Get OpenXR fully up and running

Signed-off-by: Slendi <slendi@socopon.com>

src/Math.cppm

@@ -61,6 +61,9 @@ Vec2<T> operator*(T scalar, Vec2<T> const &v) {
 template <typename T = float>
   requires std::is_arithmetic_v<T>
 struct Rect {
+  Rect(Vec2<T> pos, Vec2<T> size) : pos(pos), size(size) {}
+  Rect(T x, T y, T w, T h) : pos({x, y}), size({w, h}) {}
+
   T &x() { return pos.x; }
   T &y() { return pos.y; }
   T &w() { return size.x; }
@@ -79,8 +82,6 @@ struct Rect {
   T &left() { return x(); }
   T &top() { return y(); }
 
-  Rect(T x, T y, T w, T h) : pos({x, y}), size({w, h}) {}
-
   Vec2<T> pos, size;
 };
 
@@ -190,5 +191,12 @@ std::vector<Math::Rect<T>> subtract_rect(Math::Rect<T> const &src,
   return result;
 }
 
+template <typename T = float>
+  requires std::is_arithmetic_v<T>
+struct Viewport {
+  Rect<T> rect;
+  Vec2<T> depth_limits;
+};
+
 } // namespace Math
 } // namespace LunarWM