first cut at turnon scripts for EasyTimer v2

[fw/altos] / altoslib / AltosRotation.java

diff --git a/altoslib/AltosRotation.java b/altoslib/AltosRotation.java
index 305f932a0330f158fc363d0f140fe285b0facd6a..85e213b25f5a0ef0700c3151b6723ee8ff34b925 100644 (file)
--- a/altoslib/AltosRotation.java
+++ b/altoslib/AltosRotation.java
@@ -16,7 +16,7 @@
  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  */
 
-package org.altusmetrum.altoslib_12;
+package org.altusmetrum.altoslib_14;
 
 public class AltosRotation extends AltosQuaternion {
        private AltosQuaternion         rotation;
@@ -29,7 +29,7 @@ public class AltosRotation extends AltosQuaternion {
         *
         * rot = ao_rotation * vertical * ao_rotation°
         * rot = ao_rotation * (0,0,0,1) * ao_rotation°
-        *     = ((a.z, a.y, -a.x, a.r) * (a.r, -a.x, -a.y, -a.z)) .z
+        *     = ((-a.z, a.y, -a.x, a.r) * (a.r, -a.x, -a.y, -a.z)) .z
         *
         *     = (-a.z * -a.z) + (a.y * -a.y) - (-a.x * -a.x) + (a.r * a.r)
         *     = a.z² - a.y² - a.x² + a.r²
@@ -40,7 +40,7 @@ public class AltosRotation extends AltosQuaternion {
         *     = (a.z * -a.z) + (-a.y * -a.y) - (a.x * -a.x) + (-a.r * a.r)
         *     = -a.z² + a.y² + a.x² - a.r²
         *
-        * tilt = acos(rot); /* in radians */
+        * tilt = acos(rot)  (in radians)
         */
 
        public double tilt() {
@@ -50,6 +50,34 @@ public class AltosRotation extends AltosQuaternion {
                return tilt;
        }
 
+       /* Compute azimuth angle from a reference line pointing out the side
+        * of the airframe
+        *
+        * rot = ao_rotation * x_axis * ao_rotation°
+        * rot = ao_rotation * (0,1,0,0) * ao_rotation°
+        *     = (-a.x, a.r, a.z, -a.y) * (a.r, -a.x, -a.y, -a.z) . x
+        *     = (-a.x * -a.x) + (a.r * a.r) + (a.z * -a.z) - (-a.y * -a.y)
+        *     = a.x² + a.r² - a.z² - a.y²
+        *
+        *     = (-a.x, a.r, a.z, -a.y) * (a.r, -a.x, -a.y, -a.z) . y
+        *     = (-a.x * -a.y) - (a.r * -a.z) + (a.z * a.r) + (-a.y * -a.x)
+        *     = a.x * a.y + a.r * a.z + a.z * a.r + a.y * a.x
+        *
+        * The X value will be the cosine of the rotation. The Y value will be the
+        * sine of the rotation; use the sign of that to figure out which direction from
+        * zero we've headed
+        */
+
+       public double azimuth() {
+               double rotx = rotation.x * rotation.x + rotation.r * rotation.r - rotation.z * rotation.z - rotation.y * rotation.y;
+               double roty = rotation.x * rotation.y + rotation.r * rotation.z + rotation.z * rotation.r + rotation.y * rotation.x;
+
+               double az = Math.acos(rotx) * 180.0 / Math.PI;
+               if (roty < 0)
+                       return -az;
+               return az;
+       }
+
        /* Given euler rotations in three axes, perform a combined rotation using
         * quaternions
         */
@@ -69,7 +97,7 @@ public class AltosRotation extends AltosQuaternion {
                             double z,
                             int pad_orientation) {
                AltosQuaternion orient = AltosQuaternion.vector(x, y, z).normalize();
-               double sky = pad_orientation == 0 ? 1 : -1;
+               double sky = (pad_orientation & 1) == 0 ? 1 : -1;
                AltosQuaternion up = new AltosQuaternion(0, 0, 0, sky);
                rotation = up.vectors_to_rotation(orient);
        }