Nodes

[ShaneP]

When I make a file in CorelDraw , I typically go through and try to remove as many nodes as possible, then save as a DXF. I have noticed that when I open that file again, all those deleted nodes are there again. What am I doing wrong?

[adbuch]

After your node edit perhaps save the file first in .cdr format, then export the dxf. Also - are you opening (importing) your saved dxf or opening your original file?

David

[ShaneP]

So I just chose a random file and it opened with 3573 nodes. I edited it to 502 nodes and saved as CDR, then exported to DXF. When I opened it again it had 3573 nodes. I also tried to import it with the same results. I am saving as polycurves not splines, not sure if that makes a difference or not.

[ShaneP]

Tried again saving as splines instead of polycurves and it opens with 502 nodes. So I guess it does make a difference.

[kicktillmonday]

How are you saving it as splines from Corel Draw? I didn't know that was possible and would certainly be helpful.

[ShaneP]

Screenshot 2024-09-18 111412.png (23.7 KiB) Viewed 3953 times

Screenshot 2024-09-18 111412.png (23.7 KiB) Viewed 3953 times

Where it says "Export Curves As:" you can change from polycurve to splines in the drop down.

[tcaudle]

So I just chose a random file and it opened with 3573 nodes. I edited it to 502 nodes and saved as CDR, then exported to DXF. When I opened it again it had 3573 nodes. I also tried to import it with the same results. I am saving as polycurves not splines, not sure if that makes a difference or not.

Welcome to the CorelDraw DXF export filter. It does not support arcs. curves or polylines no matter what format the inport DXF is in..

If you want the arcs and bezier curves to come across intact use the SVG export or save in Coreldraw X14 format and import into Inkscape as CDR . Its SVG export loads directly to any CAM (like SheetCAM) that supports SVG imports.

Another work around is to export from Coreldaraw to PDF and then import to Inkscape.

ORCAD Pro will impirt DXF or DWG and export in SVG . The DXF has to be one that has the support for polylines and arcs ( a lot of older ones do not)

[adbuch]

So I just chose a random file and it opened with 3573 nodes. I edited it to 502 nodes and saved as CDR, then exported to DXF. When I opened it again it had 3573 nodes. I also tried to import it with the same results. I am saving as polycurves not splines, not sure if that makes a difference or not.

I opened CorelDraw 2020 and imported a "random" dxf that was originally saved from Inkscape. I deleted some of the nodes, exported as dxf and also saved in .cdr format. After the node edit, I did Group and Join Curves before saving and exporting - which I normally do with any file before saving or exporting with CorelDraw.

Then I closed CorelDraw, opened the saved .cdr file, and it appears to be exactly the same as when I saved it.



David

[ShaneP]

Thank you all for your responses. I think I will start saving as SVG from now on.

[kicktillmonday]

Screenshot 2024-09-18 111412.png

Where it says "Export Curves As:" you can change from polycurve to splines in the drop down.

Thanks Shane. I checked my Corel 2018 and that option does not exist. Bummer.

I opened CorelDraw 2020 and imported a "random" dxf that was originally saved from Inkscape. I deleted some of the nodes, exported as dxf and also saved in .cdr format. After the node edit, I did Group and Join Curves before saving and exporting - which I normally do with any file before saving or exporting with CorelDraw.

Then I closed CorelDraw, opened the saved .cdr file, and it appears to be exactly the same as when I saved it.

David, eliminating nodes, saving as cdr and re-opening the cdr I would expect the node reduction to still be intact. I believe what Shane was referring to was saving his cdr file as a dxf and then opening the dxf to prepare it to cut and the node count went back up from where it was in the cdr file. Using the spline option seemed to keep his node count down, unfortunately my Corel does not have this option.

[adbuch]

I have noticed that when I open that file again, all those deleted nodes are there again. What am I doing wrong?

What program are you using to open that dxf file again? I had assumed you were reopening it with CorelDraw. Which program are you opening it with where "all those deleted nodes are there again"?
David

[adbuch]

David, eliminating nodes, saving as cdr and re-opening the cdr I would expect the node reduction to still be intact. I believe what Shane was referring to was saving his cdr file as a dxf and then opening the dxf to prepare it to cut and the node count went back up from where it was in the cdr file. Using the spline option seemed to keep his node count down, unfortunately my Corel does not have this option.

I don't really know what Shane was referring to, or what program he was using do open the dxf file that he saved/exported from CorelDraw. In any case, here is an example showing a CorelDraw drawing file (before and after) edited to reduce nodes, exported as dxf, and then opened with both Inkscape and SheetCam for comparison. You can draw your own conclusions from the screen shots below.

