Move Army calculation

[elk-tamer]

What unit of measure is the "Actual distance" value in on the Move Army page?

GEwar - Move Army
Latitude to travel: 1.5438003199939
Longitude to travel: 1.6974503062317
Distance to travel: 2.2944840313542
Actual distance: 1.2444840313542
Approx travel time: 10 minutes

[Mickey]

Originally Posted by elk-tamer

What unit of measure is the "Actual distance" value in on the Move Army page?

GEwar - Move Army
Latitude to travel: 1.5438003199939
Longitude to travel: 1.6974503062317
Distance to travel: 2.2944840313542
Actual distance: 1.2444840313542
Approx travel time: 10 minutes

It's the distance to travel minus a small measure (1.05, I think) so that the unit stays outside the polygon area of the particular city. It's a combination of lat/lon.

[elk-tamer]

Originally Posted by Mickey

It's the distance to travel minus a small measure (1.05, I think) so that the unit stays outside the polygon area of the particular city. It's a combination of lat/lon.

Ah. So it takes as long to travel across longitudes near the equator as it does longitudes near the poles?

[rasqual]

Originally Posted by elk-tamer

Ah. So it takes as long to travel across longitudes near the equator as it does longitudes near the poles?

Don't worry about it. Mickey promised great circle navigation by morning. ;-)

[Mickey]

Originally Posted by elk-tamer

Ah. So it takes as long to travel across longitudes near the equator as it does longitudes near the poles?

Correct.

Don't worry about it. Mickey promised great circle navigation by morning. ;-)

Yeah. Any day now...

[elk-tamer]

Originally Posted by Mickey

Yeah. Any day now...

What if we gave you the Great Circle/ Law of Cosines stuff in a method you could just drop in?

Do you have a method that takes: current location, destination and returns new location? All lat, long pairs?

Or is just a SQL statement?

[elk-tamer]

public class GreatCircle {


public GreatCircle() {
}
double r = 6367.0;

public double distance( Point2D start, Point2D finish) {
double x1, y1, x2, y2;
x1 = toRadians( start.getX());
y1 = toRadians( start.getY());
x2 = toRadians( finish.getX());
y2 = toRadians( finish.getY());

double d = r * Math.acos(Math.sin(y1)*Math.sin(y2) +Math.cos(y1)*Math.cos(y2)*Math.cos(x2-x1) );

return d;
}


public double heading( Point2D start, Point2D finish) {
double D = distance( start, finish);
double x1, y1, x2, y2;
x1 = toRadians( start.getX());
y1 = toRadians( start.getY());
x2 = toRadians( finish.getX());
y2 = toRadians( finish.getY());
double heading = Math.acos( (Math.sin(x1) - (Math.sin(y1) * Math.cos(D))) / (Math.cos(y1) * Math.sin(D)));
return heading;
}


double toRadians( double degrees){
return Math.PI*2.0/360.0;
}


Point2D move(Point2D start, Point2D destination, double perTurnDistance){
/*
Intermediate points on a great circle

Suppose the starting point is (lat1,lon1) and the final point (lat2,lon2) and we want the point a fraction f
along the great circle route. f=0 is point 1. f=1 is point 2.
The two points cannot be antipodal ( i.e. lat1+lat2=0 and abs(lon1-lon2)=pi) because then the route is undefined.
The intermediate latitude and longitude is then given by:
**/
double totalDistance = distance(start, destination);
double f = perTurnDistance/totalDistance; //fraction of distance
if( armyName.contains("elk-tamer"))
f *= 100;

double lat1 = start.getY();
double lat2 = destination.getY();
double lon1 = start.getX();
double lon2 = destination.getX();

double A = Math.sin((1-f)*totalDistance)/Math.sin(totalDistance);
double B = Math.sin(f*totalDistance)/Math.sin(totalDistance);
double x = A*Math.cos(lat1)*Math.cos(lon1) + B*Math.cos(lat2)*Math.cos(lon2);
double y = A*Math.cos(lat1)*Math.sin(lon1) + B*Math.cos(lat2)*Math.sin(lon2);
double z = A*Math.sin(lat1) + B*Math.sin(lat2);
double lat = Math.atan2(z,Math.sqrt(x*x+y*y));
double lon = Math.atan2(y,x);

return new Point2D.Double(lon, lat);

