Updates:

• 2022/02/20: finally published
• 2022/02/08: ready to publish finally with some delay
• 2022/01/28: not yet published, removed Universal Slicing details for future blog-post, added more photos and illustrations
• 2022/01/16: starting write-up

Introduction

Aside of the technical detailed filled blog-posts I like to start to post about the larger context of my inner motivations doing XYZdims.com – this is the first post “XYZdims State 2022/02”:

More Slicers

Recent in-house developments having more slicers to experiment with, in regards of slicing techniques as well lay the ground for more complex slicing and mapping/transformation operations to support arbitrary non-planar slicing (coming soon).

LabSlicer: The Mother

As I was working with Slicer4RTN and wrappers like Cura-CLI-Wrapper and Kiri:Moto Slicer (CLI wrapper), and adopting Mandoline fork – I realized I need to have my own slicer, so in November 2021 I started from scratch, as I thought I need to know every detail and so I exposed each step or stage:

• mesh: load mesh, vertices & faces
• slice: slice layers into sets of polygons
• route: route the layer polygons with walls, infills etc
• gcode: convert routes to G-code

A “lab(oratory) slicer” or simply LabSlicer was born – I defined each stage: API and file-format it takes in and spits out.

After a couple of weeks I had slicing into polygons, and routing of walls, basic infills, skirts, brims and eventually intermediary top & bottom layers resolved, and I was able to generate printable gcode:

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Meanwhile LabSlicer as of version 0.1.5 has matured to print complex models reliably but rather performs slow compared to Slic3r or Cura.

As of 2022/02 I’m even use LabSlicer and its relatives (featured below) for productive 3D prints.

Vox3lSlicer: Voxels

Aside of LabSlicer I began to develop Vox3lSlicer which utilizes internally the OpenVDB voxel library, in order to slice planar and in the future non-planar as well, and also permit to slice voxel-based models efficiently.

A few tests with OpenSCAD Logo model (~20mm height) with various amount voxel samples, from low resolution to high resolution:

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and with defined voxel sizes:

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As LabSlicer matured and LabSlicerCore library came to life, Vox3lSlicer (2011/11) utilizes the stage route and gcode of LabSlicerCore to actually produce printable G-code.

Testing the retraction code and settings of Vox3lSlicer, rotating the model in order to avoid support structure altogether:

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VoxGLSlicer: OpenGL Slicing

As I was looking for other slicing procedures I came across OpenGL-ST-Slicer, which utilizes a clever OpenGL setup with GLSL (Shader Language) to render a mesh to a framebuffer with the volume information, and so slicing is done solely in the GPU almost instantly – I extended this approach and glued it together with LabSlicerCore and I was able to produce also printable G-code – VoxGLSlicer was born (2022/01).

Due the limitation of the internal framebuffer width & height the resolution of the slicing changes with the size of the model aka “relative resolution”:

model width [mm]	pixel size [mm] @ 2560 pixels
20	0.008 or 8 μm
50	0.019 or 19 μm
100	0.039 or 39 μm
200	0.078 or 78 μm
500	0.19 or 195 μm
1000	0.39 or 390 μm

and just for illustration about “pixel size” related to a ~20mm model:

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3 Slicers

After a few weeks coding (2021/11-2022/01), I was able to raise 3 slicers, each with their unique slicing approaches to create printable G-code, by having a common API and use symbiotic advantage of each other:

	LabSlicer	Vox3lSlicer	VoxGLSlicer
mesh	mesh.py1) multi-format mesh importer	openvdb STL importer	mesh.py1) multi-format mesh importer
slice	slicing mesh to polygons (vectorizing)	slice voxels into polygons (vectorizing)	screenbuffer into polygons (vectorizing)
route	route polygons to routes	LabSlicerCore’s route	LabSlicerCore’s route
gcode	convert routes to G-code	LabSlicerCore’s gcode	LabSlicerCore’s gcode
	+ traditional slicer with polygons + all stages fully implemented – slow slicing2)	+ fast slicing + flexible resolution + reliable	+ fast slicing – fixed screenbuffer size – relative resolution

All three slicers are very experimental and play a significant role for the next step – Universal Slicing.

Footnotes:

1. mesh.py is loading/saving 3d meshs/models and some simple manipulations tuned toward my use cases
2. mesh slicing not yet optimized

So any optimizing of routing (wall, infill, intermediary top/bottom layers etc) and gcode optimizing all three slicers benefit from.

YAGV & Nautilus Thumbnailer Supporting ArcWelder

After the implementing G2/G3 emulation for gcode2png as part of the G-code thumbnailer, I also added it to G-code viewer yagv fork of mine:

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Print3r

And just for sake of giving a bit of context, adding ArcWelderLib in the pipeline of Print3r via the configuration:

# first declare new post-processor named "arcwelder":
post_arcwelder = ArcWelder %i %o
# optionally, define it to be active (all the time):
post = arcwelder

or optionally enable it on the command-line:

% print3r print cube.stl --post=arcwelder

That’s it for now.

References

• IotaSlicer, OpenGL Z-buffer slicing with multi-color, coded in C++
• OpenGL-STL-Slicer, OpenGL Z-buffer slicing coded in Python
• OpenVDB, Voxel library