add an imgui demo app + cmake cleanup

src/CMakeLists.txt

@@ -1,23 +1,22 @@
+set(DP_WARN_FLAGS -Wall -Wextra -Wpedantic)
+
 # Source: log.c by rxi (https://github.com/rxi/log.c)
 add_library(logc log.c)
 target_compile_features(logc PRIVATE c_std_11)
 target_compile_definitions(logc PRIVATE -DLOG_USE_COLOR)
-target_compile_options(logc INTERFACE "-ffile-prefix-map=${CMAKE_SOURCE_DIR}=." PRIVATE "-Wall" "-Wextra")
+target_compile_options(logc INTERFACE -ffile-prefix-map=${CMAKE_SOURCE_DIR}=. PRIVATE ${DP_WARN_FLAGS})
 
 find_package(Threads)
 
-
 add_library(dp_common dp_common.c)
 target_compile_features(dp_common PRIVATE c_std_11)
-target_compile_options(dp_common PUBLIC "-Wall" "-Wextra")
+target_compile_options(dp_common PUBLIC ${DP_WARN_FLAGS}) # spread warning flags
 target_link_libraries(dp_common
     PUBLIC logc
     PUBLIC nng
     PUBLIC Threads::Threads
 )
 
-find_package(SDL2 REQUIRED)
-
 add_executable(doompanning doompanning.cc)
 target_compile_features(doompanning PRIVATE cxx_std_17)
 target_link_libraries(doompanning
@@ -25,8 +24,15 @@ target_link_libraries(doompanning
     PRIVATE imgui
     )
 
+add_executable(dp_imgui_demo dp_imgui_demo.cc)
+target_compile_features(dp_imgui_demo PRIVATE cxx_std_17)
+target_link_libraries(dp_imgui_demo
+    PRIVATE dp_common
+    PRIVATE imgui
+    )
+
 add_executable(doomsim doomsim.cc)
 target_compile_features(doomsim PRIVATE cxx_std_17)
 target_link_libraries(doomsim
     PRIVATE dp_common
-)
+)

src/dp_imgui_demo.cc

@@ -0,0 +1,77 @@
+#include <imgui.h>
+#include <backends/imgui_impl_sdl.h>
+#include <backends/imgui_impl_sdlrenderer.h>
+#include <SDL.h>
+
+#include "dp_common.h"
+
+void dp_sdl_fatal(const char *const msg)
+{
+    log_fatal("%s: %s", msg, SDL_GetError());
+    abort();
+}
+
+int main(int argc, char *argv[])
+{
+    (void) argc;
+    (void) argv;
+
+    if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER))
+        dp_sdl_fatal("SDL_Init");
+
+#ifdef SDL_HINT_IME_SHOW_UI
+    SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1");
+#endif
+
+    const auto windowFlags = SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI;
+    auto window = SDL_CreateWindow("doompanning imgui demo", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, windowFlags);
+    if (!window)
+        dp_sdl_fatal("SDL_CreateWindow");
+
+    auto renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_PRESENTVSYNC | SDL_RENDERER_ACCELERATED);
+
+    if (!renderer)
+        dp_sdl_fatal("SDL_CreateRenderer");
+
+    IMGUI_CHECKVERSION();
+    ImGui::CreateContext();
+    ImGui::StyleColorsDark();
+    ImGui_ImplSDL2_InitForSDLRenderer(window, renderer);
+    ImGui_ImplSDLRenderer_Init(renderer);
+
+    bool show_demo_window = true;
+    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
+
+    bool done = false;
+
+    while (!done)
+    {
+        SDL_Event event;
+        while (SDL_PollEvent(&event))
+        {
+            ImGui_ImplSDL2_ProcessEvent(&event);
+
+            if (event.type == SDL_QUIT)
+                done = true;
+            if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
+                done = true;
+        }
+
+        // Start the Dear ImGui frame
+        ImGui_ImplSDLRenderer_NewFrame();
+        ImGui_ImplSDL2_NewFrame();
+        ImGui::NewFrame();
+
+        if (show_demo_window)
+            ImGui::ShowDemoWindow(&show_demo_window);
+
+        // Rendering
+        ImGui::Render();
+        SDL_SetRenderDrawColor(renderer, (Uint8)(clear_color.x * 255), (Uint8)(clear_color.y * 255), (Uint8)(clear_color.z * 255), (Uint8)(clear_color.w * 255));
+        SDL_RenderClear(renderer);
+        ImGui_ImplSDLRenderer_RenderDrawData(ImGui::GetDrawData());
+        SDL_RenderPresent(renderer);
+    }
+
+    return 0;
+}