migrat a SDL3

source/defines.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include "SDL3/SDL.h"
+#include <stdlib.h>
+
+constexpr char WINDOW_CAPTION[] = "demo3_pixels_bouncing";
+constexpr int WIDTH = 320;
+constexpr int HEIGHT = 240;
+constexpr int ZOOM = 3;
+constexpr float GRAVITY = 0.2f;
+constexpr int DOT_SIZE = 1;
+constexpr int MAX_DOTS = 200000;
+constexpr int TEXT_TIME = 100;
+
+struct Color
+{
+    int r, g, b;
+};