Weather data value to rotation

[Markkyboy]

I've made a barometer gauge, starting from 970 hPa (from: -130 degrees/angle) --> 1070 hPa (to: +130 degrees/angle)

I'm using Openweathermap.org to get actual pressure data (shown bottom of image)

How do I calculate the angle of the needle using the pressure data?, I guess it's a job for javascript and as such, have searched exstensively but haven't found anything relevant and am not really sure how to tackle it. Any info/ideas gratefully received.

[J.Hilk]

@Markkyboy quote from my previous post:

//Mapping follows: Y = (X-minRangeOld)/(maxRangeOld-minRangeOld) * (maxRangeNew-minRangeNew) + minRangeNew

just implement that in QML if you don't want to use the c++/template

---

function mapToRange(x, maxRangeOld, minRangeOld,maxRangeNew, minRangeNew)
    {
        return (x-minRangeOld)/(maxRangeOld-minRangeOld) * (maxRangeNew-minRangeNew) + minRangeNew
    }


CircularSlider {
           id: barometer
           width: 400
           height: width
           interactive: false
           minValue:    -130
           maxValue:    130
           startAngle:  -130
           endAngle:    130
           anchors.centerIn: parent
           value:  0
           //Mapping follows: Y = (X-minRangeOld)/(maxRangeOld-minRangeOld) * (maxRangeNew-minRangeNew) + minRangeNew
           angle: mapToRange(value,1070, 970, 130, -130)

....

[J.Hilk]

@Markkyboy

taken from my function collection:

template<typename typeIn, typename typeOut>
auto mapToRange(typeIn value,
                    typeIn inMax = std::numeric_limits<typeIn>::max(),
                    typeIn inMin = std::numeric_limits<typeIn>::min(),
                    typeOut outMax = std::numeric_limits<typeOut>::max(),
                    typeOut outMin = std::numeric_limits<typeOut>::min() ){
    //Mapping follows: Y = (X-minRangeOld)/(maxRangeOld-minRangeOld) * (maxRangeNew-minRangeNew) + minRangeNew
    auto mapped = (static_cast<double>(value) - inMin) / (inMax - inMin) * (outMax - outMin) +  outMin;

    return static_cast<typeOut>(mapped);
}

int main(int argc, char *argv[])
{

    for(int i{970}; i < 1071; i++){
        int result = mapToRange<int,int>(i,970, 1070, -130, 130);
        qDebug() << i << "to" << result;
    }
}

[Markkyboy]

@J-Hilk said in Weather data value to rotation:

template<typename typeIn, typename typeOut>
auto mapToRange(typeIn value,
typeIn inMax = std::numeric_limits<typeIn>::max(),
typeIn inMin = std::numeric_limits<typeIn>::min(),
typeOut outMax = std::numeric_limits<typeOut>::max(),
typeOut outMin = std::numeric_limits<typeOut>::min() ){
//Mapping follows: Y = (X-minRangeOld)/(maxRangeOld-minRangeOld) * (maxRangeNew-minRangeNew) + minRangeNew
auto mapped = (static_cast<double>(value) - inMin) / (inMax - inMin) * (outMax - outMin) + outMin;

return static_cast<typeOut>(mapped);

}

Thank you, but how do I use that in the QML side of things?, I'm using a Repeater with Rotation (origin.x, origin.y, angle) inside CircularSlider.

I have added your data to my main.cpp successfully, but where to go from there?

    CircularSlider {
        id: barometer
        width: 400
        height: width
        interactive: false
        minValue:    -130
        maxValue:    130 
        startAngle:  -130
        endAngle:    130 
        anchors.centerIn: parent
        value:  0

        Repeater {
            id: ind
            model: 1
            Rectangle {
                z: 2
                id: indicator
                width: 3
                height: 160
                color: "orange"
                smooth: true
                antialiasing: true
                transform: [ Translate {
                        x: barometer.width / 2 - width / 2
                        y: 35
                    },
                    Rotation {
                        origin.x: barometer.width / 2
                        origin.y: barometer.height / 2
                        angle: barometer.angle
                    }
                ]
            }
        }

[J.Hilk]

@Markkyboy quote from my previous post:

//Mapping follows: Y = (X-minRangeOld)/(maxRangeOld-minRangeOld) * (maxRangeNew-minRangeNew) + minRangeNew

just implement that in QML if you don't want to use the c++/template

---

function mapToRange(x, maxRangeOld, minRangeOld,maxRangeNew, minRangeNew)
    {
        return (x-minRangeOld)/(maxRangeOld-minRangeOld) * (maxRangeNew-minRangeNew) + minRangeNew
    }


CircularSlider {
           id: barometer
           width: 400
           height: width
           interactive: false
           minValue:    -130
           maxValue:    130
           startAngle:  -130
           endAngle:    130
           anchors.centerIn: parent
           value:  0
           //Mapping follows: Y = (X-minRangeOld)/(maxRangeOld-minRangeOld) * (maxRangeNew-minRangeNew) + minRangeNew
           angle: mapToRange(value,1070, 970, 130, -130)

....

[Markkyboy]

@J-Hilk said in Weather data value to rotation:

//Mapping follows: Y = (X-minRangeOld)/(maxRangeOld-minRangeOld) * (maxRangeNew-minRangeNew) + minRangeNew

So close, but I now get; ReferenceError: ivalue is not defined

[J.Hilk]

@Markkyboy please, you should by able to fix my typo 😅

[Markkyboy]

@J-Hilk - sorry, scrap that last comment, I changed it to value and now it works!, yay!!, thank you @J-Hilk, you sir are a genius!! :)