+// FGMagRibbon.cxx - Built-in layer for the magnetic compass ribbon layer.
+//
+// Written by David Megginson, started January 2000.
+//
+// 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+//
+// $Id$
+
+
+#include "FGMagRibbon.hxx"
+#include "../steam.hxx"
+
+
+FGMagRibbon::FGMagRibbon (int w, int h)
+ : FGTexturedLayer(w, h)
+{
+ FGCroppedTexture texture("Aircraft/Instruments/Textures/compass-ribbon.rgb");
+ setTexture(texture);
+}
+
+void
+FGMagRibbon::draw ()
+{
+ double heading = FGSteam::get_MH_deg();
+ double xoffset, yoffset;
+
+ while (heading >= 360.0) {
+ heading -= 360.0;
+ }
+ while (heading < 0.0) {
+ heading += 360.0;
+ }
+
+ if (heading >= 60.0 && heading <= 180.0) {
+ xoffset = heading / 240.0;
+ yoffset = 0.75;
+ } else if (heading >= 150.0 && heading <= 270.0) {
+ xoffset = (heading - 90.0) / 240.0;
+ yoffset = 0.50;
+ } else if (heading >= 240.0 && heading <= 360.0) {
+ xoffset = (heading - 180.0) / 240.0;
+ yoffset = 0.25;
+ } else {
+ if (heading < 270.0)
+ heading += 360.0;
+ xoffset = (heading - 270.0) / 240.0;
+ yoffset = 0.0;
+ }
+
+ xoffset = 1.0 - xoffset;
+ // Adjust to put the number in the centre
+ xoffset -= 0.25;
+
+ FGCroppedTexture &t = getTexture();
+ t.setCrop(xoffset, yoffset, xoffset + 0.5, yoffset + 0.25);
+ FGTexturedLayer::draw();
+}
+
+// end of FGMagRibbon.cxx