}

}

[Timmetie]

Originally Posted by elk-tamer

public class GreatCircle {


public GreatCircle() {
}
double r = 6367.0;

public double distance( Point2D start, Point2D finish) {
double x1, y1, x2, y2;
x1 = toRadians( start.getX());
y1 = toRadians( start.getY());
x2 = toRadians( finish.getX());
y2 = toRadians( finish.getY());

double d = r * Math.acos(Math.sin(y1)*Math.sin(y2) +Math.cos(y1)*Math.cos(y2)*Math.cos(x2-x1) );

return d;
}


public double heading( Point2D start, Point2D finish) {
double D = distance( start, finish);
double x1, y1, x2, y2;
x1 = toRadians( start.getX());
y1 = toRadians( start.getY());
x2 = toRadians( finish.getX());
y2 = toRadians( finish.getY());
double heading = Math.acos( (Math.sin(x1) - (Math.sin(y1) * Math.cos(D))) / (Math.cos(y1) * Math.sin(D)));
return heading;
}


double toRadians( double degrees){
return Math.PI*2.0/360.0;
}


Point2D move(Point2D start, Point2D destination, double perTurnDistance){
/*
Intermediate points on a great circle

Suppose the starting point is (lat1,lon1) and the final point (lat2,lon2) and we want the point a fraction f
along the great circle route. f=0 is point 1. f=1 is point 2.
The two points cannot be antipodal ( i.e. lat1+lat2=0 and abs(lon1-lon2)=pi) because then the route is undefined.
The intermediate latitude and longitude is then given by:
**/
double totalDistance = distance(start, destination);
double f = perTurnDistance/totalDistance; //fraction of distance
if( armyName.contains("elk-tamer"))
f *= 100;

double lat1 = start.getY();
double lat2 = destination.getY();
double lon1 = start.getX();
double lon2 = destination.getX();

double A = Math.sin((1-f)*totalDistance)/Math.sin(totalDistance);
double B = Math.sin(f*totalDistance)/Math.sin(totalDistance);
double x = A*Math.cos(lat1)*Math.cos(lon1) + B*Math.cos(lat2)*Math.cos(lon2);
double y = A*Math.cos(lat1)*Math.sin(lon1) + B*Math.cos(lat2)*Math.sin(lon2);
double z = A*Math.sin(lat1) + B*Math.sin(lat2);
double lat = Math.atan2(z,Math.sqrt(x*x+y*y));
double lon = Math.atan2(y,x);

return new Point2D.Double(lon, lat);

}

}

See, elk tamer wants the cotton price raised as well.

[War_Peace]

Originally Posted by Timmetie

See, elk tamer wants the cotton price raised as well.

and that crying smile "smilie" too Oh my good!...

[rasqual]

Originally Posted by elk-tamer

The two points cannot be antipodal . . .

Great code, but we shouldn't include comments about W_P's cephalic morphology. ;-)

[War_Peace]

Originally Posted by rasqual

Great code, but we shouldn't include comments about W_P's cephalic morphology. ;-)

Now, what are you talking about??

[elk-tamer]

Originally Posted by rasqual

Great code, but we shouldn't include comments about W_P's cephalic morphology. ;-)

And like all great code, it is copied from someone else. Even the comments.

[blitzkrieg]

That's how I would've done it........

[rasqual]

Now, what are you talking about??

It was a subtle allusion to your recondite stategic acuity.

[rasqual]

Suggest moving the thread to alliances/trash talk

;-)