Hi Friends, I sent this message earlier, but the attachment has apparently put it over the size limit. So it's waiting for a moderator, for now. But perhaps could be answered without the PNG. So just in case, here's the message, and if the screenshot is needed, I'll try to figure some way to send it. Original message below: This is something I noticed a long, long time ago, and never really questioned. But now I'm writing a tutorial about node editing, and it seems a good time to find out. When more than 1 node are all stacked up, precisely on top of each other -- if it's an even number of nodes, then they appear to be smaller than a regular node. (see in the top aqua circle in the attached ne12.png) It's what you see if you use "Break path at selected nodes". But if there are an odd number of nodes all stacked up, it looks just like a regular node. So there's no visible clue -- you only know how many nodes might be there, if you happen to select them (by dragging a selection box around), or if you already know, or happen to remember what's there. I'm curious why it's made that way, and whether it might be helpful if any number of stacked up nodes can look like the even number of stacked up nodes (just a smaller node). Well, I would find it helpful anyway, and wonder if others might as well. I'd appreciate if anyone can explain.
Thank you very much, brynn
Hi again, And there's a similar difference when these nodes are selected. If it's an even number of nodes that are selected, it actually looks like there are no nodes there at all -- they appear to have disappeared! Yet if it's an odd number of nodes that are selected, it looks like just 1 node is selected. Just curious :-)
TA brynn
-------------------------------------------------- From: "Brynn" <brynn@...3133...> Sent: Sunday, November 01, 2015 7:47 AM To: "Inkscape-Devel" Inkscape-devel@lists.sourceforge.net Subject: [Inkscape-devel] question about nodes display
Hi Friends, I sent this message earlier, but the attachment has apparently put it over the size limit. So it's waiting for a moderator, for now. But perhaps could be answered without the PNG. So just in case, here's the message, and if the screenshot is needed, I'll try to figure some way to send it. Original message below: This is something I noticed a long, long time ago, and never really questioned. But now I'm writing a tutorial about node editing, and it seems a good time to find out. When more than 1 node are all stacked up, precisely on top of each other -- if it's an even number of nodes, then they appear to be smaller than a regular node. (see in the top aqua circle in the attached ne12.png) It's what you see if you use "Break path at selected nodes". But if there are an odd number of nodes all stacked up, it looks just like a regular node. So there's no visible clue -- you only know how many nodes might be there, if you happen to select them (by dragging a selection box around), or if you already know, or happen to remember what's there. I'm curious why it's made that way, and whether it might be helpful if any number of stacked up nodes can look like the even number of stacked up nodes (just a smaller node). Well, I would find it helpful anyway, and wonder if others might as well. I'd appreciate if anyone can explain.
Thank you very much, brynn
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On Sun, 2015-11-01 at 07:47 -0700, Brynn wrote:
When more than 1 node are all stacked up, precisely on top of each other -- if it's an even number of nodes, then they appear to be smaller than a regular node. (see in the top aqua circle in the attached ne12.png) It's what you see if you use "Break path at selected nodes".
The effect is caused by the "inverted colours" effect the nodes have when they are being drawn. There is no consideration of existing nodes already on that space and so they're just drawn on top of each other flipping from one apparent state when even to another when odd counted.
One can also see this when two nodes are very close to each other enough to overlap.
Martin,
What do you mean by "inverted colors" effect?
-------------------------------------------------- From: "Martin Owens" <doctormo@...400...> Sent: Sunday, November 01, 2015 11:27 AM To: "Brynn" <brynn@...3133...> Cc: "Inkscape-Devel" Inkscape-devel@lists.sourceforge.net Subject: Re: [Inkscape-devel] question about nodes display
On Sun, 2015-11-01 at 07:47 -0700, Brynn wrote:
When more than 1 node are all stacked up, precisely on top of each other -- if it's an even number of nodes, then they appear to be smaller than a regular node. (see in the top aqua circle in the attached ne12.png) It's what you see if you use "Break path at selected nodes".
The effect is caused by the "inverted colours" effect the nodes have when they are being drawn. There is no consideration of existing nodes already on that space and so they're just drawn on top of each other flipping from one apparent state when even to another when odd counted.
One can also see this when two nodes are very close to each other enough to overlap.
Martin,
What do you mean by "inverted colors" effect?
Because node markers could be over any colour (even the default colour for markers) a trick to keep them visible at all times is to calculate what the inverse of the colour under the node marker is and make the node market the inverse of that colour, to provide a high-contrast marker no matter what the colour under it is.
Unfortunately, when two markers are atop each other, they are both set to be the inverse of the colour under it, the effect is that the cancel eachother out, and thus disappear instead of standing out.
Walking through and example:
Let's say the bottom colour is yellow, the node marker over it would be inverted into purplish colour. This is the desired effect, because we can easily see the node in contrast to the yellow object underneath. Now if there's another node on top of that: The node on top of that takes the inverse of the purple colour node under it, and turns it back to yellow (the inverse of purple), and thus it looks like the markers have vanished. They haven't actually vanished, it's just that the top node turned it's colour to the same colour as the yellow under both nodes (the inverse of the inverse of yellow is yellow).
So what we really want is for the nodes to ignore the colour of other nodes under them, so if they are stacked, it only takes into account the colour of non-node objects to perform the inverse. Additionally, it would be handy to have, at the center of each node marker a single pixel-width dot representing the true center of the node marker. This way, even though the nodes would be the same colour, you still have a chance of distinguishing that there are 2 nodes atop each other... or you can just zoom in enough to where they don't overlap, of course. :)
-C
Oh ok, I understand now.
Thank you Martin and CR for taking the time to explain :-)
All best
_________________________
From: C R Sent: Sunday, November 01, 2015 1:14 PM To: Brynn Cc: Inkscape-Devel Subject: Re: [Inkscape-devel] question about nodes display
What do you mean by "inverted colors" effect?
Because node markers could be over any colour (even the default colour for markers) a trick to keep them visible at all times is to calculate what the inverse of the colour under the node marker is and make the node market the inverse of that colour, to provide a high-contrast marker no matter what the colour under it is.
Unfortunately, when two markers are atop each other, they are both set to be the inverse of the colour under it, the effect is that the cancel eachother out, and thus disappear instead of standing out.
Walking through and example:
Let's say the bottom colour is yellow, the node marker over it would be inverted into purplish colour. This is the desired effect, because we can easily see the node in contrast to the yellow object underneath. Now if there's another node on top of that: The node on top of that takes the inverse of the purple colour node under it, and turns it back to yellow (the inverse of purple), and thus it looks like the markers have vanished. They haven't actually vanished, it's just that the top node turned it's colour to the same colour as the yellow under both nodes (the inverse of the inverse of yellow is yellow).
So what we really want is for the nodes to ignore the colour of other nodes under them, so if they are stacked, it only takes into account the colour of non-node objects to perform the inverse. Additionally, it would be handy to have, at the center of each node marker a single pixel-width dot representing the true center of the node marker. This way, even though the nodes would be the same colour, you still have a chance of distinguishing that there are 2 nodes atop each other... or you can just zoom in enough to where they don't overlap, of course. :)
-C
participants (3)
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Brynn -
C R -
Martin Owens