(main)+zoom in and out by keyboard,+translation by mouse

main.c

@@ -58,6 +58,28 @@ int main(void)
   while (!WindowShouldClose())
   {
     step(&state);
+
+    if (IsKeyPressed(KEY_UP) || IsKeyDown(KEY_UP))
+    {
+      Vector2 world_pos = GetScreenToWorld2D(GetMousePosition(), camera);
+      camera.offset     = GetMousePosition();
+      camera.target     = world_pos;
+      camera.zoom += 0.125f;
+    }
+    if (IsKeyPressed(KEY_DOWN) || IsKeyDown(KEY_DOWN))
+    {
+      Vector2 world_pos = GetScreenToWorld2D(GetMousePosition(), camera);
+      camera.offset     = GetMousePosition();
+      camera.target     = world_pos;
+      camera.zoom -= 0.125f;
+    }
+
+    if (IsMouseButtonDown(MOUSE_BUTTON_LEFT))
+    {
+      Vector2 delta = Vector2Scale(GetMouseDelta(), -1.0f / camera.zoom);
+      camera.target = Vector2Add(camera.target, delta);
+    }
+
     BeginDrawing();
     ClearBackground(BLACK);
     BeginMode2D(camera);