Changelog

Name: Preview3D
Price: 9.99 USD
Author: xfanta

What's new in Preview3D, release by release.

v1.2.0

LatestAugust 2026

The toolpath is coloured by what it's printing — perimeters, infill, bridges, supports — using your slicer's own palette, with a legend to match.
A layer slider peels the print open, so you can look inside at any height.
Extrusions are drawn at their real width, lit and rounded like laid-down plastic, instead of hairlines.
Feature types are read from PrusaSlicer, Slic3r, OrcaSlicer, Bambu Studio and Cura.

G2/G3 arcs are now followed properly. PrusaSlicer's arc fitting emits fitted curves as single arc moves, which were being flattened to straight chords — crossing brim loops over each other and cutting corners off round parts.
The G-code window's title bar carries the app branding like every other window.

Same release on Mac and iPad — the G-code viewer lives in the shared kit.
Large prints stay interactive: past ~800k drawn segments the toolpath falls back to hairlines rather than dropping frames.

iPadAugust 2026

First iPadOS release — a native viewer for the same formats, included in the universal purchase.
Place a model in the room with AR — sized to about 20 cm, whatever units the file uses.
Quick Look previews and thumbnails in the Files app, including STEP, painted 3MF, FBX and G-code.
Touch orbit, background picker and the model info panel.

PMI / GD&T reading, the assembly tree and format conversion remain Mac-only; iPad hands off USDZ and PNG.

G-codeJuly 2026

Open a slicer's G-code or PrusaSlicer .bgcode directly: orbit the print toolpath in 3D, switch to the embedded preview image, and read the print stats — time, filament, weight, layer height and material.
Quick Look previews and Finder thumbnails cover .gcode and .bgcode as well.

First releaseJuly 2026

Native macOS viewer (SceneKit / Metal) for STEP/STP, STL, OBJ, PLY, glTF/GLB, USDZ/USD, DAE, FBX, 3DS and 3MF.
STEP read via StepKit - a pure-Swift B-rep kernel with watertight tessellation and crease-aware normals.
STEP per-part colors (STYLED_ITEM / COLOUR_RGB) rendered - colored assemblies show in their real colors.
Painted multi-material 3MF (PrusaSlicer mmu_segmentation) rendered in its filament colors, including sub-facet brush detail.
Turntable / arcball orbit, configurable background and optional floor.

Info panel with volume, surface area, centre of mass, watertightness, bounding-box dimensions and source unit for STEP.
B-rep structure (solids / faces / edges) and triangle / vertex counts.
Instanced assembly tree of sub-parts - repeated parts are placed at their true positions and share geometry; click a part to highlight and isolate it.
Centre-of-mass marker you can toggle on in the view.

Semantic PMI in the info panel: dimensions with ± tolerance bands, geometric tolerances (flatness, position, perpendicularity, profile…) with zones and datum references, and datum features.
Graphical PMI overlay - dimension lines, leaders and symbols drawn over the model, toggleable.

Quick Look previews for every supported format - including STEP, painted 3MF, FBX and 3DS that macOS can't render on its own.
Finder thumbnails via a dedicated thumbnail extension.
File-type association, Quick Look and thumbnails now cover the mesh formats read via Assimp (FBX, 3DS, X3D, LWO, MS3D, AC, AMF, OFF…), not just the core formats.
Heavy STEP previews and thumbnails use a fast coarse/decimated load, so large CAD stays quick in Finder.

One-click convert: STEP → STL / OBJ / GLB / USDZ (StepKit), any loaded scene → STL / OBJ / PLY (Model I/O).
USDZ output is ready for AR Quick Look.
Export a single selected sub-part of an assembly on its own.
PNG snapshots of the current view at 1×, 2× and 4×.