feat: project skeleton, core types and math with transform tests

include/plot/math/vec2.hpp

@@ -0,0 +1,28 @@
+#pragma once
+#include <cmath>
+#include <plot/core/types.hpp>
+
+namespace plot::math {
+
+/// 2D vector of `f32`, used for pixel offsets and normalised device coords.
+struct Vec2 {
+  f32 x = 0.0f;
+  f32 y = 0.0f;
+
+  constexpr Vec2 operator+(const Vec2& o) const noexcept { return {x + o.x, y + o.y}; }
+  constexpr Vec2 operator-(const Vec2& o) const noexcept { return {x - o.x, y - o.y}; }
+  constexpr Vec2 operator*(f32 s) const noexcept { return {x * s, y * s}; }
+  constexpr Vec2 operator/(f32 s) const noexcept { return {x / s, y / s}; }
+
+  constexpr f32 dot(const Vec2& o) const noexcept { return x * o.x + y * o.y; }
+
+  f32 length() const noexcept { return std::sqrt(x * x + y * y); }
+};
+
+constexpr Vec2 operator*(f32 s, const Vec2& v) noexcept { return v * s; }
+
+}  // namespace plot::math
+
+namespace plot {
+using math::Vec2;
+}