skp2blend - a CLI tool which runs on linux and converts .skp files to .blend and/or .obj

.github/workflows/docker.yml

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+name: Build and push Docker image
+
+on:
+  push:
+    branches: [skp2blend]
+    paths:
+      - "skp2blend/**"
+      - ".github/workflows/docker.yml"
+  workflow_dispatch:
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}/skp2blend
+  SDK_RELEASE_URL: https://github.com/RedHaloStudio/Sketchup_Importer/releases/download/0.27.0/sketchup_importer-0.27.zip
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Download SketchUp SDK from upstream release
+        run: |
+          wget -qO /tmp/sdk.zip "$SDK_RELEASE_URL"
+          unzip -q /tmp/sdk.zip -d /tmp/sdk
+
+          # Place DLLs where the Dockerfile expects them
+          mkdir -p skp2blend/sketchup_sdk/binaries/sketchup/x64
+          cp /tmp/sdk/sketchup_importer/SketchUpAPI.dll \
+             /tmp/sdk/sketchup_importer/SketchUpCommonPreferences.dll \
+             skp2blend/sketchup_sdk/binaries/sketchup/x64/
+
+          # Place the Python 3.11 compiled extension
+          cp /tmp/sdk/sketchup_importer/sketchup.cp311-win_amd64.pyd \
+             skp2blend/sketchup.pyd
+
+          rm -rf /tmp/sdk /tmp/sdk.zip
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract Docker metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          tags: |
+            type=sha,prefix=
+            type=raw,value=latest
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v6
+        with:
+          context: skp2blend
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}

skp2blend/.dockerignore

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+__pycache__
+*.pyc

skp2blend/Dockerfile

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+# ===========================================================================
+# Two-stage SKP-to-Blend converter — Docker image
+#
+# Build-time prerequisites (not redistributable — user must supply):
+#   sketchup_sdk/   SketchUp C SDK for Windows x64
+#     binaries/sketchup/x64/SketchUpAPI.dll   (+ companion DLLs)
+#   sketchup.pyd    Compiled Cython extension for Windows Python 3.11 x64
+#                   (built via: python setup.py build_ext --inplace)
+#
+# Build:
+#   docker build -t skp2blend .
+#
+# Run:
+#   docker run --rm -v /path/to/files:/data skp2blend /data/model.skp /data/model.blend
+# ===========================================================================
+
+FROM scottyhardy/docker-wine:stable-11.0
+
+USER root
+ENV DEBIAN_FRONTEND=noninteractive
+
+# ── Extra packages not in the base image ─────────────────────────────────
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+        unzip xz-utils \
+        libxi6 libxrender1 libxfixes3 libglib2.0-0 libxkbcommon0 \
+        libgl1 libsm6 \
+    && rm -rf /var/lib/apt/lists/*
+
+# ── Wine prefix init ────────────────────────────────────────────────────
+ENV WINEDEBUG=-all
+ENV WINEPREFIX=/root/.wine
+ENV WINEARCH=win64
+
+RUN xvfb-run -a wine wineboot --init && wineserver -w
+
+# ── Windows Python 3.11 (embeddable) ───────────────────────────────────
+RUN wget -qO /tmp/python-embed.zip \
+        "https://www.python.org/ftp/python/3.11.9/python-3.11.9-embed-amd64.zip" && \
+    mkdir -p "${WINEPREFIX}/drive_c/Python311" && \
+    cd "${WINEPREFIX}/drive_c/Python311" && \
+    unzip /tmp/python-embed.zip && \
+    rm /tmp/python-embed.zip
+
+# Enable import of .py files next to the embedded Python
+RUN sed -i 's/^#import site/import site/' \
+    "${WINEPREFIX}/drive_c/Python311/python311._pth"
+
+# ── SketchUp SDK + compiled extension ──────────────────────────────────
+COPY sketchup_sdk/binaries/sketchup/x64/*.dll "${WINEPREFIX}/drive_c/Python311/"
+COPY sketchup.pyd "${WINEPREFIX}/drive_c/Python311/"
+
+# ── Blender (headless) ─────────────────────────────────────────────────
+ARG BLENDER_VERSION=5.0.1
+ARG BLENDER_URL=https://download.blender.org/release/Blender5.0/blender-5.0.1-linux-x64.tar.xz
+RUN wget -qO /tmp/blender.tar.xz "${BLENDER_URL}" && \
+    mkdir -p /opt/blender && \
+    tar -xf /tmp/blender.tar.xz -C /opt/blender --strip-components=1 && \
+    rm /tmp/blender.tar.xz && \
+    ln -s /opt/blender/blender /usr/local/bin/blender
+
+# ── Converter scripts ──────────────────────────────────────────────────
+COPY intermediate.py skputil.py skp_extractor.py blend_builder.py obj_builder.py \
+     render_preview.py cli.py \
+     /opt/skp2blend/
+
+# Also copy the Python modules into the Wine Python directory so the
+# extractor can import them
+RUN cp /opt/skp2blend/intermediate.py /opt/skp2blend/skputil.py \
+       "${WINEPREFIX}/drive_c/Python311/"
+
+ENV PATH="/opt/skp2blend:${PATH}"
+
+ENTRYPOINT ["python3", "/opt/skp2blend/cli.py", \
+            "--blender", "/usr/local/bin/blender", \
+            "--wine-python", "C:\\Python311\\python.exe"]

