Cartesian coordinates

src/coords.c

@@ -0,0 +1,51 @@
+/*
+ * IGC parser - coordinates transformation
+ * @brief parse IGC file, get all data points, compute average horizontal/vertical speed, print to STDOUT
+ *
+ * As per standard: https://xp-soaring.github.io/igc_file_format/igc_format_2008.html
+ *                  https://xp-soaring.github.io/igc_file_format/igc_fr_specification_with_al8_2023-2-1_0.pdf
+ *
+ * @author xamidev <xamidev@riseup.net>
+ * @license GNU GPL v3
+ */
+
+#include "igc.h"
+#include <math.h>
+
+// Approximate radius of the Earth, in kilometers
+#define EARTH_RADIUS 6371*1000
+
+void compute_decimal_coords(struct IGC_DataPoint* dp)
+{
+	double lat = dp->lat.deg + dp->lat.min/60.0 + dp->lat.sec/3600.0;
+	double lon = dp->lon.deg + dp->lon.min/60.0 + dp->lon.sec/3600.0;
+
+	if (dp->lat.cardinal == SOUTH)
+	{
+		lat = -lat;
+	}
+
+	if (dp->lon.cardinal == WEST)
+	{
+		lon = -lon;
+	}
+
+	dp->lat.decimal = lat;
+	dp->lon.decimal = lon;
+	
+	printf("DEBUG: %lf, %lf\n", dp->lat.decimal, dp->lon.decimal);
+}
+
+void compute_cartesian_coords(struct IGC_DataPoint* dp)
+{
+	double rad_lat = dp->lat.decimal*(M_PI/180.0);
+	double rad_lon = dp->lon.decimal*(M_PI/180.0);
+	printf("DEBUG: %lf, %lf\n", rad_lat, rad_lon);
+
+	double x = EARTH_RADIUS * cos(rad_lat) * cos(rad_lon);
+	double y = EARTH_RADIUS * cos(rad_lat) * sin(rad_lon);
+
+	dp->lon.meters = x;
+	dp->lat.meters = y;
+	printf("DEBUG: x=%lf, y=%lf\n", x, y);
+}

src/coords.h

@@ -0,0 +1,18 @@
+/*
+ * IGC parser
+ * @brief parse IGC file, get all data points, compute average horizontal/vertical speed, print to STDOUT
+ *
+ * As per standard: https://xp-soaring.github.io/igc_file_format/igc_format_2008.html
+ *                  https://xp-soaring.github.io/igc_file_format/igc_fr_specification_with_al8_2023-2-1_0.pdf
+ *
+ * @author xamidev <xamidev@riseup.net>
+ * @license GNU GPL v3
+ */
+
+#ifndef COORDS_H
+#define COORDS_H
+
+void compute_decimal_coords(struct IGC_DataPoint* dp);
+void compute_cartesian_coords(struct IGC_DataPoint* dp);
+
+#endif

src/igc.c

@@ -16,6 +16,7 @@
 #include <string.h>
 #include "igc.h"
 #include "linkage.h"
+#include "coords.h"
 
 struct IGC_DataPoint* parse_datapoint(char* line)
 {
@@ -58,6 +59,8 @@ struct IGC_DataPoint* parse_datapoint(char* line)
 void show_datapoint(struct IGC_DataPoint* dp)
 {
 	printf("Data point: %02d:%02d:%02d | %d°%d'%d\"%c %d°%d'%d\"%c | Baro: %dm GPS: %dm\n", dp->hour, dp->minute, dp->second, dp->lat.deg, dp->lat.min, dp->lat.sec, dp->lat.cardinal, dp->lon.deg, dp->lon.min, dp->lon.sec, dp->lon.cardinal, dp->baro_alt, dp->gps_alt);
+	compute_decimal_coords(dp);	
+	compute_cartesian_coords(dp);
 }
 
 void show_header_info(struct IGC_Header* hdr)

src/igc.h

@@ -13,6 +13,7 @@
 #define NAME_MAX 256
 #define TMP_SIZE 8
 
+#include <stdio.h>
 #include "linkage.h"
 
 enum IGC_RecordType
@@ -41,10 +42,17 @@ enum Cardinals
 
 struct Coord
 {
+	// Sexagesimal (Deg/min/sec Cardinal)
 	char cardinal;
 	int deg;
 	int min;
 	int sec;
+
+	// Decimal degrees
+	double decimal;
+
+	// Cartesian units (meters)
+	double meters;
 };
 
 struct IGC_Header