[GIS] Get Intersection when drawing line

openlayers

I have come code: Is it possible to get coordinates of allready drawn points ? Or get intersection with other feature when drawing? 

app.current.interaction = new ol.interaction.Draw({
    features: app.current.featureOverlay.getFeatures(),
    type: featureType.drawType
});
app.current.interaction.on('drawstart', function () {
        app.current.interaction.lastEvent = 'drawstart';
    });

Best Answer

Answer moved from the question:

Here is code, which gives you all intersecion with calculation of intersected segments (native openlayers works strange it counts just beetween start coord of LineString and end coord)

app.current.interaction = new ol.interaction.Draw({
    features: app.current.featureOverlay.getFeatures(),
    type: featureType.drawType
});
app.current.interaction.on('drawstart', function () {
        app.current.interaction.lastEvent = 'drawstart';
    });

$(window.map.getViewport()).on('mousemove',function(){

window.map.getLayers().forEach(function (layer) {

                    var features = layer.getSource().getFeatures();
                    if (features.length > 0) {

                        features.forEach(function (feature) {

                            if (app.current.drawFeatureData !== null) {
                                var geom = app.current.drawFeatureData.getGeometry(); //get current drawFeature data from "startdrag" Draw event"

                                if (geom) {

                                    var drawCoords = geom.getCoordinates();
                                    var featureCoords = feature.getGeometry().getCoordinates();
                                    var index;

                                    if (drawCoords.length > 2) {
                                        index = drawCoords.length - 2;
                                    } else {
                                        index = 0;
                                    }

                                    var x1 = drawCoords[index][0];
                                    var y1 = drawCoords[index][1];
                                    var x2 = drawCoords[drawCoords.length - 1][0];
                                    var y2 = drawCoords[drawCoords.length - 1][1];

                                    feature.setStyle(app.styles.line);
                                    app.current.hasBarrierIntersection = null; // global trigger if has intersection
                                    //app.current.drawFeatureData.setStyle(...); // set style for draw feature

//get segments of LineString
                                    if (featureCoords[0].length > 0) {
                                        for (var i = 0; i < featureCoords[0].length; i++) {
                                            var firstCoord = featureCoords[0][i];
                                            var nextCoord = featureCoords[0][i + 1];
                                            if (nextCoord) {
                                                var x3 = firstCoord[0];
                                                var y3 = firstCoord[1];
                                                var x4 = nextCoord[0];
                                                var y4 = nextCoord[1];

                                                var result = app.getIntersection(x1, y1, x2, y2, x3, y3, x4, y4);

                                                if (result.line1 && result.line2) {
                                                    app.current.drawFeatureData.setStyle(app.styles.routeLineIntersected);
                                                    feature.setStyle(app.styles.lineIntersected);
                                                    app.current.hasBarrierIntersection = true;
                                                }
                                            }
                                        }
                                    }
                                }
                            }
                        });
                    }
            });
});

Here is code which counts intersection with 4 coords (i've found it on stackoverflow, can't find link):

app = {

//returns line1 = true - if line 1 intersects as infinte vector, line2 = true - if line2 intersects as infinite vector, line1 && line2 - if segments are intersected, x,y -  coords of intersection

getIntersection: function (x1, y1, x2, y2, x3, y3, x4, y4) {
        var denominator, a, b, numerator1, numerator2, result = {
            x: null,
            y: null,
            line1: false,
            line2: false
        };
        denominator = ((y4 - y3) * (x2 - x1)) - ((x4 - x3) * (y2 - y1));
        if (denominator == 0) {
            return result;
        }
        a = y1 - y3;
        b = x1 - x3;
        numerator1 = ((x4 - x3) * a) - ((y4 - y3) * b);
        numerator2 = ((x2 - x1) * a) - ((y2 - y1) * b);
        a = numerator1 / denominator;
        b = numerator2 / denominator;

        result.x = x1 + (a * (x2 - x1));
        result.y = y1 + (a * (y2 - y1));

        if (a > 0 && a < 1) {
            result.line1 = true;
        }

        if (b > 0 && b < 1) {
            result.line2 = true;
        }

        return result;
    }
}
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