aliasing is being applied as we convert vector data into raster data, but what I am saying is that the way in which the anti-aliasing is being applied is creating faulty output in which the background color is improperly bleeding through.
 
Let's suppose we have a pixel that is exactly on the seam between two objects.  One way to render that pixel would be to draw object number one using anti-aliasing (giving us a 50/50 mix of the object color and the background color) and then to draw object number two using anti-aliasing, giving us a 50/25/25 mix of objects 2, 1, and the background color.  This appears to be the way Designer is doing things right now, and as you can see this gives us the wrong result!  The final color for this pixel should be a 50/50 mix of the color in objects 1 and 2, with no weight given to the background color.
 
It is definitely possible to achieve correct looking output in this situation, and we know that other programs are already doing so, such as Ai.
 
What I am looking for is someone within the Designer team to address this concern to.  If this is the wrong channel for that, I'd appreciate if someone could point me in the right direction.

Rather than addressing your explanation, why don't we just go head to head.
 
Your file (with a curve added) in all black to really get a good look, saved as a png from AffinityD and from Illustrator.
I'll let you guess which is which.
(the difference is actually much more pronounced out of a browser (mine at least)... such as in AD itself and elsewhere like Preview)
 
 
 
 
The fact that they call this normal is the most distressing thing of all. If it's so normal why are there constantly people trying to come over from Ai saying "HEY what's up with these lines??"
It's like they've resigned themselves to this result. At one point I remember a response from the Devs that included something like.... but we're working on improving this. But I haven't seen that included in a reply for a long time. It would be nice to at least "hear" again.
Or maybe it's just not resolvable with the render engine approach they've chosen?
I'm not saying AI is perfect all the time, but come on right? Night and day.