feat: canvasengine singleton

src/core/canvas_engine.cpp

@@ -1,9 +1,11 @@
 #include "canvas_engine.hpp"
+#include <cassert>
 #include <SDL2/SDL_error.h>
 #include <SDL2/SDL_events.h>
 #include <SDL2/SDL_keyboard.h>
 #include <SDL2/SDL_log.h>
 #include <SDL2/SDL_render.h>
+#include <SDL2/SDL_image.h>
 
 
 #ifndef PROJECTNAME
@@ -11,6 +13,8 @@
 #endif
 
 namespace ce {
+CanvasEngine *CanvasEngine::singleton_instance{nullptr};
+
 CanvasEngine::CanvasEngine() {
     if(SDL_Init(SDL_INIT_EVERYTHING) != 0) {
         SDL_LogError(SDL_LOG_CATEGORY_ERROR, "Failed to initialize SDL, SDL error: %s", SDL_GetError());
@@ -39,6 +43,9 @@ CanvasEngine::~CanvasEngine() {
 }
 
 void CanvasEngine::run() {
+    assert(CanvasEngine::singleton_instance == nullptr && "Engine singleton instance already assigned, starting another instance is invalid");
+    // register as singleton
+    CanvasEngine::singleton_instance = this;
     // start tracking time
     std::timespec_get(&this->startup_ts, TIME_UTC);
     this->frame_start_ts = this->last_frame_start_ts = this->startup_ts;
@@ -57,6 +64,8 @@ void CanvasEngine::run() {
             this->last_frame_start_ts = this->frame_start_ts;
         }
     }
+    assert(CanvasEngine::singleton_instance == this && "Engine singleton instance changed while game was running");
+    CanvasEngine::singleton_instance = nullptr;
 }
 
 void CanvasEngine::request_close() {
@@ -86,7 +95,7 @@ void CanvasEngine::process_event(SDL_Event const &evt) {
     }
 }
 
-void CanvasEngine::tick(double delta_time) {
+void CanvasEngine::tick(double delta_time [[maybe_unused]]) {
 }
 
 void CanvasEngine::draw(SDL_Renderer *render) {

src/core/canvas_engine.hpp

@@ -1,14 +1,26 @@
 #ifndef CANVAS_ENGINE_HPP
 #define CANVAS_ENGINE_HPP
 
+#include "node.hpp"
+#include <ctime>
+#include <cassert>
 #include <SDL2/SDL.h>
 #include <SDL2/SDL_events.h>
 #include <SDL2/SDL_render.h>
-#include <ctime>
+#include <memory>
+
+#if __has_cpp_attribute(gnu::always_inline)
+#define forceinline [[gnu::always_inline]] inline
+#elif __has_cpp_attribute(clang::always_inline)
+#define forceinline [[clang::always_inline]] inline
+#else
+#define forceinline inline
+#endif
 
 namespace ce {
 class CanvasEngine {
 private:
+    static CanvasEngine *singleton_instance; //!< currently active engine instance
     SDL_Window *window{nullptr}; //!< primary application window
     SDL_Renderer *render{nullptr}; //!< primary application window's renderer
     std::timespec startup_ts{}; //!< time in UTC at start of application (when run() was called)
@@ -20,7 +32,11 @@ private:
 public:
     CanvasEngine();
     ~CanvasEngine();
-
+    forceinline CanvasEngine *get_singleton(){
+        assert(CanvasEngine::singleton_instance && "Engine singleton instance not assigned yet, call run() before attempting to access");
+        return CanvasEngine::singleton_instance;
+    }
+    void setup(std::unique_ptr<Node> scene_root);
     void run();
     void request_close();
     void set_target_delta_time(double target);