Enable building of the chapters.

* Enables Linux (Vulkan, OpenGL)
* Enables Android (Vulkan, OpenGLES)

.github/workflows/build-android.yml

@@ -0,0 +1,30 @@
+name: 'Android Build Chapters'
+on:  
+  pull_request:
+    branches: [ "main" ]  
+#     tags:
+#       - "v*.*.*"
+#   workflow_dispatch:
+
+jobs:
+  build:
+    name: Android Build
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: true
+      matrix:
+        os: [ubuntu-latest]
+        target: [android]
+        graphics: [VULKAN, OPENGL_ES]    
+        chapter: [Chapter1, Chapter2, Chapter3, Chapter4, Chapter5]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Build ${{ matrix.chapter }} using ${{ matrix.gfx }} on ${{ matrix.os }}
+        run: |
+          echo "Building ${{ matrix.chapter }} using ${{ matrix.gfx }} on ${{ matrix.os }} ${{ github.ref_name }}"
+          export GFX=${{ matrix.graphics }}
+          cd ${{ matrix.chapter }}
+          chmod 755 gradlew
+          ./gradlew assembleDebug
+

.github/workflows/build-host-linux.yml

@@ -0,0 +1,39 @@
+name: 'Linux Build Chapters'
+on:  
+  pull_request:
+    branches: [ "main" ]  
+#     tags:
+#       - "v*.*.*"
+#   workflow_dispatch:
+
+jobs:
+  build:
+    name: Linux Build
+    runs-on: ${{matrix.os}}
+    strategy:
+      fail-fast: true
+      matrix:
+        os: [ubuntu-latest]
+        target: [linux]
+        graphics: [VULKAN, OPENGL]
+    steps:
+      - name: Setup
+        run: |
+          sudo apt-get install libglu1-mesa-dev freeglut3-dev mesa-common-dev libgl1-mesa-dev
+          sudo apt install vulkan-tools
+          sudo apt install libvulkan-dev
+          sudo apt install vulkan-validationlayers-dev spirv-tools glslang-tools 
+          sudo apt install libxrandr-dev libxxf86vm-dev
+          sudo apt-get install libxcb-randr0-dev libxcb-xtest0-dev libxcb-xinerama0-dev libxcb-shape0-dev libxcb-xkb-dev
+          sudo apt-get install libgl1-mesa-dev libvulkan-dev libx11-xcb-dev libxcb-dri2-0-dev libxcb-glx0-dev libxcb-icccm4-dev libxcb-keysyms1-dev libxcb-randr0-dev libxrandr-dev libxxf86vm-dev mesa-common-dev
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Build ${{ matrix.gfx }} on ${{ matrix.os }}
+        run: |
+          echo "Building ${{ matrix.os }} ${{ github.ref_name }}"          
+          export GFX=${{ matrix.graphics }}
+          mkdir build
+          cd build
+          cmake ..
+          cmake --build .
+

.github/workflows/build-host-windows.yml

@@ -0,0 +1,30 @@
+name: 'Windows Build Chapters'
+on:  
+  pull_request:
+    branches: [ "main" ]  
+#     tags:
+#       - "v*.*.*"
+#   workflow_dispatch:
+
+jobs:
+  build:
+    if: false
+    name: Windows Build
+    runs-on: ${{matrix.os}}
+    strategy:
+      fail-fast: true
+      matrix:
+        os: [windows-latest]
+        target: [windows]
+        graphics: [VULKAN, OPENGL, DX11, DX12]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Build ${{ matrix.gfx }} on ${{ matrix.os }}
+        run: |
+          echo "Building ${{ matrix.os }} ${{ github.ref_name }}"          
+          set GFX=${{ matrix.graphics }}
+          mkdir build
+          cd build
+          cmake ..
+          cmake --build .

cmake/graphics_api_select.cmake

@@ -4,13 +4,12 @@
 
 include_guard()
 
+
 set(XR_TUTORIAL_GRAPHICS_API "VULKAN" CACHE STRING "Which graphics API to use when building the tutorial projects.")
-if(WIN32)
-    set_property(CACHE XR_TUTORIAL_GRAPHICS_API PROPERTY STRINGS D3D11 D3D12 OPENGL VULKAN)
-elseif(LINUX AND NOT ANDROID)
-    set_property(CACHE XR_TUTORIAL_GRAPHICS_API PROPERTY STRINGS OPENGL VULKAN)
-elseif(ANDROID)
-    set_property(CACHE XR_TUTORIAL_GRAPHICS_API PROPERTY STRINGS OPENGL_ES VULKAN)
+
+IF(DEFINED ENV{GFX})
+    message(STATUS, "Overriding graphics api: " $ENV{GFX} )
+    set_property(CACHE XR_TUTORIAL_GRAPHICS_API PROPERTY VALUE $ENV{GFX})
 endif()
 
 function(AddGraphicsAPIDefine PROJECT_NAME)