36 files changed, 332 insertions, 176 deletions

diff --git a/src/controller/callbacks/mouse_wheel.c b/src/controller/callbacks/mouse_wheel.c
new file mode 100644
index 0000000..52d3c8b
--- a/dev/null
+++ b/src/controller/callbacks/mouse_wheel.c
@@ -0,0 +1,45 @@
+#include "mouse_wheel.h"
+#include "../actions/zoom.h"
+#include <GL/glut.h>
+
+void 
+mouse_wheel (int button, int dir, int x, int y)
+{
+  /*
+   * Get the current coordinates, substract some fixed amount and
+   * then perform the zoom.
+   */
+  GLint viewport[4];
+  glGetIntegerv (GL_VIEWPORT, viewport);
+
+  /*
+   * The step size could be either a fixed number of pixels or a percentage.
+   */
+  //  int step = 5;
+  int step = (viewport[3] - viewport[1]) * 0.10;
+
+  /*
+   * Not that the focus of the zoom is currently the center of the
+   * window but could alternatively be the mouse pointer's position.
+   */
+
+  // Zoom in
+  if (dir > 0)
+    {
+      zoom (step,
+            step,
+            viewport[3] - step,
+                    viewport[3] - step);           
+    }
+
+  // Zoom out
+  else
+    {
+      zoom (-step,
+            -step,
+            viewport[3] + step,
+                    viewport[3] + step);           
+    }
+
+  return;
+}