Zoom with wheel only when CTRL is pressed

main.c

@@ -189,15 +189,14 @@ int main(int argc, char **argv)
             } break;
 
             case SDL_MOUSEWHEEL: {
-                if(event.wheel.y > 0)
-                {
-                    user_scale += SCALE_FACTOR * user_scale;
-                }
-                else if(event.wheel.y < 0)
-                {
-                    user_scale -= SCALE_FACTOR * user_scale;
+                if (SDL_GetModState() & KMOD_CTRL) {
+                    if (event.wheel.y > 0) {
+                        user_scale += SCALE_FACTOR * user_scale;
+                    } else if (event.wheel.y < 0) {
+                        user_scale -= SCALE_FACTOR * user_scale;
+                    }
                 }
-            }
+            } break;
 
             default: {}
             }