Index: Games/Pingus/src/pingu_action.cxx
===================================================================
RCS file: /usr/local/cvsroot/Games/Pingus/src/pingu_action.cxx,v
retrieving revision 1.8
diff -u -r1.8 pingu_action.cxx
--- Games/Pingus/src/pingu_action.cxx	16 Sep 2002 20:31:09 -0000	1.8
+++ Games/Pingus/src/pingu_action.cxx	13 Oct 2002 17:58:17 -0000
@@ -18,7 +18,9 @@
 //  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
 #include <assert.h>
+#include <math.h>
 #include "col_map.hxx"
+#include "force_vector.hxx"
 #include "world.hxx"
 #include "pingu.hxx"
 #include "pingu_action.hxx"
@@ -82,6 +84,117 @@
     return true;
 
   return false;
+}
+
+void
+PinguAction::move_with_forces (float x_to_add, float y_to_add)
+{
+  Vector force_to_apply = pingu->get_velocity();
+
+  // Add any additional forces that are required
+  force_to_apply.x += x_to_add;
+  force_to_apply.y += y_to_add;
+
+  // Put the force together with any existing forces, including gravity
+  pingu->set_velocity( ForcesHolder::apply_forces(pingu->get_pos(),
+						  force_to_apply) );
+
+  Vector resultant_force = pingu->get_velocity();
+
+  // Strictly speaking x_numerator should be initialised with
+  // (resultant_force.y / 2) and y_numerator with (resultant_force.x / 2).
+  // This would make the algorithm essentially match the Mid-Point Line
+  // Algorithm.  However, zero should do and is more comprehendable.
+  int x_numerator = 0;
+  int y_numerator = 0;
+  int denominator = 0;
+  int x_inc = 0;
+  int y_inc = 0;
+
+  if (fabs(resultant_force.x) > fabs(resultant_force.y))
+    {
+      // Initialise so that we move in whole pixels in x direction and
+      // 'fractions' of a pixel in y direction.
+      denominator = static_cast<int>(fabs(resultant_force.x));
+      x_inc = denominator;
+      y_inc = static_cast<int>(fabs(resultant_force.y));
+    }
+  else
+    {
+      // Initialise so that we move in whole pixels in y direction and
+      // 'fractions' of a pixel in x direction.
+      denominator = static_cast<int>(fabs(resultant_force.y));
+      x_inc = static_cast<int>(fabs(resultant_force.x));
+      y_inc = denominator;
+    }
+
+  // Keep moving the Pingu until there is only a fraction left
+  while (resultant_force.x <= -1 || resultant_force.x >= 1
+	  || resultant_force.y <= -1 || resultant_force.y >= 1)
+    {
+      x_numerator += x_inc;
+
+      // Is it now not a fraction?
+      if (x_numerator >= denominator)
+	{
+	  // Revert back to being a fraction
+	  x_numerator -= denominator;
+
+	  // Move the Pingu depending on what the direction of the force is
+	  if (resultant_force.x >= 1)
+	    {
+	      // Check what is to the right of the Pingu
+	      if (rel_getpixel(pingu->direction, 0) != Groundtype::GP_NOTHING
+		    || head_collision_on_walk(pingu->direction, 0))
+		{
+		  break;
+		}
+
+	      pingu->set_x(pingu->get_x() + 1);
+	      resultant_force.x--;
+	    }
+	  else if (resultant_force.x <= -1)
+	    {
+	      // Check what is to the left of the Pingu
+	      if (rel_getpixel(-(pingu->direction), 0) != Groundtype::GP_NOTHING
+		    || head_collision_on_walk(-(pingu->direction), 0) )
+		{
+		  break;
+		}
+
+	      pingu->set_x(pingu->get_x() - 1);
+	      resultant_force.x++;
+	    }
+	}
+
+      y_numerator += y_inc;
+
+      // Is it now not a fraction?
+      if (y_numerator >= denominator)
+	{
+	  // Revert back to being a fraction
+	  y_numerator -= denominator;
+
+	  // Move the Pingu depending on what the direction of the force is
+	  if (resultant_force.y >= 1)
+	    {
+	      if (rel_getpixel(0, -1) != Groundtype::GP_NOTHING)
+		break;
+
+	      pingu->set_y(pingu->get_y() + 1);
+	      resultant_force.y--;
+	    }
+	  else if (resultant_force.y <= -1)
+	    {
+	      if (head_collision_on_walk(0, 1))
+		break;
+
+	      pingu->set_y(pingu->get_y() - 1);
+	      resultant_force.y++;
+	    }
+	}
+    }
+
 }
 
 /* EOF */