Klipper GCode Preprocessor for Object Cancellation

This preprocessor modifies GCode files to add klipper's exclude object gcode.

The following slicers are supported:

• SuperSlicer
• PrusaSlicer
• Slic3r
• Cura
• IdeaMaker

Installation and usage

SuperSlicer, PrusaSlicer, and Slic3r

Download the provided binary for your platform, and place it in with in your slicer's folder.

In your Print Settings, under Output Options, add preprocessor.exe; to the "Post-Processing Scripts". For mac or linux, you should just use preprocessor;

Then, all generated gcode should be automatically processed and rewritten to support cancellation.

G-Codes for Object Cancelation

There are 3 gcodes inserted in the files automatically, and 4 more used to control the object cancellation.

DEFINE_OBJECT NAME=<object name> [CENTER=x,y] [POLYGON=[[x,y],...]]

The NAME must be unique and consistent throughout the file. CENTER is the center location for the mesh, used to show on interfaces where and object being canceled is on the bed. POLYGON is a series of points, used to represent the bounds of the object. It can be just a bounding box, a simplified outline, or another useful shape.

START_CURRENT_OBJECT NAME=<object name> and END_CURRENT_OBJECT [NAME=<object name>]

The beginning and end markers for the gcode for a single object. When an object is excluded, anything between these markers is ignored.

LIST_OBJECTS LIST_EXCLUDED_OBJECTS EXCLUDE_OBJECT NAME=<object name> REMOVE_ALL_EXCLUDED

These gcode are used by the user to locate objects, and control which are canceled. These are mostly utility, to be functional without the need for a full frontend for the printer.

Known Limitations

Cura and Ideamaker sliced files have all support material as a single non-mesh entity. This means that when canceling an object, it's support will still print. Including support that is inside or built onto the canceled mesh. The Slic3r family (including PrusaSlicer and SuperSlicer) treat support as part of the individual mesh's object, so canceling a mesh cancels it's support as well.

How does it work

This looks for known markers inside the GCode, specific to each slicer. It uses those to figure out the printing object's name, and track's all extrusion moves within it's print movements. Those are used to calculate a minimal bounding box for each mesh. A series of DEFINE_OBJECT gcodes are placed in a header, including the bounding boxes and objects centers. Then, these markers are used to place START_CURRENT_OBJECT and END_CURRENT_OBJECT gcodes in the file surrounding each set of extrusions for that object.