1 files changed, 149 insertions, 0 deletions
diff --git a/vec3.h b/vec3.h
new file mode 100644
index 0000000..d81a1a1
--- /dev/null
+++ b/vec3.h
@@ -0,0 +1,149 @@
+#ifndef VEC3_H
+#define VEC3_H
+
+#include <cmath>
+#include <iostream>
+
+using std::sqrt;
+
+struct vec3 {
+  public:
+    double e[3];
+
+    constexpr vec3() : e{0,0,0} {}
+    constexpr vec3(double e0, double e1, double e2) : e{e0, e1, e2} {}
+
+    constexpr double x() const { return e[0]; }
+    constexpr double y() const { return e[1]; }
+    constexpr double z() const { return e[2]; }
+    double& x() { return e[0]; }
+    double& y() { return e[1]; }
+    double& z() { return e[2]; }
+
+    constexpr vec3 operator-() const { return vec3(-e[0], -e[1], -e[2]); }
+    constexpr double operator[](int i) const { return e[i]; }
+    constexpr double& operator[](int i) { return e[i]; }
+
+    constexpr vec3& operator+=(const vec3& v) {
+        e[0] += v.e[0];
+        e[1] += v.e[1];
+        e[2] += v.e[2];
+        return *this;
+    }
+
+    constexpr vec3& operator*=(double t) {
+        e[0] *= t;
+        e[1] *= t;
+        e[2] *= t;
+        return *this;
+    }
+
+    constexpr vec3& operator/=(double t) {
+        return *this *= 1/t;
+    }
+
+    constexpr vec3 operator+(const vec3& v) const {
+        return vec3(e[0] + v.e[0], e[1] + v.e[1], e[2] + v.e[2]);
+    }
+    
+    constexpr vec3 operator-(const vec3& v) const {
+        return vec3(e[0] - v.e[0], e[1] - v.e[1], e[2] - v.e[2]);
+    }
+    
+    constexpr vec3 operator*(const vec3& v) const {
+        return vec3(e[0] * v.e[0], e[1] * v.e[1], e[2] * v.e[2]);
+    }
+    
+    constexpr vec3 operator*(double t) const {
+        return vec3(t*e[0], t*e[1], t*e[2]);
+    }
+
+    constexpr vec3 operator/(double t) const {
+        t = 1 / t;
+        return vec3(t*e[0], t*e[1], t*e[2]);
+    }
+    
+    constexpr double length() const {
+        return sqrt(length_squared());
+    }
+
+    constexpr double length_squared() const {
+        return e[0]*e[0] + e[1]*e[1] + e[2]*e[2];
+    }
+
+    constexpr vec3 normalize() const {
+        auto v = *this;
+        v /= length();
+        return v;
+    }
+
+    constexpr double dot(const vec3& v) const {
+        return e[0] * v.e[0] + e[1] * v.e[1] + e[2] * v.e[2];
+    }
+
+    constexpr vec3 reflect(vec3 v) const {
+        v *= -2 * dot(v);
+        v += *this;
+        return v;
+    }
+
+    constexpr vec3 refract(vec3 v, double etaietat) const {
+        auto inv = -(*this);
+        auto cos_theta = std::min(inv.dot(v), 1.0);
+        auto rperp = (*this + v * cos_theta) * etaietat;
+        auto rpara = v * -std::sqrt(std::fabs(1.0 - rperp.length_squared()));
+        return rperp + rpara;
+    }
+
+    static vec3 random() {
+        return vec3(randomN(), randomN(), randomN());
+    }
+
+    //static vec3 random(double min, double max) {
+    //    return vec3(randomN(min,max), randomN(min,max), randomN(min,max));
+    //}
+};
+
+// point3 is just an alias for vec3, but useful for geometric clarity in the code.
+using point3 = vec3;
+
+
+// Vector Utility Functions
+
+inline std::ostream& operator<<(std::ostream& out, const vec3& v) {
+    return out << v.e[0] << ' ' << v.e[1] << ' ' << v.e[2];
+}
+
+constexpr inline vec3 operator*(double t, const vec3& v) {
+    return v * t;
+}
+    
+constexpr inline vec3 operator/(double t, const vec3& v) {
+    return v * (1 / t);
+}
+
+
+inline constexpr vec3 cross(const vec3& u, const vec3& v) {
+    return vec3(u.e[1] * v.e[2] - u.e[2] * v.e[1],
+                u.e[2] * v.e[0] - u.e[0] * v.e[2],
+                u.e[0] * v.e[1] - u.e[1] * v.e[0]);
+}
+
+inline constexpr vec3 unit_vector(const vec3& v) {
+    return v / v.length();
+}
+
+inline vec3 randomUnitSphere() {
+    for (;;) {
+        if (auto p = vec3::random() * 2 - vec3(1, 1, 1); p.length_squared() < 1)
+            return p;
+    }
+}
+
+inline vec3 randomHemisphere(const vec3& normal) {
+    vec3 unit = randomUnitSphere().normalize();
+    return unit.dot(normal) > 0 ? unit : -unit;
+}
+
+#endif
+