From 2ed39ad4eb9ebf64768dbf4aeefafc5ebb072ca7 Mon Sep 17 00:00:00 2001
From: Keuin <keuinx@gmail.com>
Date: Fri, 15 Apr 2022 11:11:08 +0800
Subject: Add vec3::is_zero and vec3::reflect. (not tested)

---
 vec.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

(limited to 'vec.h')

diff --git a/vec.h b/vec.h
index 8efbc9a..64eaaca 100644
--- a/vec.h
+++ b/vec.h
@@ -35,6 +35,12 @@ struct vec3 {
         return vec3{0, 0, 0};
     }
 
+    bool is_zero() const {
+#define EPS (1e-8)
+        return x >= -EPS && y >= -EPS && z >= -EPS && x <= EPS && y <= EPS && z <= EPS;
+#undef EPS
+    }
+
     vec3 operator+(const vec3 &b) const {
         return vec3{.x=x + b.x, .y=y + b.y, .z=z + b.z};
     }
@@ -80,6 +86,12 @@ struct vec3 {
     vec3 unit_vec() const {
         return *this * (1.0 / norm());
     }
+
+    // Get the reflected vector. Current vector is the incoming vector, n is the normal vector (length should be 1).
+    vec3 reflect(const vec3 &n) const {
+        assert(fabs(n.mod2() - 1.0) < 1e-8);
+        return *this - 2.0 * dot(*this, n) * n;
+    }
 };
 
 // print to ostream
-- 
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