1. Belt tree support could not slice at all.
layer_initialize() hardcodes layer 0's bottom_z to 0, encoding "below layer 0 is
the build plate at z = 0". True for a flat bed; false for a belt, whose virtual
support layers legitimately extend below zero. The bottom-most belt layer
therefore got height = print_z - 0 = -9.8, which reached Flow::with_height() and
threw FlowErrorNegativeFlow.
A 3DBenchy, a mushroom, an L-bracket and an extruded L all failed identically
with negative flow / return -100. Only a bare cube sliced, because its support
never reached that far down.
The bottom is now taken from the previous layer's z, and only a layer 0 whose
print_z is itself negative gets a synthesised bottom below it. Every
non-negative print_z -- every non-belt configuration -- keeps exactly the
previous 0, so this is behaviour-preserving off a belt by construction. An
earlier form used min(0., layer_z(0) - layer_height), which regressed flat beds
whenever the initial layer was thinner than the layer height.
3DBenchy on a 45-degree belt with organic tree support: fails to slice ->
247 support blocks / 168,596 extrusions.
2. Support generated against the belt, and against belt-tilted walls.
A plain 20mm cube on a 45-degree belt generated 86 support blocks and 46,307
support extrusions. Three causes, all gated on the belt floor being active:
a. The build-plate tilt compensation shifted the lower layer the wrong way.
tan(build_plate_tilt_*) carries a magnitude but no direction, and the sign
chosen moved the lower layer away from the newly appearing material rather
than under it, doubling the mismatch. The shift now comes from
belt_floor_shear_factor / belt_floor_from_axis, which carry sign and axis
exactly. Non-belt tilted beds keep the previous behaviour.
b. Material resting on the belt was treated as unsupported. The belt surface
is now unioned into the effective lower layer, sampled at the bottom of the
layer -- a layer meets the belt across its thickness and print_z is the
top. The half-plane is clipped to the layer's bounding box first: unioning
a +/-1000mm half-plane raw with 20mm-scale geometry put a huge dynamic
range through Clipper and left intermittent artefacts every few layers.
c. The object's first slice can be empty on a belt (the bottom vertex is a
sub-extrudable sliver), leaving the layer above with an empty predecessor
even though it rests on the belt. (b) already covers that per island. What
did need fixing is sharp-tail detection, which tests each island against
the raw lower slices; with an empty predecessor that test is trivially true
and every belt-contact island read as a sharp tail. It now tests against
the same effective lower layer.
An earlier form instead skipped the whole layer when the point of
get_extents(curr_polys) -- the bounding box of the union of every island --
nearest the belt was in contact. That was wrong in a way worth recording:
one island resting on the belt could suppress overhang and sharp-tail
detection for a separate island floating well above it. Every decision here
is per-island.
Cube on belt: 46,307 -> 0 support extrusions. Same cube non-belt: 0 before and
after. Benchy on belt still 247 blocks / 168,596 extrusions and a mushroom
111 / 82,157, so false positives are removed without suppressing true ones.
Non-belt is unchanged by measurement, not only by the belt_ovh_active gate:
the same mushroom sliced on a Cartesian printer before and after gives 65,866
support extrusions and 68,717 total extrusions both times, the two G-code
files differing in exactly one line -- the object's plate position.
3. m_anti_overhang was filled and read in different index spaces.
It is consumed in the same index space as m_layer_outlines, where object layer i
lives at num_raft_layers + i, but was filled in object-layer space. Every entry
landed num_raft_layers too low (50 for a 20mm cube at bed Y=50) and the topmost
object layers got none. The belt injection also ran before m_raft_layers was
extended, so it could not have known the offset.
