xo-imgui: + example ex4a. resize working on ubuntu (ex4 broken tho)

xo-imgui/example/CMakeLists.txt

@@ -2,3 +2,4 @@ add_subdirectory(ex1)
 add_subdirectory(ex2)
 add_subdirectory(ex3)
 add_subdirectory(ex4)
+add_subdirectory(ex4a)

xo-imgui/example/ex4a/CMakeLists.txt

@@ -0,0 +1,74 @@
+if (XO_ENABLE_EXAMPLES)
+    # imgui dependency
+
+    if (XO_ENABLE_VULKAN)
+
+        find_path(
+            IMGUI_INCLUDE_DIR
+            NAMES imgui/imgui.h
+            DOC "path to imgui header"
+            HINTS ${PROJECT_SOURCE_DIR}/include
+        )
+        if (IMGUI_INCLUDE_DIR)
+            message(STATUS "found imgui/imgui.h in IMGUI_INCLUDE_DIR=[${IMGUI_INCLUDE_DIR}]")
+        else()
+            message(FATAL_ERROR "unable to find imgui.h")
+        endif()
+
+        # target executable
+
+        set(SELF_EXE imgui_ex4a)
+        add_executable(${SELF_EXE} imgui_ex4a.cpp
+                    ${IMGUI_INCLUDE_DIR}/imgui/imgui.cpp
+                    ${IMGUI_INCLUDE_DIR}/imgui/imgui_demo.cpp
+                    ${IMGUI_INCLUDE_DIR}/imgui/imgui_draw.cpp
+                    ${IMGUI_INCLUDE_DIR}/imgui/imgui_widgets.cpp
+                    ${IMGUI_INCLUDE_DIR}/imgui/imgui_tables.cpp
+                    ${IMGUI_INCLUDE_DIR}/imgui/backends/imgui_impl_sdl2.cpp
+                    #${IMGUI_INCLUDE_DIR}/imgui/backends/imgui_impl_opengl3.cpp
+                    #${IMGUI_INCLUDE_DIR}/imgui/backends/imgui_impl_glfw.cpp
+                    ${IMGUI_INCLUDE_DIR}/imgui/backends/imgui_impl_vulkan.cpp
+        )
+        xo_include_options2(${SELF_EXE})
+
+        # OpenGL dependency
+
+        # have to choose between
+        #   libGL.so
+        # or
+        #   libOpenGL.so + libGLX.so    # GLVND = OpenGL Vendor Neutral Dispatch (e.g. mesa|nvda)
+        #
+        # expect in .build/CMakeCache.txt:
+        #   OPENGL_opengl_LIBRARY:FILEPATH=/path/to/libOpenGL.so
+        #   OpenGL_DIR:PATH=OpenGL_DIR-NOTFOUND  # no cmake config file
+
+        #    set(OpenGL_GL_PREFERENCE GLVND)  # or LEGACY
+        #    find_package(OpenGL REQUIRED)  # find_package(OpenGL CONFIG REQUIRE) won't work
+        #    target_link_libraries(${SELF_EXE} PUBLIC OpenGL::GL)
+
+        find_package(Vulkan REQUIRED)
+        target_link_libraries(${SELF_EXE} PUBLIC Vulkan::Vulkan)
+
+        # GLEW dependency
+        xo_external_pkgconfig_dependency(${SELF_EXE} GLEW glew)
+
+        # GLFW dependency
+        #find_package(glfw3 CONFIG REQUIRED)
+        #target_link_libraries(${SELF_EXE} PUBLIC glfw) # want -lglfw
+
+        # SDL2 dependency
+        xo_external_pkgconfig_dependency(${SELF_EXE} SDL2 sdl2)
+
+        # would prefer to use just IMGUI_INCLUDE_DIR,
+        # but imgui/backends/ .h files don't quote the imgui/ stem
+        #
+        target_include_directories(${SELF_EXE} PUBLIC ${IMGUI_INCLUDE_DIR}/imgui)
+
+        xo_dependency(${SELF_EXE} xo_object)
+        xo_dependency(${SELF_EXE} randomgen)
+        xo_dependency(${SELF_EXE} xo_flatstring)
+        xo_dependency(${SELF_EXE} xo_alloc)
+
+        install(TARGETS ${SELF_EXE} DESTINATION ${XO_EXAMPLE_INSTALL_DIR})
+    endif()
+endif()