skp2blend/Makefile

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+#! make
+
+build:
+	docker build -t skp2blend .

skp2blend/README.md

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+# skp2blend
+
+Convert SketchUp `.skp` files to Blender `.blend` (and optionally Wavefront `.obj`) on Linux amd64 — no SketchUp installation required.
+
+## Motivation
+
+The SketchUp C SDK and its Python bindings (`sketchup.pyd`) are Windows-only. This makes batch-converting `.skp` files on Linux servers or CI pipelines impossible without a Windows machine. skp2blend solves this by packaging everything into a single Docker image:
+
+- **Wine** runs the Windows Python interpreter and SketchUp SDK to read `.skp` files
+- **Blender headless** builds the `.blend` output with full material, texture, camera, and hierarchy support
+- **Pure-Python OBJ export** provides a lightweight alternative output format with no Blender dependency
+
+The result is a self-contained CLI tool that runs on any Linux amd64 host with Docker.
+
+## Quick start
+
+```bash
+# Using the convenience wrapper (builds/pulls the Docker image as "skp2blend")
+./convert.sh model.skp model.blend
+
+# Produce both .blend and .obj
+./convert.sh model.skp model.blend --also-obj
+
+# OBJ only (faster — skips Blender entirely)
+./convert.sh model.skp model.blend --obj-only
+```
+
+Or run the Docker image directly:
+
+```bash
+docker run --rm \
+    -v "$(pwd):/data" \
+    skp2blend \
+    /data/model.skp /data/model.blend
+```
+
+## How it works
+
+Conversion runs in two stages:
+
+1. **Stage 1 — Extract** (`skp_extractor.py`, runs under Wine)
+   Reads the `.skp` file via the SketchUp C SDK and writes a portable `intermediate.json` plus extracted texture files to a work directory.
+
+2. **Stage 2 — Build .blend** (`blend_builder.py`, runs inside Blender headless)
+   Reads `intermediate.json` and constructs the Blender scene: materials with Principled BSDF nodes, UV-mapped textures, cameras, the full group/component hierarchy, and deduplicated instancing for repeated components.
+
+3. **Stage 2b — Build .obj** (`obj_builder.py`, pure Python, optional)
+   Reads the same `intermediate.json`, flattens the entity tree into world-space geometry, and writes `.obj` + `.mtl` files with texture references. Useful for side-by-side comparison with the `.blend` output or as an archival format.
+
+## CLI options
+
+| Flag | Description |
+|---|---|
+| `--scene NAME` | Import a specific named SketchUp scene (applies layer visibility and camera) |
+| `--max-instance N` | Instancing threshold — components appearing N+ times are deduplicated (default: 1) |
+| `--clip-end F` | Camera far clip plane in meters (default: 250.0) |
+| `--preview` | Render a 1920×1080 PNG preview image next to the output `.blend` |
+| `--also-obj` | Also produce a `.obj` file alongside the `.blend` |
+| `--obj-only` | Only produce `.obj` output, skip Blender |
+| `--keep-work-dir` | Retain the intermediate work directory after conversion |