The array is now shifted as a whole and the injection moved after the raft
extension. This also repairs user support blockers under a raft, which is not
belt-specific: it changes behaviour for any ordinary raft, not just the belt's
virtual one, and should be reviewed as a general fix. Measured effect on the
cube was small on its own (46,307 -> 46,334 before the other fixes) because
m_anti_overhang only feeds calculate_placable; kept as a correctness fix on its
own merits.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011jgzj1sf53KMLPweZ8yeUQ
* fix tree support brim
* treesupport3d part 1: more diagnostic logging. (todo once things are fixed: remove this / gate it properly)
* make area under Z=0 in rotated slice pipeline not solid
* fix solid Z=0 layer for belt printers
* fix renderer
* clean up logging
* final review pass
- Add BeltBackTransform class that inverts the shear/scale matrix and
applies it in GCodeWriter::to_machine_coords() so G-code outputs in
the machine's physical coordinate space, gated by new
belt_gcode_back_transform config option
- Extend belt floor clipping to all three tree support pipelines
(Prusa-style, Orca organic, TreeModelVolumes) with per-layer polygon
clipping, anti-overhang integration, and belt raft extension layers
- Fix tree drop_nodes() belt termination, organic support global Z
offset, collision calculation index bug, and first-layer brim/empty
layer checks for belt printers
two-shot - first build built but didn't plumb to UI. Woah.
add pre-slice axis remap, because Y needs to be Z
going to change tactic and move based on bbox min
switch to per axis snapping
per axis swap snap now per object
build plate tilt wasn't invalidating slicer settings
support upper bound now correct, need to get lower bound corrected
axis swapped support termination corrected
Z Shear works with and without pre-slice remap now
- Fix support clipping z-shift calculation by removing coordinate-space
mismatch and sync belt_floor_z_shift with global_z_offset; fix
invalidation so posSupportMaterial no longer resets slicing params
- Add belt floor polygon clipping to non-organic tree support
(slim/strong/hybrid) with collision surface integration in
TreeSupportData, belt extension layers, and first-layer brim
suppression
- Add belt floor clipping to organic tree support pipeline with virtual
belt raft layers, per-layer polygons in TreeModelVolumes, and
post-generation layer trimming; fix pre-existing processing_last_mesh
bug in calculateCollision()
Fix belt floor support clipping: z-shift, invalidation, and global offset
- Fix support clipping z-shift calculation by removing coordinate-space
mismatch (raw_bounding_box min.z vs trafo_centered m_belt_min_z) and
sync belt_floor_z_shift with global_z_offset in global shear mode
- Fix invalidation so posSupportMaterial no longer resets slicing params,
preventing the exact posSlice z-shift from being overwritten by the
bounding-box approximation on support-only setting changes
- Remove double-counting of global z_offset on support layers — support
already inherits the offset from object layers during generation
This Work Was Co-Authored-By Claude Opus 4.6 (1M context) <noreply@anthropic.com>
UI: gray out inactive belt sub-options, rename to mesh transforms, move to Advanced
Fix mesh clipping through build plate after belt shear/scale transform
Generalize G-code viewer designed-view toggle for full belt transform
Clip support layers to transformed belt floor plane
Supports below the tilted build plate (Z = shear_factor * from_axis - min_z)
are now clipped via half-plane intersection after generation. Belt floor
parameters stored in SlicingParameters and populated in both update_slicing_parameters()
and the static slicing_parameters() overload.
Make belt G-code viewer toggle more prominent, add B keyboard shortcut
- Add separator + teal "Belt Printer" header in legend panel
- Append [B] hint to checkbox label
- Add B key shortcut in GLCanvas3D to toggle designed/machine view
- Read belt_printer_angle from loaded G-code headers to enable belt view
Add per-axis global transform option for belt printer shear
New belt_shear_{x,y,z}_global bool configs. When enabled, shear incorporates
instance shift so objects at different bed positions get position-aware
transform (Z += factor * instance_shift_on_from_axis).
