27 files changed, 179 insertions, 549 deletions

diff --git a/src/controller/callbacks/mouse.c b/src/controller/callbacks/mouse.c
index 16e8b8b..f594c23 100644
--- a/src/controller/callbacks/mouse.c
+++ b/src/controller/callbacks/mouse.c
@@ -9,6 +9,7 @@
 #include "reshape.h"
 #include <GL/glut.h>
 #include <math.h>
+#include <stdio.h>
 #include <stdlib.h>
 
 /*
@@ -19,8 +20,12 @@
 void
 mouse (int button, int state, int x, int y)
 {
+  // Release left button.
   if (button == GLUT_LEFT_BUTTON && state == GLUT_UP)
     {
+      // Deactive a panning event if one was happening.
+      S.pan.active = false;
+
       if (S.selection.active && S.selection.purpose == ZOOM)
         {
           /*
@@ -41,7 +46,9 @@ mouse (int button, int state, int x, int y)
       /*
        * Complete a selection if one was started and not cancelled.
        */
-      if (S.selection.active && S.selection.purpose == SET)
+      if (S.selection.active && 
+          S.selection.purpose == SET &&
+          glutGetModifiers () == GLUT_ACTIVE_CTRL)
         {
 
           /*
@@ -116,12 +123,31 @@ mouse (int button, int state, int x, int y)
 
     }
 
-  if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
+  // Begin selection.
+  if (button == GLUT_LEFT_BUTTON && 
+      state == GLUT_DOWN && 
+      glutGetModifiers () == GLUT_ACTIVE_CTRL)
     {
       S.selection.active = true;
       S.selection.x = x;
       S.selection.y = y;
     }
 
+  // Pan.
+  if (button == GLUT_LEFT_BUTTON &&
+      state == GLUT_DOWN &&
+      glutGetModifiers () != GLUT_ACTIVE_CTRL)
+    {
+      /*
+       * Detection of the first point in a panning event.
+       */
+      if (S.pan.active == false)
+        {
+          S.pan.active = true;
+          S.pan.begin[0] = x;
+          S.pan.begin[1] = y;
+        }
+    }
+
   return;
 }