From 14a7c56abd5362b066e4bde806418a9e4bd716a9 Mon Sep 17 00:00:00 2001
From: Tom Cumming <mail@tomcumming.co.uk>
Date: Tue, 7 Jan 2014 10:54:00 +0000
Subject: [PATCH] Ray plane intersection function

---
 glm/gtx/intersect.hpp |  9 +++++++++
 glm/gtx/intersect.inl | 20 ++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/glm/gtx/intersect.hpp b/glm/gtx/intersect.hpp
index 1ffa872e..3a48bfe1 100644
--- a/glm/gtx/intersect.hpp
+++ b/glm/gtx/intersect.hpp
@@ -52,6 +52,15 @@ namespace glm
 	/// @addtogroup gtx_intersect
 	/// @{
 
+	//! Compute the intersection of a ray and a triangle.
+	//! Ray direction and plane normal must be unit length.
+	//! From GLM_GTX_intersect extension.
+	template <typename genType>
+	bool intersectRayPlane(
+		genType const & orig, genType const & dir,
+		genType const & planeOrig, genType const & planeNormal,
+		typename genType::value_type & intersectionDistance);
+
 	//! Compute the intersection of a ray and a triangle.
 	//! From GLM_GTX_intersect extension.
 	template <typename genType>
diff --git a/glm/gtx/intersect.inl b/glm/gtx/intersect.inl
index cc074d63..0c1cc935 100644
--- a/glm/gtx/intersect.inl
+++ b/glm/gtx/intersect.inl
@@ -13,6 +13,26 @@
 
 namespace glm
 {
+	template <typename genType>
+	GLM_FUNC_QUALIFIER bool intersectRayPlane
+	(
+		genType const & orig, genType const & dir,
+		genType const & planeOrig, genType const & planeNormal,
+		typename genType::value_type & intersectionDistance
+	)
+	{
+		typename genType::value_type d = glm::dot(dir, planeNormal);
+		typename genType::value_type Epsilon = std::numeric_limits<typename genType::value_type>::epsilon();
+
+		if(d < Epsilon)
+		{
+			intersectionDistance = glm::dot(planeOrig - orig, planeNormal) / d;
+			return true;
+		}
+
+		return false;
+	}
+
 	template <typename genType>
 	GLM_FUNC_QUALIFIER bool intersectRayTriangle
 	(