Build docs (#49)

* add CMake files for building the documentation
* dynamically generate PNG files from SGVs
* add workflow for building the documentation
* rename original opengx PDF file. This is to make it clear that it's from 2012.

Author: mardy

.github/workflows/docs.yml

@@ -0,0 +1,37 @@
+name: Documentation
+
+on:
+  push:
+    paths:
+      - 'doc/**'
+  pull_request:
+    paths:
+      - 'doc/**'
+
+jobs:
+  docs:
+    name: ubuntu-latest
+    runs-on: ubuntu-latest
+ 
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Install dependencies
+      run: |
+        sudo apt update
+        sudo apt install -y \
+          cmake \
+          imagemagick \
+          texlive-latex-extra
+
+    - name: Build
+      run: |
+        cmake -S. -Bbuild -DBUILD_DOCS=ON -DBUILD_OPENGX=OFF
+        cd build
+        make 
+
+    - name: Archive built documentation
+      uses: actions/upload-artifact@v4
+      with:
+        name: opengx.pdf
+        path: build/doc/src/opengx.pdf

CMakeLists.txt

@@ -1,9 +1,18 @@
 cmake_minimum_required(VERSION 3.13)
 project(OpenGX VERSION 0.1)
 
+option(BUILD_OPENGX "Build the opengx library" ON)
+option(BUILD_DOCS "Build the documentation" OFF)
+
 set(CMAKE_C_STANDARD 11)
 set(CMAKE_CXX_STANDARD 17)
 
+set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake" "${CMAKE_MODULE_PATH}")
+
+# This is ON by default, of course, but we allow switching it off in case one
+# just needs to build the documentation
+if(BUILD_OPENGX)
+
 set(TARGET opengx)
 
 include(GNUInstallDirs)
@@ -43,3 +52,10 @@ install(FILES ${CMAKE_CURRENT_BINARY_DIR}/opengl.pc
         DESTINATION "${CMAKE_INSTALL_LIBDIR}/pkgconfig")
 install(FILES OpenGLConfig.cmake
         DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/OpenGL")
+
+endif(BUILD_OPENGX)
+
+if(BUILD_DOCS)
+    include(UseLATEX)
+    add_subdirectory(doc/src)
+endif()