gcode-viewer

3D G-code toolpath viewer with interactive GUI and CLI PNG export. Supports .gcode and .bgcode files via gcode-lib.

Features

• Interactive 3D visualization with layer-by-layer slider
• 6 color modes: feature type, height, speed, fan speed, temperature, volumetric flow
• Static PNG export for batch/CI workflows
• 4 camera presets (isometric, top, front, side) + custom azimuth/elevation
• PrusaSlicer TYPE comment parsing for feature-type coloring
• Auto-detected bed dimensions with grid overlay

Installation

Requires Python >= 3.10 and uv.

uv sync

Note: gcode-lib >= 1.1.0 is required. Install it editable if developing locally:

uv pip install -e /path/to/gcode-lib

Usage

Interactive GUI

gcode-viewer model.gcode

Keyboard shortcuts:

CLI Export

# Basic export
gcode-viewer model.gcode --export output.png

# Custom options
gcode-viewer model.gcode -e output.png \
  --camera front \
  --layer 50 \
  --resolution 2560x1440 \
  --color-mode height \
  --show-travel \
  --no-bed

# Custom camera angle
gcode-viewer model.gcode -e output.png \
  --camera-azimuth 45 --camera-elevation 30

CLI Options

Architecture

G-code file
    |
    v
extractor.py  -- gcode-lib parsing --> ToolpathData (layers of Segments)
    |
    v
renderer.py   -- PyVista scene     --> per-layer actors (visibility toggle)
    |
    v
gui.py / cli.py                    --> interactive viewer or PNG export

Key design: one PyVista actor per layer enables fast layer slider updates via visibility toggling — no geometry rebuild needed. Color mode changes recolor cell data in-place.

Testing

# Unit tests (fast, ~2s)
uv run pytest -m "not integration"

# With coverage
uv run pytest -m "not integration" --cov=gcode_viewer --cov-report=term-missing

# Integration tests (requires benchy gcode file, ~12min)
uv run pytest -m integration

# Full suite
uv run pytest --cov=gcode_viewer

Project Structure

src/gcode_viewer/
  __init__.py       # version
  __main__.py       # python -m entry point
  types.py          # ExtrusionType, ColorMode, Segment, LayerData, ToolpathData
  extractor.py      # G-code parsing via gcode-lib
  colors.py         # color palettes, gradients, legend labels
  camera.py         # camera preset calculations
  bed.py            # bed plane, grid, border geometry
  renderer.py       # PyVista scene assembly & recoloring
  gui.py            # interactive viewer (PyVista + Qt)
  cli.py            # argparse + export entry point
tests/
  conftest.py       # shared fixtures
  test_*.py         # unit & integration tests

Dependencies

• gcode-lib — G-code parsing, arc linearization, volume detection
• PyVista — 3D mesh visualization and off-screen rendering
• NumPy — array operations
• PyQt6 — GUI framework