David

[tcaudle]

So I just chose a random file and it opened with 3573 nodes. I edited it to 502 nodes and saved as CDR, then exported to DXF. When I opened it again it had 3573 nodes. I also tried to import it with the same results. I am saving as polycurves not splines, not sure if that makes a difference or not.

I opened CorelDraw 2020 and imported a "random" dxf that was originally saved from Inkscape. I deleted some of the nodes, exported as dxf and also saved in .cdr format. After the node edit, I did Group and Join Curves before saving and exporting - which I normally do with any file before saving or exporting with CorelDraw.

Then I closed CorelDraw, opened the saved .cdr file, and it appears to be exactly the same as when I saved it.



David

Yeah I typically use CorelDraw X16 . I opened my 2019 version and did an export and it looks like they finally fixed the export filters to do the arcs . Thats a lot beetler than many years of the old export filter .

[kicktillmonday]

David, eliminating nodes, saving as cdr and re-opening the cdr I would expect the node reduction to still be intact. I believe what Shane was referring to was saving his cdr file as a dxf and then opening the dxf to prepare it to cut and the node count went back up from where it was in the cdr file. Using the spline option seemed to keep his node count down, unfortunately my Corel does not have this option.

I don't really know what Shane was referring to, or what program he was using do open the dxf file that he saved/exported from CorelDraw. In any case, here is an example showing a CorelDraw drawing file (before and after) edited to reduce nodes, exported as dxf, and then opened with both Inkscape and SheetCam for comparison. You can draw your own conclusions from the screen shots below.

David

Looks like Tom from C&CNC has the answer to this in his lastest post to this topic David. Tom says that it appears as though Corel fixed the dxf export issue in 2019. I see your using 2020 David so makes sense your dxf are showing up with your node reduction intact. My version is 2018 So much to be learned here, I love it!

[ShaneP]

I mainly use CorelDraw, occasionally Fusion 360 for parts and SheetCam to post process. I have tried this with other files as well and seems that saving with splines will keep node count intact when exporting to DXF. Saving as polycurves does not. I am using version 24.5.0.731 September 2023 btw.

[adbuch]

Looks like Tom from C&CNC has the answer to this in his lastest post to this topic David. Tom says that it appears as though Corel fixed the dxf export issue in 2019. I see your using 2020 David so makes sense your dxf are showing up with your node reduction intact. My version is 2018 So much to be learned here, I love it!

Kicktilmonday - I'm using both 2020 and 2021, and neither one offers specific export options for splines, curves, polylines, etc. If they fixed it with the 2019 version and the OP is using the 2023 or 2024 version, then it sounds like CorelDraw is going backwards.

David

[tcaudle]

I dunno. For years the DXF export filter in CorelDraw only exported in line segments . No arcs, no curves , no poly-anything. It was so bad at one point that a third party put out a converter (DXF Tool) that exported the files with the arsc and curves. Then Les at SheetCAM put in support for SVG imports and the problem was resolved. For a long time most DXF IMPORT filters would not support polylines or arcs either . You had to export in R13/R14 or they would puke SBG is a documented format taht was originally developed to display vector drawings on web pages . Inkscape is the first package I am aware of that uses SVG as its native file format instead of a proprietary file format . With each release of Inkscape they have improved the Import and Export filters , Like Coreldarw they add lots of drawing tools not needed for doing CNC work but you learn to ignore the tools you never use.

Not sure when CorelDraw went to the "rent" model but I know they also have different levels that may not have all of the features.....I don't use software i have to pay ransom for or its done in the "Cloud" . While I agree that Fusion 360 has the easiest 3D drawing tools, I can't justify the cost for as little as I use it and I do not qualify for the hobby version..

Since CorelDraw only runs on Windows and I only have one Windows PC I use it relegated to just an occasional usage. I have hundreds if not more CDR fiiles (some are many pages long) I still need access to . While drawings can be exported using SVG or PDF, paragraph text has problems. Formatting in CorelDraw is somewhat proprietary and an export comes across in line or (worse) word segments and sometimes in poor alignment and spacing. Its easier to re-type the text than to try and edit it back to something usable.

[adbuch]

Regardless of the version - it makes no sense to me that it would not save to .cdr format in the edited form (after node edit).

David

[kicktillmonday]

Regardless of the version - it makes no sense to me that it would not save to .cdr format in the edited form (after node edit).

