Snippets writing apps with gyroscope and GPS

angleBetweenVectorAndPlane.js

function getAngleBetweenVectorAndPlane(vector, plane) {
    var angle = Math.asin(Math.abs(plane.x * vector.x + plane.y * vector.y + plane.z * vector.z) / (Math.sqrt(Math.pow(plane.x, 2) + Math.pow(plane.y, 2) + Math.pow(plane.z, 2)) * Math.sqrt(Math.pow(vector.x, 2) + Math.pow(vector.y, 2) + Math.pow(vector.z, 2))));
    // http://www.vitutor.com/geometry/distance/line_plane.html        
    var direction = -vector.z / Math.abs(vector.z); // Because vector angle is always shortest and has no direction
    angle = angle * direction * 180 / Math.PI;
    return angle;
}

example.html

<script src="../js/gyronorm.complete.min.js" type="text/javascript"></script>

<script>
gn.init().then(function() {
            gn.start(function(data) {
                var calculation = processSensorData(-data.dm.gx, data.dm.gy, data.dm.gz, data.do.alpha, data.do.beta, data.do.gamma);
                updateInterface(calculation.rotationX, calculation.rotationZ, calculation.viewDistance);
            });
        }).catch(function(e) {
            // Catch if the DeviceOrientation or DeviceMotion is not supported by the browser or device
        });

function processSensorData(accelerationIncludingGravityX, accelerationIncludingGravityY, accelerationIncludingGravityZ, alpha, beta, gamma) {
    var plane = {
        "x": 0,
        "y": 0,
        "z": 1
    }

    var deviceRotationVector = {
        "x": accelerationIncludingGravityX,
        "y": accelerationIncludingGravityY,
        "z": accelerationIncludingGravityZ
    }

    var viewAngle = getAngleBetweenVectorAndPlane(deviceRotationVector, plane);

    var compassHeading = getCompassHeading(alpha, beta, gamma);
    var viewDistance = getViewDistance(viewAngle);
    var phoneTilt = Math.atan2(deviceRotationVector.y, deviceRotationVector.x) * 180 / Math.PI + 90;

    var calculations = {
        "rotationY": viewAngle,
        "rotationX": compassHeading,
        "rotationZ": phoneTilt,
        "viewDistance": viewDistance
    }

    return calculations;
}
</script>

getCompassHeading.js

function getCompassHeading(alpha, beta, gamma) {
    // https://stackoverflow.com/questions/18112729/calculate-compass-heading-from-deviceorientation-event-api

    // Convert degrees to radians
    var alphaRad = alpha * (Math.PI / 180);
    var betaRad = beta * (Math.PI / 180);
    var gammaRad = gamma * (Math.PI / 180);

    // Calculate equation components
    var cA = Math.cos(alphaRad);
    var sA = Math.sin(alphaRad);
    var cB = Math.cos(betaRad);
    var sB = Math.sin(betaRad);
    var cG = Math.cos(gammaRad);
    var sG = Math.sin(gammaRad);

    // Calculate A, B, C rotation components
    var rA = -cA * sG - sA * sB * cG;
    var rB = -sA * sG + cA * sB * cG;
    var rC = -cB * cG;

    // Calculate compass heading
    var compassHeading = Math.atan(rA / rB);

    // Convert from half unit circle to whole unit circle
    if (rB < 0) {
        compassHeading += Math.PI;
    } else if (rA < 0) {
        compassHeading += 2 * Math.PI;
    }

    // Convert radians to degrees
    compassHeading *= 180 / Math.PI;
    if (compassHeading < -180) {
        compassHeading += 360;
    }
    if (compassHeading > 180) {
        compassHeading -= 360;
    }

    return compassHeading;
}

getViewDistance.js

function getViewDistance(verticalAngleInDegree, altitudeInM) {
    verticalAngleInDegree = 90 - verticalAngleInDegree;
    var defaultAltitude = 1.8; // Your eyes above ground
    altitudeInM = altitudeInM || defaultAltitude; //m
    if (verticalAngleInDegree > 90) {
        return 999999999999999; // You are looking above to horizon
    } else {
        // https://www.matheretter.de/formeln/geometrie/dreieckrw/
        var distance = Math.tan(verticalAngleInDegree / 180 * Math.PI) * altitudeInM;
        return distance;
    }
}