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Set elevation on points without it (workaround for bug in Leaflet.Heightgraph)

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alexcojocaru 2020-11-11 13:22:05 -08:00
parent f1d2855dca
commit d83fddd4ed
1 changed files with 159 additions and 9 deletions
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168
js/plugin/Heightgraph.js
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@ -60,6 +60,14 @@ BR.Heightgraph = function(map, layersControl, routing, pois) {
// extra options
shortcut: {
toggle: 69 // char code for 'e'
},
patches: {
// whether or not to compensate for the bug in Leaflet.Heightgraph
// which makes the chart rendering to break if the track contains points
// without an elevation/altitude coordinate;
// if set to true, the elevation of these points will be inferred
// from the adjacent points which have it
inferElevation: true
}
},
@ -219,14 +227,10 @@ BR.Heightgraph = function(map, layersControl, routing, pois) {
segments.forEach(function(segment) {
var currentGradient = self._calculateGradient(segment);
if (typeof currentGradient === 'undefined') {
// not enough points on the segment to calculate the gradient
currentFeature = self._buildFeature(segment, currentGradient);
features.push(currentFeature);
} else if (currentGradient == previousGradient) {
if (currentGradient == previousGradient) {
// the gradient hasn't changed, we can append this segment to the last feature;
// since the segment contains, at index 0 the last point on the feature,
// add only points from index 1 onward
// since the segment contains, at index 0,
// the last point on the current feature, add only points from index 1 onward
self._addPointsToFeature(currentFeature, segment.slice(1));
} else {
// the gradient has changed; create a new feature
@ -378,15 +382,17 @@ BR.Heightgraph = function(map, layersControl, routing, pois) {
* Add the given array of LatLng points to the end of the provided feature.
*/
_addPointsToFeature: function(feature, latLngs) {
latLngs.forEach(function(point) {
var latLngsWithElevation = this._inferElevation(latLngs);
latLngsWithElevation.forEach(function(point) {
var coordinate = [point.lng, point.lat, point.alt];
feature.geometry.coordinates.push(coordinate);
});
},
_buildFeature: function(latLngs, gradient) {
var latLngsWithElevation = this._inferElevation(latLngs);
var coordinates = [];
latLngs.forEach(function(latLng) {
latLngsWithElevation.forEach(function(latLng) {
coordinates.push([latLng.lng, latLng.lat, latLng.alt]);
});
@ -402,6 +408,147 @@ BR.Heightgraph = function(map, layersControl, routing, pois) {
};
},
/**
* If the global flag is true, return a new list of LatLng points
* which all have the elevation coordinate set,
* so that the overall gradient profile of the point list stays the same.
* If there are points without elevation at the start or end of the given list,
* the elevation coordinate is set so that the gradient profile to the closest point
* with elevation is flat (i.e. the gradient is 0).
* If the global flag is false, the given list is returned.
*/
_inferElevation: function(latLngs) {
if (this.options.patches.inferElevation != true || latLngs.length === 0) {
return latLngs;
}
var result = latLngs.slice();
this._inferElevationStart(result);
this._inferElevationEnd(result);
// find points without elevation and set it
var previousIndex = -1; // keep track of the index of the previous point with elevation
for (var i = 0; i < result.length; i++) {
if (typeof result[i].alt !== 'undefined') {
previousIndex = i;
continue;
}
// we've just found the first point in a potential series
// if there is no previous point with elevation (which is unexpected),
// we're in a pickle, hence skip the current point
if (previousIndex == -1) {
continue;
}
// look up the next point with ele
var nextIndex = i + 1;
for (; nextIndex < result.length; nextIndex++) {
if (typeof result[nextIndex].alt !== 'undefined') {
break;
}
}
// if we got to the end of list and haven't found a point with elevation
// (which is unexpected), we're in a pickle, hence skip the current point
if (nextIndex == result.length) {
continue;
}
// fix the elevation on all points in the current series
this._inferElevationSublist(result, previousIndex + 1, nextIndex - 1);
// finally, since we've fixed the current series, skip to the next point
i = nextIndex - 1;
}
return result;
},
/*
* Check for points without elevation at the start of the list;
* if such points are found, set their elevation to be the same
* as the elevation on the first point with such coordinate.
* If no points in the list have an elevation coordinate, set it to 0 on all.
* Note that the given list of LatLng points is mutated.
*/
_inferElevationStart: function(latLngs) {
// if the list is empty, or the first point has elevation, there's nothing to do
if (latLngs.length == 0 || typeof latLngs[0].alt !== 'undefined') {
return;
}
var index = 0; // the index of the first point with elevation
var alt = 0; // the elevation of the first point with such coordinate
for (; index < latLngs.length; index++) {
if (typeof latLngs[index].alt !== 'undefined') {
alt = latLngs[index].alt;
break;
}
}
// set the elevation on all points without it at the start of the list
for (var i = 0; i < index; i++) {
var point = latLngs[i];
latLngs[i] = L.latLng(point.lat, point.lng, alt);
}
},
/*
* Check for points without elevation at the end of the list;
* if such points are found, set their elevation to be the same
* as the elevation on the last point with such coordinate.
* If no points in the list have an elevation coordinate, set it to 0 on all.
* Note that the given list of LatLng points is mutated.
*/
_inferElevationEnd: function(latLngs) {
// if the list is empty, or the last point has elevation, there's nothing to do
if (latLngs.length == 0 || typeof latLngs[latLngs.length - 1].alt !== 'undefined') {
return;
}
var index = latLngs.length - 1; // the index of the last point with elevation
var alt = 0; // the elevation of the last point with such coordinate
for (; index >= 0; index--) {
if (typeof latLngs[index].alt !== 'undefined') {
alt = latLngs[index].alt;
break;
}
}
// set the elevation on all points without it at the end of the list
for (var i = index + 1; i < latLngs.length; i++) {
var point = latLngs[i];
latLngs[i] = L.latLng(point.lat, point.lng, alt);
}
},
/**
* Given the list of LatLng points,
* and the series of points without elevation from startIndex to endIndex,
* set the elevation on these points so that the gradient from
* startIndex-1 to endIndex+1 is constant.
* startIndex must be preceeded by a point with elevation;
* endIndex must be followed by a point with elevation.
* Note that the given list of LatLng points is mutated.
*/
_inferElevationSublist: function(latLngs, startIndex, endIndex) {
var previousIndex = startIndex - 1; // index of the previous point with elevation before this series
var nextIndex = endIndex + 1; // index of the next point with elevation after this series
// calculate the overall gradient for the current series
var distance = this._calculateDistance(latLngs.slice(previousIndex, nextIndex + 1));
var altitudeDelta = latLngs[nextIndex].alt - latLngs[previousIndex].alt;
var gradient = distance == 0 ? 0 : (altitudeDelta * 100) / distance;
// now fix the elevation on each point in the series, one by one
for (var i = startIndex; i <= endIndex; i++) {
var dist = latLngs[i].distanceTo(latLngs[i - 1]);
var alt = (gradient * dist) / 100 + latLngs[i - 1].alt;
var point = latLngs[i];
latLngs[i] = L.latLng(point.lat, point.lng, Number(alt.toFixed(1)));
}
},
/**
* Map a gradient percentage to one of the levels defined
* in options.mappings.gradient.
@ -429,6 +576,9 @@ BR.Heightgraph = function(map, layersControl, routing, pois) {
return 4;
} else if (gradientPercentage >= 16) {
return 5;
} else {
console.log('Unknown gradientPercentage: ', gradientPercentage, '; cannot map');
return 0;
}
}
});