From bc27be0f85ac0ec245f5bc2d39aea86187ca742b Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop+git@gmail.com>
Date: Fri, 25 Jun 2010 16:16:08 +0000
Subject: [PATCH] added Ray::randomRay() to generated a ray with origin at
 (0,0,0) and a random direction

git-svn-id: svn://anubis/fart/trunk@254 7f9b0f55-74a9-4bce-be96-3c2cd072584d
---
 main/fart.cc | 10 ++++++++--
 util/Ray.cc  | 17 ++++++++++++++++-
 util/Ray.h   |  1 +
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/main/fart.cc b/main/fart.cc
index cd9b787..3087655 100644
--- a/main/fart.cc
+++ b/main/fart.cc
@@ -1,15 +1,19 @@
 
-#include <iostream>
 #include <string.h>
 #include <unistd.h>                 /* sysconf() */
-#include <stdlib.h>
+#include <stdlib.h>                 /* rand(), srand() */
+#include <time.h>                   /* time() */
 #include <getopt.h>
 #include <sys/time.h>               /* gettimeofday() */
+
+#include <iostream>
 #include <string>
 #include <map>
+
 #include "Scene.h"
 #include "distrib/distrib.h"
 #include "BMP.h"
+
 using namespace std;
 
 void usage(const char * progname)
@@ -163,6 +167,8 @@ int main(int argc, char * argv[])
         usage(argv[0]);
     }
 
+    srand(time(NULL));
+
     const char * filename = argv[optind];
     client_options.push_back(filename);
     Scene scene(scene_options, filename);
diff --git a/util/Ray.cc b/util/Ray.cc
index ebf592c..2eac9f3 100644
--- a/util/Ray.cc
+++ b/util/Ray.cc
@@ -1,6 +1,9 @@
 
+#include <stdlib.h>                 /* rand() */
+
+#include <iostream>
+
 #include "Ray.h"
-#include <iostream>
 
 Ray::Ray()
 {
@@ -13,6 +16,18 @@ Ray::Ray(const Vector & origin, const Vector & direction)
     m_direction.normalize();
 }
 
+Ray Ray::randomRay()
+{
+    double x, y, z;
+    do
+    {
+        x = 2.0 * rand() / RAND_MAX - 1.0;
+        y = 2.0 * rand() / RAND_MAX - 1.0;
+        z = 2.0 * rand() / RAND_MAX - 1.0;
+    } while (x*x + y*y + z*z <= 1.0);
+    return Ray(Vector(0, 0, 0), Vector(x, y, z));
+}
+
 /*
  * return a vector for the point at distance dist
  * from the ray's origin point, along its direction.
diff --git a/util/Ray.h b/util/Ray.h
index 806a359..146d7a9 100644
--- a/util/Ray.h
+++ b/util/Ray.h
@@ -10,6 +10,7 @@ class Ray
     public:
         Ray();
         Ray(const Vector & origin, const Vector & direction);
+        static Ray randomRay();
         const Vector & getOrigin() const { return m_origin; }
         const Vector & getDirection() const { return m_direction; }
         Vector getPositionAt(double dist) const;