From 34a8729811a69d0ac93f543cd8ee2dbbcaa45b98 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop+hg@gmail.com>
Date: Wed, 8 Dec 2010 13:03:38 -0500
Subject: [PATCH] Spin: replaced 6 orthogonal directions with a completely
 random axis

---
 modes/Spin.cc | 28 ++++++++++++----------------
 modes/Spin.h  |  4 ++--
 2 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/modes/Spin.cc b/modes/Spin.cc
index 56af375..3b86fb8 100644
--- a/modes/Spin.cc
+++ b/modes/Spin.cc
@@ -1,16 +1,13 @@
 
 #include <stdlib.h>
 #include <time.h>
+#include <math.h>
 
 #include <GL/gl.h>
 #include <GL/glu.h>
 
 #include "Spin.h"
 
-static const float directions[][3] = {
-    {0, 0, 1}, {0, 0, -1}, {0, 1, 0}, {0, -1, 0}, {1, 0, 0}, {-1, 0, 0}
-};
-
 Spin::Spin()
 {
     m_num_monitors = 1;
@@ -34,7 +31,7 @@ bool Spin::expose (GnomeScreensaver & gs)
         if (gs.getTicks() - m_monitor_info[i].last_switch_ticks
                 > m_monitor_info[i].switch_time)
         {
-            m_monitor_info[i].direction = getRandomDirection();
+            getRandomAxis(&m_monitor_info[i].axis);
             m_monitor_info[i].switch_time = getRandomSwitchTime();
             m_monitor_info[i].last_switch_ticks = gs.getTicks();
         }
@@ -49,11 +46,10 @@ bool Spin::expose (GnomeScreensaver & gs)
 
         glLoadMatrixf(&m_monitor_info[monitor_num].rotation[0]);
 
-        int direction = m_monitor_info[monitor_num].direction;
         glRotatef((gs.getTicks() - m_last_ticks) / 1000.0 * 360.0 / 4.0,
-                directions[direction][0],
-                directions[direction][1],
-                directions[direction][2]);
+                m_monitor_info[monitor_num].axis[0],
+                m_monitor_info[monitor_num].axis[1],
+                m_monitor_info[monitor_num].axis[2]);
         glGetFloatv(GL_MODELVIEW_MATRIX,
                 &m_monitor_info[monitor_num].rotation[0]);
 
@@ -92,20 +88,20 @@ void Spin::initMonitorInfo()
 {
     for (int i = 0; i < m_num_monitors; i++)
     {
-        m_monitor_info[i].direction = getRandomDirection();
+        getRandomAxis(&m_monitor_info[i].axis);
         glGetFloatv(GL_MODELVIEW_MATRIX, &m_monitor_info[i].rotation[0]);
         m_monitor_info[i].switch_time = getRandomSwitchTime();
         m_monitor_info[i].last_switch_ticks = 0;
     }
 }
 
-int Spin::getRandomDirection()
+void Spin::getRandomAxis(float (*axis)[3])
 {
-    int direction = (int) (rand() / (double)RAND_MAX *
-            sizeof(directions) / sizeof(directions[0]));
-    if (direction >= sizeof(directions) / sizeof(directions[0]))
-        direction = 0;
-    return direction;
+    double alpha = rand() / (double)RAND_MAX * 2.0 * M_PI;
+    double beta = rand() / (double)RAND_MAX * M_PI;
+    (*axis)[0] = cos(alpha) * sin(beta);
+    (*axis)[1] = sin(alpha) * sin(beta);
+    (*axis)[2] = cos(beta);
 }
 
 uint32_t Spin::getRandomSwitchTime()
diff --git a/modes/Spin.h b/modes/Spin.h
index cc47eb4..82ac1a1 100644
--- a/modes/Spin.h
+++ b/modes/Spin.h
@@ -16,7 +16,7 @@ class Spin : public Mode
         bool update (GnomeScreensaver & gs);
         typedef struct monitor_info_s
         {
-            int direction;
+            float axis[3];
             float rotation[16];
             int switch_time;
             uint32_t last_switch_ticks;
@@ -27,7 +27,7 @@ class Spin : public Mode
         monitor_info_t *m_monitor_info;
         unsigned int m_last_ticks;
         void initMonitorInfo();
-        int getRandomDirection();
+        void getRandomAxis(float (*axis)[3]);
         uint32_t getRandomSwitchTime();
 };