Add Github Action for Windows and fix build

.github/workflows/windows.yaml

@@ -0,0 +1,48 @@
+name: Windows
+on:
+  pull_request:
+
+jobs:
+  build:
+    name: Window CI
+    env:
+      PACKAGE: gz-rendering9
+    runs-on: windows-latest
+    steps:
+    - name: setup-pixi
+      uses: prefix-dev/setup-pixi@v0.8.1
+      with:
+        run-install: false
+
+    - name: Install build tools
+      run: |
+        pixi init
+        pixi add vcstool colcon-common-extensions pkgconfig
+    - name: Setup pixi env variables
+      shell: bash
+      run: |
+        eval "$(pixi shell-hook)"
+        echo CMAKE_PREFIX_PATH=$CONDA_PREFIX/Library >> $GITHUB_ENV
+    - name: Install base dependencies
+      run: |
+        # List adapted from https://github.com/gazebo-tooling/release-tools/blob/f89ac8cafc646260598eb8eb6d94be8093bdc9f7/jenkins-scripts/lib/windows_env_vars.bat#L22
+        pixi add assimp dlfcn-win32 eigen ffmpeg freeimage gdal gflags ogre ogre-next spdlog tinyxml2
+    - name: Clone source dependencies
+      run: |
+        mkdir src
+        cd src
+        pixi run vcs import --input https://raw.githubusercontent.com/gazebo-tooling/gazebodistro/master/${env:PACKAGE}.yaml
+
+    - uses: actions/checkout@v4
+      with:
+        path: src/gz-rendering
+
+    - name: Build Dependencies
+      run: |
+        pixi run colcon build --merge-install --cmake-args -G"Visual Studio 17 2022" -A x64 -DCMAKE_BUILD_TYPE=Release -DBUILD_TESTING=OFF  --event-handlers console_direct+ --packages-up-to ${env:PACKAGE}
+
+    - name: Build Package
+      run: pixi run colcon build --merge-install --cmake-args -G"Visual Studio 17 2022" -A x64 -DCMAKE_BUILD_TYPE=Release -DBUILD_TESTING=ON -DSKIP_ogre=ON --event-handlers console_direct+ --packages-select ${env:PACKAGE}
+
+    - name: Test
+      run: pixi run colcon test --merge-install --event-handlers console_direct+ --packages-select ${env:PACKAGE}

ogre2/src/Ogre2Scene.cc

@@ -20,10 +20,14 @@
   #include <OpenGL/gl.h>
   #include <OpenGL/glext.h>
 #else
-#ifndef _WIN32
+  #ifdef _WIN32
+    // windows.h has to be included *before* GL/gl.h
+    // to avoid redefinition errors.
+    #include <windows.h>
+  #endif
+
   #include <GL/gl.h>
 #endif
-#endif
 
 #include <gz/common/Console.hh>