# HG changeset patch
# User Daniel O'Connor <darius@dons.net.au>
# Date 1313907472 -34200
# Node ID 4b9d1b47ca179ab73749d237a37cbd63b6283315
# Parent  24e9b717722dfc62783f42b1169b136a01ccfb2c
Plot pressure.
Switch from RH to dew point to save an axis for the above.

diff -r 24e9b717722d -r 4b9d1b47ca17 static/iwws.js
--- a/static/iwws.js	Tue Aug 16 22:34:30 2011 +0930
+++ b/static/iwws.js	Sun Aug 21 15:47:52 2011 +0930
@@ -36,10 +36,11 @@
 
 function draw_graph() {
     var temp_out = [];
-    var hum_out = [];
+    var dewpt = [];
     var wavg = [];
     var wgust = [];
     var rain = [];
+    var pressure = [];
     var i, mint = 5, maxt = 35;
     var l = datacache['idx'].length - 1;
     var d = new Date();
@@ -52,25 +53,29 @@
 	if (datacache['temp_out'] < maxt)
 	    maxt = datacache['temp_out']
 	temp_out.push([t * 1000.0, datacache['temp_out'][i]]);
-	hum_out.push([t * 1000.0, datacache['hum_out'][i]]);
+	if (datacache['hum_out'][i] != null && datacache['temp_out'][i] != null) {
+	    dewpt.push([t * 1000.0, hum2dp(datacache['hum_out'][i], datacache['temp_out'][i])]);
+	}
 	wavg.push([t * 1000.0, datacache['wind_ave'][i], wind2angle(datacache['wind_dir'][i])]);
 	wgust.push([t * 1000.0, datacache['wind_gust'][i], wind2angle(datacache['wind_dir'][i])]);
+	pressure.push([t * 1000.0, datacache['abs_pressure'][i]]);
 	if (datacache['rain'][i] > 0)
 	    rain.push([t * 1000.0, datacache['rain'][i]]);
     }
     $.plot($("#graph1"), [
-	{ data : temp_out, label: "Temp.", yaxis : 1, points : { show : true }, lines : { show : true } },
-	{ data : hum_out, label: "RH", yaxis : 2, points : { show : true }, lines : { show : true } }
+	{ data : pressure, label: "Baro", yaxis : 1, points : { show : true }, lines : { show : true } },
+	{ data : temp_out, label: "Temp.", yaxis : 2, points : { show : true }, lines : { show : true } },
+	{ data : dewpt, label: "Dew point", yaxis : 2, points : { show : true }, lines : { show : true } },
     ],
 	   { xaxis : { mode : 'time' },
 	     legend : { backgroundOpacity : 0, position : 'nw' },
-	     yaxis : { min : mint, max : maxt, tickFormatter : degCFormatter },
-	     y2axis : { min : 0, max : 100, tickFormatter : pctFormatter }
+	     yaxis : { min : 950, max : 1050, tickFormatter : baroFormatter },
+	     y2axis : { min : mint, max : maxt, tickFormatter : degCFormatter },
 	   });
     $.plot($("#graph2"), [
 	{ data : wavg, label: "Wind (Avg)", yaxis : 1, points : { show : true }, lines : { show : true }, direction : true },
 	{ data : wgust, label: "Wind (Gust)", yaxis : 1, points : { show : true }, lines : { show : true }, direction : true },
-	{ data : rain, label: "Rain", yaxis : 2, bars : { show : true, barWidth : 0.5 * 60 * 60 * 1000, align : "centre" } }
+	{ data : rain, label: "Rain", yaxis : 2, bars : { show : true, barWidth : 0.5 * 60 * 60 * 1000, align : "centre" } },
     ],
 	   { xaxis : { mode : 'time' },
 	     legend : { backgroundOpacity : 0, position : 'nw' },
@@ -84,6 +89,18 @@
     return a;
 }
 
+// Formula from http://www.paroscientific.com/dewpoint.htm
+function alpha(temp, rh, a, b) {
+    return (((a * temp) / (b + temp)) + Math.log(rh / 100.0));
+}
+
+function hum2dp(rh, temp) {
+    var a = 17.27;
+    var b = 237.7;
+    var Td = (b * alpha(temp, rh, a, b)) / (a - alpha(temp, rh, a, b));
+    return Td;
+}
+
 function degCFormatter(v, axis) {
     return v.toFixed(axis.tickDecimals) +"°C";
 }
@@ -100,6 +117,10 @@
     return v.toFixed(axis.tickDecimals) + "mm";
 }
 
+function baroFormatter(v, axis) {
+    return v.toFixed(axis.tickDecimals) + "hPa";
+}
+
 function got_data(data, status) {
     if (status != "success") {
 	$.log("Couldn't load data. status = " + status);