Hello everybody,

I write in the XoJo forum because I cannot find a solution to my problem on the Intenet and I hope there is someone who is familiar with Leaflet (link: Leaflet - a JavaScript library for interactive maps - https: // leafletjs .com).

I have developed an air navigation program with XoJo. I am almost at the end of the program and I would not like to give up right now for a nonsense to which I cannot find a solution.

The question I am about to ask you is not inherent to XoJo: it is about the representation of a rotated line in the Leaflet map.

As you can see in the figure, there are two red lines C-> P1 and C-> P2 and there are blue lines C-> A, C-> B, ā¦, C-> E.

The red line C-> P1 is the starting line, the C-P2 line is the finish line. They are input data.

The blue lines are lines I calculated with the following mathematical formula:

```
// Data input
Cx = 10.247500 '=> C
Cy = 43.557778 '=> C
Ax = 10.395555 '=> P1x
Ay = 43.838056 '=> P1y
Bx = 10.64953 '=> P2x
By = 43.62996 '=> P3y
// Calculate the angle of C-> P2 with the axis
Var z, w, Angle As Double
w = ((Ax-Cx) * (Bx-Cx)) + ((Ay-Cy) * (By-Cy))
z = Sqrt (((Ax-Cx) ^ 2) + ((Ay-Cy) ^ 2)) * Sqrt (((Bx-Cx) ^ 2) + ((By-Cy) ^ 2))
Angle = (ACos (w / z)) * 180 / Pi
Var iStepRotazione As UInteger = 10 'Let's start with 10Ā° of rotation
Var xPoint, yPoint As Double
While iStepRotation <Angle
xPoint = (Ax-Cx) * Cos (iStepRotazione * Pi / 180) + (Ay-Cy) * Sin (iStepRotazione * Pi / 180) + Cx
yPoint = - (Ax-Cx) * Sin (iStepRotation * Pi / 180) + (Ay-Cy) * Cos (iStepRotation * Pi / 180) + Cy
iStepRotazione = iStepRotazione + 10 'Step of 10 Ā°
sReturn = sReturn + Str (yPoint) + "," + Str (xPoint) + ";"
Wend
```

That is, I take point P1 and rotate it by 10 Ā° until reaching P2.

With the calculated points, I create the lines (in Leaflet) C->A, C->B, etc ā¦

As you can see in the figure, the rotated points (A, B, ā¦, F) form smaller lines (the blue lines).

Iām not a great mathematician but I believe the function is correct.

Having said that, do you think it is a mathematical problem or a Web-Mercator problem?

Do you know anything about it?

Thank you.