Fix true wind computation bug, add swipe gesture to pause GPS

apps/openwind/ChangeLog

@@ -1 +1,2 @@
 0.01: New App!
+0.02: Fix true wind computation, add swipe gesture to pause GPS

apps/openwind/README.md

@@ -14,7 +14,9 @@ additionally displayed in red.  In this mode, the speed over ground in knots is
 
 ## Controls
 
-There are no controls in the main app, but there are two settings in the settings app that can be changed:
+In the main app, when true wind mode is enabled (see below), swiping left on the screen will temporarily disable GPS (to preserve battery); a small
+red satellite symbol will appear on the bottom right. Swiping right will turn GPS back on.
+The settings app provides the following two settings:
 
  * True wind: enables or disables true wind calculations; enabling this will turn on GPS inside the app
  * Mounting angle: mounting relative to the boat of the wind instrument (in degrees)

apps/openwind/app.js

@@ -1,16 +1,20 @@
 OW_CHAR_UUID = '0000cc91-0000-1000-8000-00805f9b34fb';
 require("Font7x11Numeric7Seg").add(Graphics);
-gatt = {};
-cx = g.getWidth()/2;
-cy = 24+(g.getHeight()-24)/2;
-w = (g.getWidth()-24)/2;
-
-gps_course = { spd: 0 };
+var gatt = {};
+var cx = g.getWidth()/2;
+var cy = 24+(g.getHeight()-24)/2;
+var w = (g.getWidth()-24)/2;
+var y1 = 24;
+var y2 = g.getHeight()-1;
+var gps_course = { spd: 0 };
+var course_marker_len = g.getWidth()/4;
 
 var settings = require("Storage").readJSON('openwindsettings.json', 1) || {};
 
-i = 0;
-hullpoly = [];
+var pause_gps = false;
+
+var i = 0;
+var hullpoly = [];
 for (y=-1; y<=1; y+=0.1) {
   hullpoly[i++] = cx - (y<0 ? 1+y*0.15 : (Math.sqrt(1-0.7*y*y)-Math.sqrt(0.3))/(1-Math.sqrt(0.3)))*w*0.3;
   hullpoly[i++] = cy - y*w*0.7;
@@ -22,17 +26,18 @@ for (y=1; y>=-1; y-=0.1) {
 