David

I don't believe that was the issue though David, the node edit would have to be saved in the .cdr. I believe he was node editing and sending it for PP and seeing the node count go up. As for Corel, I like the software but they are inconsistent, greedy, and customer service could use some work.

[adbuch]

Regardless of the version - it makes no sense to me that it would not save to .cdr format in the edited form (after node edit).

David

I don't believe that was the issue though David, the node edit would have to be saved in the .cdr. I believe he was node editing and sending it for PP and seeing the node count go up. As for Corel, I like the software but they are inconsistent, greedy, and customer service could use some work.

As far as I know, he never told us what program he was using to open the saved dxf. I still think there is something going one here - perhaps with his node edit technique or how he edits it withing CorelDraw (after node edit and before exporting as dxf). Did he "Join Curves" and/or combine before export?
I expect that to really get to the bottom of this I would need to download the CorelDraw version he is using and try to replicate his problem.

David

[ShaneP]

I am using Corel to reopen the file. If I save as a cdr file, the cdr file opens fine after editing nodes with the same node count as when saved. It's when I save as a DXF then reopen the file in Corel where I was having the issue. As I mentioned earlier, my version gives the option to save the DXF with curves exported as either polylines or splines. I had left it on polylines as I believe that's what it defaults to. Using this method, when I reopened the file in Corel, the node count would go back to what it had been before editing. I opened my edited CDR and exported to DXF again and changed from polyline to spline and this seem to have corrected the issue. Now when I reopen the DXF saved with splines in Corel, the edited node count stays intact, same with exporting as SVG. I don't normally join curves before saving, but I do use the smartfill tool so I can export a jpeg or png. I could be wrong, but my understanding is using the smartfill tool also welds/combines.

[adbuch]

I just installed CorelDraw 2024 to check it out. For dxf export it offers 2 choices - polycurves or splines. For my fresh install the default was "splines" for the dxf export operation. I tried a simple node edit, exported as dxf, and reopened with CorelDraw 2024.

Then I changed the dxf export option from splines to polycurves.

[adbuch]

I don't normally join curves before saving, but I do use the smartfill tool so I can export a jpeg or png. I could be wrong, but my understanding is using the smartfill tool also welds/combines.

Shane,

The smart fill tool is one I have not used before. I will have to check it out. Thanks for the suggestion!

David

[tcaudle]

There are two places a file can get changed . The Export FILTER is an interpreter that assembles the export file in a structured way and with most file formats uses the documented standards to build the file. If the filter cannot or does not handle a specific feature it either skips it or falls back to a default it can use.

The import filter reads the exported file and does its best to translate it into the format THAT package can best handle. Once again it relies on documented standards.

When you have formats like EPS, PDF, SVG , WMF that have documented standards and not one company or person sets or can change those, than it prevents chaos in the exchange process. You can get documents of most of the standards. EPS and PDF have roots in Postscript an Adobe invention , but they are open source and handled like a programming language.

Some other formats are not open and are either proprietary or lightly documented and can get changed any time the owner wants.

When you build an Import filter you have to go with the core features you know will work with most exports . The import filter can mess things up too but typically it did not add in nodes that are not there.

Back in the DOS days with every manufacturer writing their own drivers and their own export and import filters it was a nightmare to get things to work together. Windows DID fix a lot of that because it had a documented set of rules for drivers and file formats and to be Windows compliant you had to use those drivers . That was probably the best contribution that Windows made and that made hardware and software all work better together.

DXF grew up in a different neighbourhood. It came out of pure CAD that was basically Mechanical Drafting using basic lines and arcs for 2D. great for drawing buildings , building mechanicals ,machinery and line drawings. DXF was a file transfer intended for viewing or pruning a view A whole different kind of need came up in the 80's for more artistic tools for Desktop Publishing, Silk Screen Printing, Illustration and side arts like embroidery and sign making. Those "arts" were more free-form and visual. I guess CNC started out more pure mechanical and fabrication based so it was in a CAD camp in the beginning. Now its morphed into both worlds and with CNC routers used in decorative cutting signs and decorative plasma its often outside pure CAD .
Most CAD systems of the 80's and 90's did not support Fonts or doing things like wrapping text to a shape . They
did not do fills or much with colors.

The first CNC machines I came in contact with were CNC mills, CNC punch presses and PCB Drilling machines . Less used were CNC lathes and cutting machines like plasma and router.

[adbuch]

Tom - thanks for providing that additional perspective!
David