Made it more clear that the values being compared are floats

src/events/SDL_mouse.c

@@ -545,7 +545,7 @@ SDL_SendMouseWheel(SDL_Window * window, SDL_MouseID mouseID, float x, float y, S
         SDL_SetMouseFocus(window);
     }
 
-    if (x == 0. && y == 0.) {
+    if (x == 0.0f && y == 0.0f) {
         return 0;
     }