1 files changed, 11 insertions, 2 deletions
diff --git a/src/MathUtil.cpp b/src/MathUtil.cpp
index 3905450..8ea3599 100644
--- a/src/MathUtil.cpp
+++ b/src/MathUtil.cpp
@@ -22,14 +22,23 @@
 
 namespace Zoom {
 
+const float MathUtil::EPSILON = 1E-6;
+
+vmml::vec3f MathUtil::Plane::intersection(const vmml::vec3f &p, const vmml::vec3f &dir) const {
+  float r = (d - p.dot(normal))/dir.dot(normal);
+
+  return p + r*dir;
+}
+
+
 vmml::mat4f MathUtil::perspective(float fovy, float aspect, float zNear) {
   float f = 1/std::tan(fovy*M_PI/360);
 
   vmml::mat4f ret(vmml::mat4f::ZERO);
   ret[0][0] = f/aspect;
   ret[1][1] = f;
-  ret[2][2] = -1;
-  ret[2][3] = -2*zNear;
+  ret[2][2] = EPSILON-1;
+  ret[2][3] = (EPSILON-2)*zNear;
   ret[3][2] = -1;
 
   return ret;