Cura 5.14 alpha ~ Paint-on Support

[HellAholic]

Cura 5.14 alpha ~ Paint-on Support, Template Variables Expansion, Windows ARM, and Qt6 Upgrade

Hi everyone! 👋

We’ve been working hard behind the scenes on some major foundational updates, feature expansions, and highly requested optimizations. As always, experimental and pre-release builds are an opportunity to showcase what’s coming, gather your feedback, and ensure stability before a final roll-out.

Please note that these features are a work in progress, and we welcome your detailed discussion, bug reports, and suggestions right here!

⚠️ Alpha's and 'nightlies' are experimental builds -- please use this release in an exploratory fashion only, please do not rely on it for important tasks like production. This build will also not receive any official support -- it is purely to (showcase and) facilitate discussion of new features within the Cura-community.

🎨 Feature Expansion: Paint-on Support

Building upon our existing paint-on functionalities (like material and seam painting), we have officially expanded the toolset to include Paint-on Support. You can now intuitively brush support generation zones directly onto your 3D models for granular, localized control without needing to rely entirely on automated support angles or support blocker meshes.

🚀 Expanded Template Variables in Start/End G-code

We have updated the internal architecture where template variables within the machine and extruder start/end G-code are resolved. In this updated system, variables are evaluated at a later stage in the slicing pipeline, allowing us to expose highly requested dynamic print-job data that wasn't previously accessible!
Here are the new variables you can now utilize in your custom configurations:

Machine End G-code Variables

Extra Variable	Type	Description
initial_layer_bb_min_x, initial_layer_bb_max_x, initial_layer_bb_min_y, initial_layer_bb_max_y, initial_layer_bb_width, initial_layer_bb_height	float	Bounding box dimensions of the initial layer (in mm)
total_bb_min_x, total_bb_max_x, total_bb_min_y, total_bb_max_y, total_bb_min_z, total_bb_max_z, total_bb_width, total_bb_depth, total_bb_height	float	Bounding box dimensions of the entire printed target (in mm)
is_extruder_used	[bool]	A list indicating whether each extruder is used in the print job

Extruder Start / End G-code Variables

Extra Variable	Type	Description
previous_extruder_nr	int	The index of the extruder used before executing the start/end extruder code
next_extruder_nr	int	The index of the extruder used after executing the start/end extruder code

💡 We Want Your Feedback: What Variables Are We Missing?

Because these templates are now resolved later in the slicing pipeline, we can finally tap into real-time printer state data that wasn't accessible before. We want to make this system as powerful as possible for your custom setups. For example, we could now potentially expose things like current nozzle temperature(s) right when the G-code is generated.
What other variables would make your workflow easier? Drop your ideas and use cases in the comments below, and let's see what we can add!

💻 Experimental Windows ARM Support

We have put together an experimental test build for Windows on ARM. Please note that this is strictly a trial to gauge performance and stability in real-world environments, and it does not represent an official commitment to support the ARM ecosystem in future releases. Feedback from users running ARM-based hardware is highly appreciated to help us evaluate its long-term viability!

💥 Crash Reductions & Slicing Stability

Slicing stability remains a core priority. We have dedicated focused engineering efforts to isolating and fixing common edge-case slice crashes. Complex geometries and high-density meshes should now process much more reliably.

🔧 Under the Hood: The Qt6 Upgrade (Plugin Compatibility Notice)

We have upgraded our underlying UI framework from Qt 6.6 to Qt 6.10. While the API itself is structurally very similar, this underlying framework transition has the potential to break some existing community plugins.

• Our goal: We would strongly prefer not to force an immediate SDK major upgrade that invalidates all existing marketplace plugins.
• The plan: We are actively testing to see if we can maintain backwards compatibility. If we discover widespread incompatibilities that cannot be bridged natively, we might be forced to issue an SDK bump.
• Call to action for developers: If you maintain a Cura plugin, please test your plugin on this build and let us know your findings in the comments below!

🎁 Other Changes

All of this is built on top of our (current) in-progress work for the upcoming release, so you might see some other features pop-up, such as:

• Dialogs that were previously created at application boot are now created only when necessary, which saves some boot time and memory
• Discard top and bottom surfaces when their settings are identical to skin settings, which avoids printing them separately
• Discard very thin infill areas that are printed within skin and disrupts the flow
• Improve positioning of models when loading multiple models from a non-project 3MF file
• Improved the OpenGL shaders compatibility, contributed by HellAholic
• Introduced Top/Bottom/Skin Merge Distance, which allows merging those areas together when they are too small to be printed correctly
• Introduced Minimum Infill Line Length, which allows removing unnecessary lines of infill added in small areas
• Removed an unnecessary and long travel move added when printing supported floating models
• Fixed an issue where top and bottom surfaces could be generated, although they were disabled
• Fixed the print temperature command of the initial layer when using the 'zigzag' pattern, contributed by HellAholic
• Fixed an issue where the project window could be displayed at an unexpected position
• Removed hardcoded T0 in start gcode for anycubic ACE PRO enabled K3
• Fixed multiple bugs in Elegoo Neptune 3 Pro: acceleration, retraction_combing, end gcode

🪲 Known Issues & What to Look Out For

Because this is an experimental phase, you might encounter a few hiccups:

• UI or rendering bugs related to the Qt6 shift.
• Potential lag spikes or feedback delays while using the new Paint-on Support brush on exceptionally dense meshes.

Please drop your thoughts, logs, and findings below. Happy testing!