1 files changed, 50 insertions, 0 deletions
diff --git a/altoslib/AltosRotation.java b/altoslib/AltosRotation.java
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+++ b/altoslib/AltosRotation.java
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+/*
+ * 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_6;
+
+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);
+	}
+}