Fix global shear: use layer Z offset instead of mesh transform, add config invalidation
- Global shear offset applied as post-slicing layer print_z adjustment
instead of mesh transform (which was absorbed by min_z normalization
or shifted mesh out of slice range)
- Register all belt transform options in Print::invalidate_state_by_config_options
to trigger posSlice re-slicing (the fallback only invalidated Print steps,
not PrintObject steps — belt changes had no effect without manual re-slice)
- Belt gcode remap options added to steps_gcode (gcode-export only)
- Skip empty-first-layer check for belt objects with global Z offset
WIP: split instances for global shear, relative Z offsets, debug logging
- PrintApply: when belt global mode active, prevent instance grouping by
adding unique Z perturbation to trafo — each copy becomes its own
PrintObject with independent layers
- PrintObjectSlice: compute global Z offset relative to minimum Y shift
across all PrintObjects (lowest-Y object stays at Z=0)
- Debug logging (warning level) for belt global shift values and offsets
Known issues:
- Cached posSlice results cause stale offsets when mixing copies with
individually-added objects — need to compute min baseline outside slice()
- Supports still generate to Z=0 instead of object's global Z offset
Fix global shear for copied objects: disable shared-object layer optimization
When belt global Z shear is active, each object needs unique layer Z
values based on its bed position. The shared-object optimization was
causing copies to reuse the source object's layers (and its Z offset)
instead of computing their own position-based offset.
started work on getting supports to work properly
one step forward, one step back
this version didn't quite work. Getting somewhere though
about to add UI controllable tests
added configuration options for supports
tweak CLAUDE.md to be more aggressive for my machine. This commit should probably be pulled out before contributing upstream
still chasing down some bugs
moving objects between slices no longer results in improper Z-height because of caching
added more data to the debug logs
Z offset is getting more global again
still not quite there, I think there's a fundamental logic flaw?
hunting for bugs
finally have a functional fix
Add belt floor clipping to tree supports (organic and non-organic)
- Add belt floor polygon clipping to non-organic tree support
(slim/strong/hybrid) in draw_circles() and terminate nodes at the
belt surface instead of the horizontal build plate
- Add belt floor clipping to organic tree support pipeline with virtual
belt raft layers for sub-floor branch generation, per-layer belt
floor polygons in TreeModelVolumes, and post-generation layer trimming
- Fix pre-existing processing_last_mesh bug in TreeModelVolumes that
prevented m_anti_overhang (support blockers) from ever being applied;
skip empty first layer check for belt printers
Commits:
current approach: make a face surface to build supports to
closer!
supports now terminate on shear plane, now need to get shear plane to correct Z height
nearly there
chasing down logic issues still
committing for checkpoint, this still does not work
still got logic problems...
cull support clipping
stashing changes for now. Going to focus on getting the global shear OFF support generation dialed first.
beginning per object shear calcs
Local shear transform is on correct Z offset now
local shear finally works now and needs more testing
global shear works now, needs thorough testing
debugging non-45 degree angles
debugging part 2
supports at all angles work now
remove debug logging
Add belt floor collision to non-organic tree support pipeline
- Integrate belt floor as a collision surface in TreeSupportData so
branches route around the belt naturally, replacing the explicit
termination checks in drop_nodes()
- Add belt extension layers below the object after draw_circles() to
allow support geometry to extend to the diagonal belt surface instead
of terminating at a horizontal first layer
- Fix coordinate overflow in belt floor polygons (scale_(1e4) exceeds
int32), skip first-layer brim expansion for belt printers, and
extend empty first layer check bypass to all belt modes
add debug logging, Z translate for tree supports
still not seeing any cutoff surface yet
adding debug options
attempt #2 at trees
if hit Z buildplate stop but don't set to_buildplate true
getting closer
tree support almost there, just need to get rid of the circles at the beginning
getting closer
belt / shear plane clip works, need to figure out the buidlplate plane issues
more logic, added debugging logs
supports now extend somewhat below Z=0 in global shear mode
fix bad alloc, add 10mm below build plate
fully works now
shear transform + prusa tree support generation works now.
pull out debug logging
* Initial port of organic tree support from PrusaSlicer
* Port missing Organic support parameters from PrusaSlicer
* Update parameter naming
* Reorganize the `raft_first_layer_expansion` and `raft_first_layer_density` parameters as they are not only used by rafts
* Reset support style only in simple mode
* Sync latest update from PrusaSlicer & copyrights
* Fix organic tree support crash with invalid parameters
---------
Co-authored-by: Vojtech Bubnik <bubnikv@gmail.com>
