From 0c7cbeaa6c998994112047b39889bc96b9629fc3 Mon Sep 17 00:00:00 2001
From: Sara <sara@saragerretsen.nl>
Date: Sun, 26 Jan 2025 21:13:25 +0100
Subject: [PATCH] feat: added reflect

---
 src/core/math/vector.cpp | 5 +++++
 src/core/math/vector.hpp | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/src/core/math/vector.cpp b/src/core/math/vector.cpp
index fbd4c2f..bd4e1b0 100644
--- a/src/core/math/vector.cpp
+++ b/src/core/math/vector.cpp
@@ -39,6 +39,11 @@ Vecf Vecf::move_towards(Vecf const &from, Vecf const &to, float delta) {
     return Vecf::lerp(from, to, delta / Vecf::distance(from, to));
 }
 
+Vecf Vecf::reflect(Vecf const &in, Vecf const &normal) {
+    Vecf const midpoint{normal * Vecf::dot(normal, in)};
+    return (midpoint - in) + midpoint;
+}
+
 float Vecf::magnitude() const {
     return std::sqrt(this->x * this->x + this->y * this->y);
 }
diff --git a/src/core/math/vector.hpp b/src/core/math/vector.hpp
index 13f5db6..eef8e1c 100644
--- a/src/core/math/vector.hpp
+++ b/src/core/math/vector.hpp
@@ -22,6 +22,8 @@ struct Vecf {
     static Vecf lerp(Vecf const &from, Vecf const &to, float t);
     //! move towards a point by a set unit distance
     static Vecf move_towards(Vecf const &from, Vecf const &to, float delta);
+    //! calculate the outgoing velocity of an object reflecting against a surface
+    static Vecf reflect(Vecf const &in, Vecf const &normal);
     //! magnitude (a.k.a length or absolute) of this vector
     float magnitude() const;
     //! square of the magnitude, use for comparing lengths of vectors efficiently