Kotlin - Hexagonal Grip Google Maps API v3 - Optimize Code

Question

I need some help to optimize my code. Even though it works I have the strong feeling, this can be made in WAY less lines of code and much more efficient. But I can't figure it out myself.

Actually it doesn't even work perfectly yet.

I have a marker at a center. I want this center to be the center of a hexagonal grid of polygons on top of Google Maps.

In the Apps Setting the user can set the number of Hexagons he wants to have in north, east, west and south direction. So what I want to achieve is to draw all these Hexagons starting from my center of the HEX Grid.

Here you find my code which is giving me something but not exactly the right thing.

private fun drawHexagonGrid(){
        var radius = 3.5  //radius in metre
        var curPos = heartAlveole  //hierdann Heart Alveole aus den Prefs nehmen
        var northAlveoles = 5  //Das alles aus den Prefs holen.
        var eastAlveoles = 10
        var southAlveoles = 5
        var westAlveoles = 5
        val width = radius.toDouble() * 2.0 * Math.sqrt(3.0) / 2


        //North East of Heart

        curPos = heartAlveole
        for (n in 0..northAlveoles){
            //East Alveoles
            for (i in 0..eastAlveoles) {
                drawHorizontalHexagon(curPos, radius, ".")
                curPos = SphericalUtil.computeOffset(curPos, width,90.0);
            }
            curPos = SphericalUtil.computeOffset(curPos, width*eastAlveoles,270.0)
            //Every Second Iteration go half width west or east
            if (n % 2 == 0) {
                curPos = SphericalUtil.computeOffset(curPos, width/2,270.0)
            }
            else {
                curPos = SphericalUtil.computeOffset(curPos, width/2,90.0)
            }
            //go north
            curPos = SphericalUtil.computeOffset(curPos,5.25 ,0.0)

        }

        //North West of Heart

        curPos = heartAlveole
        for (n in 0..northAlveoles){
            //East Alveoles
            for (i in 0..westAlveoles) {
                drawHorizontalHexagon(curPos, radius, ".")
                curPos = SphericalUtil.computeOffset(curPos, width,270.0);
            }
            curPos = SphericalUtil.computeOffset(curPos, width*westAlveoles,90.0)

            //Every Second Iteration go half width west or east
            if (n % 2 == 0) {
                curPos = SphericalUtil.computeOffset(curPos, width/2,270.0)
            }
            else {
                curPos = SphericalUtil.computeOffset(curPos, width/2,90.0)
            }
            //go north
            curPos = SphericalUtil.computeOffset(curPos,5.25 ,0.0)

        }

        //South East of Heart

        curPos= heartAlveole
        for (n in 0..southAlveoles){
            //Every Second Iteration go half width west or east
            if (n % 2 == 0) {
                curPos = SphericalUtil.computeOffset(curPos, width/2,270.0)
            }
            else {
                curPos = SphericalUtil.computeOffset(curPos, width/2,90.0)
            }
            //go south
            curPos = SphericalUtil.computeOffset(curPos,5.25 ,180.0)
            //East Alveoles
            for (i in 0..eastAlveoles) {
                drawHorizontalHexagon(curPos, radius, ".")
                curPos = SphericalUtil.computeOffset(curPos, width,90.0);
            }

            curPos = SphericalUtil.computeOffset(curPos, width*eastAlveoles,270.0)


        }

        //South West of Heart

        curPos= heartAlveole
        for (n in 0..southAlveoles){
            //Every Second Iteration go half width west or east
            if (n % 2 == 0) {
                curPos = SphericalUtil.computeOffset(curPos, width/2,270.0)
            }
            else {
                curPos = SphericalUtil.computeOffset(curPos, width/2,90.0)
            }
            //go south
            curPos = SphericalUtil.computeOffset(curPos,5.25 ,180.0)
            //West Alveoles
            for (i in 0..westAlveoles) {
                drawHorizontalHexagon(curPos, radius, ".")
                curPos = SphericalUtil.computeOffset(curPos, width,270.0);
            }

            curPos = SphericalUtil.computeOffset(curPos, width*westAlveoles,90.0)

        }



    }

    private fun drawHorizontalHexagon(position : LatLng, radius : Double, label : String){
        var coordinates : MutableList<LatLng> = arrayListOf()

        for (angle in 0..360 step 60) {
            coordinates.add(SphericalUtil.computeOffset(position,radius,angle.toDouble()))
        }

        var opts : PolygonOptions = PolygonOptions().addAll(coordinates)
            .fillColor(Color.argb(35,255, 0,0))
            .strokeColor(Color.RED).strokeWidth(3f)

        mMap.addPolygon(opts)


        //Funktioniert theoretisch. Noch überlegen ob ich es wirklich brauche.
        //Müsste noch das Transparent ändern und die Größe der Schrift anpassen.
        //this.showText(position, label)

    }

As you can see, I have the drawHexagon function. As well as some Looping functions. Going south you have to iterate between going half width to the left or to the right. It's not as trivial as it looks ;)

Thanks for all your help!

Alex · Answer 1 · 2019-02-21T11:42:52.173

I have found an answer myself. I will post it here for the archive if someone has the same problem.

private fun drawHexagonGrid(){
    var radius = 3.5  //radius in metre
    var curPos = heartAlveole  //hierdann Heart Alveole aus den Prefs nehmen
    var northAlveoles = 5  //Das alles aus den Prefs holen.
    var eastAlveoles = 10
    var southAlveoles = 5
    var westAlveoles = 5
    val width = radius.toDouble() * 2.0 * Math.sqrt(3.0) / 2


    //Move to NorthWest Corner of HexGrid

    val westMove = if (northAlveoles % 2 == 0) width*westAlveoles else (width*westAlveoles)-(width/2)

    //If northAlveoles is unequal, add half width to westMove to

    curPos = SphericalUtil.computeOffset(curPos,westMove,270.0)
    curPos = SphericalUtil.computeOffset(curPos,radius * 6/4*northAlveoles,0.0)

    //nested for loop to produce hexagonal grid

    for (n in 1..northAlveoles+southAlveoles+1){
        //draw horizontal hexagons
        for (e in 1..eastAlveoles+westAlveoles+1) {
            drawHorizontalHexagon(curPos, radius, ".")
            curPos = SphericalUtil.computeOffset(curPos, width,90.0);
        }

        //Go back to the initial position + width/2 or - width/2 every second iteration
        if (n % 2 == 0) {
            curPos = SphericalUtil.computeOffset(curPos, width*((westAlveoles+eastAlveoles)+0.5),270.0)
        } else {
            curPos = SphericalUtil.computeOffset(curPos, width*((westAlveoles+eastAlveoles)+1.5),270.0)
        }
        //go south
        curPos = SphericalUtil.computeOffset(curPos,radius * 6/4 ,180.0)
    }
}

Kotlin - Hexagonal Grip Google Maps API v3 - Optimize Code

1 Answers1