ECF to ECI convertion.

CHANGELOG.md

@@ -1,7 +1,10 @@
+## [2.0.7]
+
+* ECF to ECI convertion.
+
 ## [2.0.6]
 
 * Julian to DateTime convertion.
-
 ## [2.0.5]
 
 * Julian constructor is public.

README.md

@@ -16,3 +16,12 @@ Then, in your code import:
 ```dart
 import 'package:latlng/latlng.dart';
 ```
+
+## Features
+
+* Julian date and time.
+* ECI and ECF Calculations.
+* Look Angle Calculation.
+* Ground Track.
+* WGS84 and WGS72.
+* Projection to Tile Index.

lib/src/ecef.dart

@@ -14,19 +14,32 @@ class EarthCenteredEarthFixed {
   /// Z Coordinate.
   final double z;
 
-  EarthCenteredEarthFixed operator +(EarthCenteredEarthFixed other) {
-    final dx = x + other.x;
-    final dy = x + other.y;
-    final dz = x + other.z;
+  /// Convert this ECF to ECI.
+  EarthCenteredInertial toEci(Angle gmst) {
+    // ccar.colorado.edu/ASEN5070/handouts/coordsys.doc
+    //
+    // [X]     [C -S  0][X]
+    // [Y]  =  [S  C  0][Y]
+    // [Z]eci  [0  0  1][Z]ecf
+    //
+    var dx = x * cos(gmst.radians) - y * sin(gmst.radians);
+    var dy = x * sin(gmst.radians) + y * cos(gmst.radians);
+    var dz = z;
+
+    return EarthCenteredInertial(dx, dy, dz);
+  }
+
+  /// Convert this ECF to ECI.
+  EarthCenteredInertial toEciByDateTime(DateTime utc) =>
+      toEci(utc.toUtc().gsmt);
 
-    return EarthCenteredEarthFixed(dx, dy, dz);
+  /// Sum of two ECFs.
+  EarthCenteredEarthFixed operator +(EarthCenteredEarthFixed other) {
+    return EarthCenteredEarthFixed(x + other.x, y + other.y, z + other.z);
   }
 
+  /// Sub of two ECFs.
   EarthCenteredEarthFixed operator -(EarthCenteredEarthFixed other) {
-    final dx = x - other.x;
-    final dy = x - other.y;
-    final dz = x - other.z;
-
-    return EarthCenteredEarthFixed(dx, dy, dz);
+    return EarthCenteredEarthFixed(x - other.x, y - other.y, z - other.z);
   }
 }

lib/src/eci.dart

@@ -15,6 +15,14 @@ class EarthCenteredInertial {
   /// Z Coordinate.
   final double z;
 
+  EarthCenteredInertial operator +(EarthCenteredInertial other) {
+    return EarthCenteredInertial(x + other.x, y + other.y, z + other.z);
+  }
+
+  EarthCenteredInertial operator -(EarthCenteredInertial other) {
+    return EarthCenteredInertial(x - other.x, y - other.y, z - other.z);
+  }
+
   /// Converts this ECI object to ECF.
   EarthCenteredEarthFixed toEcf(Angle gmst) {
     final s = sin(gmst.radians);

pubspec.yaml

@@ -1,6 +1,6 @@
 name: latlng
 description: GeoJSON, Geodesy and Geographical calculations for Dart. Provides LatLong and Mercator projection (EPSG4326).
-version: 2.0.6
+version: 2.0.7
 repository: https://github.com/xclud/dart_latlng
 homepage: https://pwa.ir