feat: draw circle

src/main.cpp

@@ -1,7 +1,57 @@
 #include <SDL3/SDL.h>
+#include <SDL3/SDL_events.h>
+#include <SDL3/SDL_render.h>
 #include <cstdio>
 #include <cstdlib>
 
+bool key_event(SDL_Event e) {
+    if (e.type == SDL_EVENT_KEY_DOWN) {
+        if (e.key.key == SDLK_Q) {
+            return true;
+        }
+    }
+    return false;
+}
+
+bool event_handling(SDL_Event e) {
+    while (SDL_PollEvent(&e)) {
+        if (e.type == SDL_EVENT_QUIT) {
+            return true;
+        }
+        if (key_event(e)) {
+            return true;
+        }
+    }
+    return false;
+}
+
+void draw_circle(SDL_Renderer *renderer, int centerX, int centerY, int radius) {
+    int x = radius;
+    int y = 0;
+    int decision = 1 - x;
+
+    SDL_SetRenderDrawColor(renderer, 255, 0, 255, 255);
+    while (x >= y) {
+        SDL_RenderPoint(renderer, centerX + x, centerY + y);
+        SDL_RenderPoint(renderer, centerX - x, centerY + y);
+        SDL_RenderPoint(renderer, centerX + x, centerY - y);
+        SDL_RenderPoint(renderer, centerX - x, centerY - y);
+        SDL_RenderPoint(renderer, centerX + y, centerY + x);
+        SDL_RenderPoint(renderer, centerX - y, centerY + x);
+        SDL_RenderPoint(renderer, centerX + y, centerY - x);
+        SDL_RenderPoint(renderer, centerX - y, centerY - x);
+
+        y++;
+
+        if (decision <= 0) {
+            decision += 2 * y + 1;
+        } else {
+            x--;
+            decision += 2 * (y - x + 1);
+        }
+    }
+}
+
 int main() {
     if (!SDL_Init(SDL_INIT_VIDEO)){ 
         std::printf("SDL_INIT() failed");
@@ -11,7 +61,17 @@ int main() {
     SDL_Window *window;
     window = SDL_CreateWindow("Physics Sim", 720, 540, SDL_WINDOW_RESIZABLE);
 
-    SDL_Delay(5000);
+    SDL_Renderer *renderer = SDL_CreateRenderer(window, NULL);
+
+    SDL_Event e;
+
+    bool exit = false;
+    while (!exit) {
+        exit = event_handling(e);
+        draw_circle(renderer, 150, 150, 100);
+        SDL_RenderPresent(renderer);
+    }
+
     SDL_Quit();
     return 0;
 }