appveyor: add Linux build

appveyor.yml

@@ -1,13 +1,25 @@
 version: '{build}'
-image: Visual Studio 2022
+
+# Build on both Windows and Linux
+image:
+  - Visual Studio 2022
+  - Ubuntu2004
 
 # Używamy własnych kroków build
 build: off
 
-# Zmienna z konfiguracją
+# Zmienna z konfiguracją (Windows)
 environment:
   CONFIG: RelWithDebInfo
 
+# Per-image build steps: Windows uses cmd:, Linux uses sh:
+for:
+
+# ------------------------------------------------------------------ Windows
+- matrix:
+    only:
+      - image: Visual Studio 2022
+
   init:
     - cmd: |
         echo Build worker: %APPVEYOR_BUILD_WORKER_IMAGE%
@@ -42,3 +54,36 @@ artifacts:
       name: symbols
     - path: build\bin\%CONFIG%\shaders
       name: shaders
+
+# ------------------------------------------------------------------ Linux
+- matrix:
+    only:
+      - image: Ubuntu2004
+
+  init:
+    - sh: |
+        echo "Build worker: $APPVEYOR_BUILD_WORKER_IMAGE"
+        uname -a
+
+  install:
+    - sh: |
+        git submodule update --init --recursive
+        sudo apt-get update -y
+        sudo apt-get install -y libglfw3-dev python3-dev libpng-dev libopenal-dev libluajit-5.1-dev libserialport-dev libsndfile1-dev
+
+  build_script:
+    - sh: |
+        mkdir -p build
+        cd build
+        cmake .. -DCMAKE_BUILD_TYPE=Release -DWITH_ZMQ=OFF -DWITH_OPENVR=OFF -DUSE_LTO=ON
+        cmake --build . --parallel
+        cd ..
+
+  after_build:
+    - sh: |
+        mkdir -p build/bin/shaders
+        cp -r shaders/. build/bin/shaders/ || true
+
+  artifacts:
+    - path: build/bin
+      name: binaries_linux