The Cartesian designed-view preview over-extended the toolpaths past the model
shell by a height-proportional amount (up to ~20mm tall parts), most visibly on
long multi-part prints; compact parts like a calibration cube looked fine.
Two coupled causes:
- Belt start G-code that primes with a Z advance and a 'G92 Z0' reset leaves a
constant machine-Z origin in the GCodeProcessor, so move positions are stored as
gcode_Z + origin. The linear back-transform mixes that constant with the
gantry-Y term, leaving a per-move designed-Y error that min-corner anchoring
cannot cancel when an elevated move (e.g. a bridge) happens to cancel it at the
bbox minimum. Expose GCodeProcessorResult::belt_z_origin (the m_origin[Z] left by
the start G-code) and subtract it before the back-transform.
- Elevated features (bridges/overhangs) are mis-mapped by the linear inverse to
outside the model body; build the anchor bbox only from moves within model_bb +/-
10mm, with a fallback to the full bbox when the clip would drop the bulk (object
placed away from the belt entry) so the gross-offset case still anchors.
Preview-only; G-code output is unchanged.
The belt designed (upright) preview back-transforms the machine-frame G-code
into model space with the linear belt inverse. That inverse recovers the
print's shape and orientation, but not the per-object placement/lift
translation: the object's position on the belt, the BeltSliceStrategy min-Z
lift, and the centering pre-translate are applied OUTSIDE
build_forward_transform() (see PrintObjectSlice.cpp), so its linear inverse
cannot undo them. The result was a constant offset (~20 mm on the belt-advance
axis) of the toolpaths from the model shell, on every model.
Recover the missing translation generally — independent of the offset's exact
source or the axis remap — by anchoring the back-transformed object body
(extrusions on layer_id >= 1, i.e. excluding the layer-0 prime/skirt) onto the
upright model bounding box, the same space the shells render in, and folding
that translation into the belt inverse before converting to libvgcode.
Replaces the previous Y=0 anchoring in LibVGCodeWrapper, which pinned the
toolpaths to the belt entry rather than to the model and so left the offset in
place for any object not sitting at the origin.
On a belt printer the emitted G-code is in the machine frame (45-deg sheared,
axis-remapped, scaled), so the toolpath preview shows the print as a sheared
slab floating off the bed. Map each toolpath vertex back to model/Cartesian
space for the "designed" view.
The back-transform is the inverse of the full G-code forward pipeline
(BeltGCodeWriter::to_machine_coords):
model = [BeltForward^-1 if !gcode_back_transform] . AxisRemap^-1 . MachineFrame^-1
built from config, so it handles any rotation / shear / scale / axis-remap
combination, not just plain 45-deg belt slicing. Computed in load_as_gcode()
from print.config() and applied per-vertex inside libvgcode::convert (display
position only; layer_id, times and the volumetric/flow math keep the raw
machine values, so the layer slider and stats are unaffected).
- Toggle with the existing "Show designed view" checkbox / hotkey B; off shows
the raw machine-frame G-code (useful for debugging the transform itself).
Defaults to on.
- Belt printers skip the same-result-id load cache so the upright view applies
and the toggle takes effect even when the G-code is unchanged.
- The object extrusions (layer_id >= 1) are anchored to the belt entry to drop
the constant machine-origin offset (start-G-code belt advance) that the linear
back-transform alone does not capture; start-G-code prime lines are excluded
so they don't steal the anchor.
Physical max-volumetric-speed test (belt #62 v4 asset) on the IR3 V2 with eSUN
PLA white: the wall stayed clean up to ~100 mm/s = ~20 mm3/s before
under-extrusion. The shipped cap of 10 mm3/s was ~half the real ceiling and
was silently throttling infill.
- eSUN PLA @IdeaFormer IR3 V2: filament_max_volumetric_speed 10 -> 20
- 0.20mm Standard @IdeaFormer IR3 V2: sparse_infill_speed 200 (~18 mm3/s at the
new cap, no longer throttled). Outer wall (45), PA (0.12), accel (1000)
unchanged — accuracy preserved.
- IdeaFormer.json version bump for profile-cache refresh.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The original PR skipped the max-print-height check entirely on belt printers
because the sliced (virtual) Z is belt travel, not build height. As the reviewer
noted, that removed the only working height guard. Restore a correct guard:
- Print::validate: on belt printers, compare the upright object height
(max over instances of the scene-space bbox) against printable_height directly.
printable_height is the usable VERTICAL clearance above the belt: the gantry
travels up the tilted plane (reach = height/cos(tilt)) and its axis range is
sized for that (IR3 V2: ~354 mm gantry travel = 250 mm vertical at 45deg, and
printable_height = 250). Hardware-confirmed 250 mm vertical clearance, so no
cos(tilt) factor is applied.
- BuildVolume::set_belt_printer: drop the diagonal Z scaling; the build-volume Z
already equals printable_height, keeping the live 'outside build volume'
highlight in agreement with validate().
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Tommaso Bianchi