Just for kicks, I opened a .blend created in 2.8 in 2.81 (version: 2.81 (sub 13), branch: master, commit date: 2019-10-03 21:03, Darwin) and saved it as a new file, no changes.
Here’s a screenshot of the Node editor…
Opening the new file in 2.8 gives me this…
??? I see that the Mapping node has changed slightly from 2.8 to 2.81 but apparently the information, while being the same (I checked the Scale setting in this Undefined node), isn’t translated back. Is this a bug or does this mean that 2.81 files can’t be faithfully read by 2.8?
For me it’s pretty much “normal”. there is already a work done on retrocompatibility (Latest Release are always able to open file saved on older releases, even between 2.8 and 2.79)
But the other way… I think there is no reasonable usecase where you should go back to an older release and open a newer file…
the texture procedural shaders have been improved and expanded a lot, especially with the GSoc 2019, so some parts have been rewritten for the better, but inevitably the compatibility with some old nodes is lost
I do agree with you for the most part, progress must go forward, but…
Because as of today 2.81 is in Alpha, but I’d like to acquaint myself with the changes without being marrying to it…yet. Not everyone is a madman (like myself and present company ) and uses Alpha-stage software, so exchanging files becomes difficult (already, only four months after an enormous change).
Because, in my original example, it’s just a Mapping node that’s existed since…gosh, I can’t remember…and really, only the layout has changed (IMHO for the better) but the contained information doesn’t. I don’t understand why a simple UI change results in a “Undefined” node. The Principled Shader node (for example) has changed but there’s no problem there.
Because we as software users have become too used to New Version Incompatabilty Syndrome. Imagine if you had to update your image editing software every time the JPEG/PNG/TIFF/whatever format was updated. Using Photoshop/GIMP as examples, saving in native format .PSD/.XCF you are at least given the option to save in a backward-compatible version or not. An 180° example of this is with Microsoft Word, forcing an (paid) upgrade every time Microsoft updates. You now have incompatible Word 2007 (.docx), Word 2003 (.doc), Word 97 (.doc). Or that other evil empire Adobe, with the Illustrator/After Effects formats. In their defense, at least these major incompatibilities happen once every X years.
For example to use BlenderXR. They just made the update to 2.80 a month ago. This bug is unfortunately very irritating. Sometime it opens the file with an undefined node, sometimes it crashes outright.
A few months of forwards compatibility would be nice. At least it shouldn’t crash if something is not recognised in the file.
Yes, having a backwards compatible saving mode would be a great idea!
You say Microsoft Word is 180° opposite, but I think they handled the switch from *.doc to *.docx pretty well, the users had years and years to make the change. I used the doc format for years exactly for compatibility reasons, before switching to docx, and never had any notable problems.
The main issue here, is that the .blend container isn’t a true fixed file format ike .txt or .html or others. It works essentially as a memory dump of Blender’s internal DNA structure, meaning that when Blender changes, so does the associated .blend file.
Sucn incompatibilities happen with literally every minor release, also before 2.80. When a new node is added, and if you use that node and open your file in an earlier version of Blender, what is Blender supposed to do?