altoslib: Compute tilt angle from eeprom data

[fw/altos] / altoslib / AltosRotation.java

diff --git a/altoslib/AltosRotation.java b/altoslib/AltosRotation.java
new file mode 100644 (file)
index 0000000..ad5aca8
--- /dev/null
+++ b/altoslib/AltosRotation.java
@@ -0,0 +1,50 @@
+/*
+ * Copyright © 2014 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * 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.
+ */
+
+package org.altusmetrum.altoslib_5;
+
+public class AltosRotation {
+       private AltosQuaternion         rotation;
+
+       public double tilt() {
+               double  rotz = rotation.z * rotation.z - rotation.y * rotation.y - rotation.x * rotation.x + rotation.r * rotation.r;
+
+               double tilt = Math.acos(rotz) * 180.0 / Math.PI;
+               return tilt;
+       }
+
+       public void rotate(double dt, double x, double y, double z) {
+               AltosQuaternion rot = AltosQuaternion.half_euler(x * dt, y * dt, z * dt);
+               rotation = rot.multiply(rotation).normalize();
+       }
+
+       /* Clone an existing rotation value */
+       public AltosRotation (AltosRotation old) {
+               this.rotation = new AltosQuaternion(old.rotation);
+       }
+
+       /* Create a new rotation value given an acceleration vector pointing down */
+       public AltosRotation(double x,
+                            double y,
+                            double z,
+                            int pad_orientation) {
+               AltosQuaternion orient = AltosQuaternion.vector(x, y, z).normalize();
+               double sky = pad_orientation == 0 ? 1 : -1;
+               AltosQuaternion up = new AltosQuaternion(0, 0, 0, sky);
+               rotation = up.vectors_to_rotation(orient);
+       }
+}