Added ray-plane intersection.

plane.cpp

@@ -0,0 +1,20 @@
+#include <cmath>
+
+#include "plane.hpp"
+
+#define TOL 1e-6
+
+using std::abs;
+using glm::dot;
+
+bool Plane::intersect(Ray & r, float & t, vec3 & n) const {
+  float d = dot(r.m_direction, m_normal);
+
+  if (abs(d) > TOL) {
+    t = dot(m_normal, (m_point - r.m_origin)) / d;
+    n = vec3(m_normal);
+    return t >= 0.0f;
+  }
+
+   return false;
+}