--- /dev/null
+// $Id: path.hpp 3114 2006-03-23 23:47:04Z sommer $
+//
+// SuperTux Path
+// Copyright (C) 2005 Philipp <balinor@pnxs.de>
+// Copyright (C) 2006 Christoph Sommer <christoph.sommer@2006.expires.deltadevelopment.de>
+// Copyright (C) 2006 Matthias Braun <matze@braunis.de>
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+// 02111-1307, USA.
+#include <config.h>
+
+#include <math.h>
+#include "path_walker.hpp"
+
+PathWalker::PathWalker(const Path* path)
+ : path(path), current_node_nr(0), next_node_nr(0), node_time(0),
+ walking_speed(1.0)
+{
+ last_pos = path->nodes[0].position;
+ node_time = path->nodes[0].time;
+}
+
+PathWalker::~PathWalker()
+{
+}
+
+Vector
+PathWalker::advance(float elapsed_time)
+{
+ assert(elapsed_time >= 0);
+
+ elapsed_time *= fabsf(walking_speed);
+
+ const Path::Node* current_node = & (path->nodes[current_node_nr]);
+ while(node_time - elapsed_time < 0) {
+ elapsed_time -= current_node->time - node_time;
+
+ if(walking_speed > 0) {
+ advance_node();
+ } else if(walking_speed < 0) {
+ goback_node();
+ }
+
+ current_node = & (path->nodes[current_node_nr]);
+ if(walking_speed > 0) {
+ node_time = current_node->time;
+ } else {
+ node_time = path->nodes[next_node_nr].time;
+ }
+ }
+
+ const Path::Node* next_node = & (path->nodes[next_node_nr]);
+ node_time -= elapsed_time;
+
+ Vector new_pos = current_node->position +
+ (next_node->position - current_node->position)
+ * (1 - (node_time / current_node->time));
+
+ Vector result = new_pos - last_pos;
+ last_pos = new_pos;
+
+ return result;
+}
+
+void
+PathWalker::advance_node()
+{
+ current_node_nr = next_node_nr;
+
+ if(next_node_nr + 1 < path->nodes.size()) {
+ next_node_nr++;
+ return;
+ }
+
+ switch(path->mode) {
+ case Path::ONE_SHOT:
+ next_node_nr = path->nodes.size() - 1;
+ walking_speed = 0;
+ return;
+
+ case Path::PING_PONG:
+ walking_speed = -walking_speed;
+ next_node_nr = path->nodes.size() > 1 ? path->nodes.size() - 2 : 0;
+ return;
+
+ case Path::CIRCULAR:
+ next_node_nr = 0;
+ return;
+ }
+
+ // we shouldn't get here
+ assert(false);
+ next_node_nr = path->nodes.size() - 1;
+ walking_speed = 0;
+}
+
+void
+PathWalker::goback_node()
+{
+ current_node_nr = next_node_nr;
+
+ if(next_node_nr > 0) {
+ next_node_nr--;
+ return;
+ }
+
+ switch(path->mode) {
+ case Path::PING_PONG:
+ walking_speed = -walking_speed;
+ return;
+ default:
+ break;
+ }
+
+ assert(false);
+ next_node_nr = 0;
+ walking_speed = 0;
+}
--- /dev/null
+// $Id: path.hpp 3114 2006-03-23 23:47:04Z sommer $
+//
+// SuperTux Path
+// Copyright (C) 2005 Philipp <balinor@pnxs.de>
+// Copyright (C) 2006 Christoph Sommer <christoph.sommer@2006.expires.deltadevelopment.de>
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+// 02111-1307, USA.
+#ifndef __PATH_WALKER_HPP__
+#define __PATH_WALKER_HPP__
+
+#include "path.hpp"
+#include "math/vector.hpp"
+#include "game_object.hpp"
+#include "lisp/lisp.hpp"
+#include "serializable.hpp"
+
+/**
+ * A walker that travels along a path
+ */
+class PathWalker
+{
+public:
+ PathWalker(const Path* path);
+ virtual ~PathWalker();
+
+ /**
+ * advanves the path walker on the path and returns the position delta
+ * to the last position
+ */
+ virtual Vector advance(float elapsed_time);
+
+private:
+ void advance_node();
+ void goback_node();
+
+ const Path* path;
+
+ size_t current_node_nr;
+ size_t next_node_nr;
+
+ Vector last_pos;
+
+ /** the time we already spend in the current node */
+ float node_time;
+
+ float walking_speed;
+};
+
+#endif