+| `--work-dir PATH` | Use a specific work directory instead of a temporary one |
+
+## Using the GHCR image
+
+Pre-built images are published to GHCR by CI on every push to the `skp2blend` branch:
+
+```bash
+docker run --rm \
+    -v "$(pwd):/data" \
+    ghcr.io/recraft-ou/sketchup_importer/skp2blend:latest \
+    /data/model.skp /data/model.blend --preview
+```
+
+### GPU-accelerated rendering
+
+Pass your GPU to the container for faster EEVEE preview renders. Without a GPU, Blender falls back to software rendering (works but slower).
+
+**NVIDIA** (requires [NVIDIA Container Toolkit](https://docs.nvidia.com/datacenter/cloud-native/container-toolkit/install-guide.html)):
+
+```bash
+docker run --rm --gpus all \
+    -v "$(pwd):/data" \
+    ghcr.io/recraft-ou/sketchup_importer/skp2blend:latest \
+    /data/model.skp /data/model.blend --preview
+```
+
+**AMD / Intel** (Mesa/RADV — pass the DRI render nodes):
+
+```bash
+docker run --rm --device /dev/dri \
+    -v "$(pwd):/data" \
+    ghcr.io/recraft-ou/sketchup_importer/skp2blend:latest \
+    /data/model.skp /data/model.blend --preview
+```
+
+## Building the Docker image
+
+The image requires the SketchUp C SDK DLLs and a compiled `sketchup.pyd`, which are not included in this repository. They can be obtained from the [upstream release](https://github.com/RedHaloStudio/Sketchup_Importer/releases/tag/0.27.0):
+
+```bash
+# Download and extract the SDK artifacts
+wget -qO /tmp/sdk.zip \
+    https://github.com/RedHaloStudio/Sketchup_Importer/releases/download/0.27.0/sketchup_importer-0.27.zip
+unzip -q /tmp/sdk.zip -d /tmp/sdk
+
+# Place them where the Dockerfile expects
+mkdir -p sketchup_sdk/binaries/sketchup/x64
+cp /tmp/sdk/sketchup_importer/SketchUpAPI.dll \
+   /tmp/sdk/sketchup_importer/SketchUpCommonPreferences.dll \
+   sketchup_sdk/binaries/sketchup/x64/
+cp /tmp/sdk/sketchup_importer/sketchup.cp311-win_amd64.pyd sketchup.pyd
+
+# Build
+docker build -t skp2blend .
+```
+
+A GitHub Actions workflow (`.github/workflows/docker.yml`) automates this and pushes the image to GHCR on every push to the `skp2blend` branch.
+
+## Output formats
+
+### .blend
+
+Full-fidelity Blender scene with:
+- Principled BSDF materials with packed textures
+- UV mapping
+- Group/component hierarchy preserved as Blender parent-child relationships
+- Named cameras from SketchUp scenes
+- VERTS-based instancing for repeated components
+- Negative-scale correction for mirrored components
+
+### .obj + .mtl
+
+Flat geometry suitable for interchange and archival:
+- All transforms baked into world-space vertex positions
+- Z-up to Y-up coordinate conversion (OBJ convention)
+- Material colors, opacity, and texture map references in `.mtl`
+- Texture files copied to a `textures/` directory alongside the `.obj`
+- No hierarchy, cameras, or instancing (OBJ limitation)
+
+## Exit codes
+
+| Code | Meaning |
+|---|---|
+| 0 | Success |
+| 1 | Bad input (missing file, bad arguments) |
+| 2 | Stage 1 failure (extractor) |
+| 3 | Stage 2 or 2b failure (builder) |