7 files changed, 149 insertions, 44 deletions

diff --git a/src/controller/mousewheel.c b/src/controller/mousewheel.c
new file mode 100644
index 0000000..c9ac742
--- a/dev/null
+++ b/src/controller/mousewheel.c
@@ -0,0 +1,45 @@
+#include "mousewheel.h"
+#include "performzoom.h"
+#include <GL/glut.h>
+
+void 
+mousewheel (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)
+    {
+      performzoom (step,
+                   step,
+                   viewport[3] - step,
+                           viewport[3] - step);            
+    }
+
+  // Zoom out
+  else
+    {
+      performzoom (-step,
+                   -step,
+                   viewport[3] + step,
+                           viewport[3] + step);            
+    }
+
+  return;
+}