 function wind_updated(ev) {
   if (ev.target.uuid == "0xcc91") {
-    awa = settings.mount_angle-ev.target.value.getInt16(1, true)*0.1;
+    awa = settings.mount_angle+ev.target.value.getInt16(1, true)*0.1;
+    if (awa<0) awa += 360;
     aws = ev.target.value.getInt16(3, true)*0.01;
-//    console.log(awa, aws);
+    //console.log(awa, aws);
     if (gps_course.spd > 0) {
-      wv = { // wind vector (in fixed reference frame)
-        lon: Math.sin(Math.PI*(gps_course.course+awa)/180)*aws,
-        lat: Math.cos(Math.PI*(gps_course.course+awa)/180)*aws
+      wv = { // wind vector (in "earth" reference frame)
+        vlon: Math.sin(Math.PI*(gps_course.course+(awa+180))/180)*aws,
+        vlat: Math.cos(Math.PI*(gps_course.course+(awa+180))/180)*aws
       };
-      twv = { lon: wv.lon+gps_course.lon, lat: wv.lat+gps_course.lat  };
-      tws = Math.sqrt(Math.pow(twv.lon,2)+Math.pow(twv.lat, 2));
-      twa = Math.atan2(twv.lat, twv.lon)*180/Math.PI-gps_course.course;
+      twv = { vlon: wv.vlon+gps_course.vlon, vlat: wv.vlat+gps_course.vlat  };
+      tws = Math.sqrt(Math.pow(twv.vlon,2)+Math.pow(twv.vlat, 2));
+      twa = 180+Math.atan2(twv.vlon, twv.vlat)*180/Math.PI-gps_course.course;
       if (twa<0) twa += 360;
       if (twa>360) twa -=360;
     }
@@ -57,15 +62,18 @@ function draw_compass(awa, aws, twa, tws) {
     a = i*Math.PI/2+Math.PI/4;
     g.drawLineAA(cx+Math.cos(a)*w*0.85, cy+Math.sin(a)*w*0.85, cx+Math.cos(a)*w*0.99, cy+Math.sin(a)*w*0.99);
   }
-  g.setColor(0, 1, 0).fillCircle(cx+Math.sin(Math.PI*awa/180)*w*0.9, cy+Math.cos(Math.PI*awa/180)*w*0.9, w*0.1);
+  g.setColor(0, 1, 0).fillCircle(cx+Math.sin(Math.PI*awa/180)*w*0.9, cy-Math.cos(Math.PI*awa/180)*w*0.9, w*0.1);
   if (tws>0) g.setColor(1, 0, 0).fillCircle(cx+Math.sin(Math.PI*twa/180)*w*0.9, cy+Math.cos(Math.PI*twa/180)*w*0.9, w*0.1);
   g.setColor(0, 1, 0).setFont("7x11Numeric7Seg",w*0.06);
   g.setFontAlign(0, 0, 0).drawString(aws.toFixed(1), cx, cy-0.32*w);
+  if (!pause_gps) {
     if (tws>0) g.setColor(1, 0, 0).drawString(tws.toFixed(1), cx, cy+0.32*w);
-  if (settings.truewind && typeof gps_course.spd!=='undefined') {
+    if (settings.truewind && gps_course.spd!=-1) {
       spd = gps_course.spd/1.852;
       g.setColor(g.theme.fg).setFont("7x11Numeric7Seg", w*0.03).setFontAlign(-1, 1, 0).drawString(spd.toFixed(1), 1, g.getHeight()-1);
     }
+  }
+  if (pause_gps) g.setColor("#f00").drawImage(atob("DAwBEAKARAKQE4DwHkPqPRGKAEAA"),g.getWidth()-15, g.getHeight()-15);
 }
 
 function parseDevice(d) {
@@ -96,8 +104,10 @@ if (settings.truewind) {
   Bangle.on('GPS',function(fix) {
     if (fix.fix && fix.satellites>3 && fix.speed>2) { // only uses fixes w/ more than 3 sats and speed > 2kph
       gps_course = 
-        { lon: Math.sin(Math.PI*fix.course/180)*fix.speed/1.852,
-          lat: Math.cos(Math.PI*fix.course/180)*fix.speed/1.852,
+        { vlon: Math.sin(Math.PI*fix.course/180)*fix.speed/1.852,
+          vlat: Math.cos(Math.PI*fix.course/180)*fix.speed/1.852,
+	        lat: fix.lat,
+	        lon: fix.lon,
           spd: fix.speed,
           course: fix.course
         };
@@ -107,6 +117,20 @@ if (settings.truewind) {
   Bangle.setGPSPower(1, "app");
 }
 
+if (settings.truewind) {
+  Bangle.on("swipe", (d)=>{
+    if (d==-1 && !pause_gps) {
+      pause_gps = true;
+      Bangle.setGPSPower(0);
+      draw_compass(0, 0, 0, 0);
+    }
+    else if (d==1 && pause_gps) {
+      pause_gps = false;
+      Bangle.setGPSPower(1, "app");
+      draw_compass(0, 0, 0, 0);
+    }
+  });
+}
 Bangle.loadWidgets();
 Bangle.drawWidgets();
 draw_compass(0, 0, 0, 0);

apps/openwind/metadata.json

@@ -1,7 +1,7 @@
 { "id": "openwind",
   "name": "OpenWind",
   "shortName":"OpenWind",
-  "version":"0.01",
+  "version":"0.02",
   "description": "OpenWind",
   "icon": "openwind.png",
   "readme": "README.md",