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Support geojson with altitude #140

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Support geojson with altitude #140

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85 changes: 58 additions & 27 deletions src/clip.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,10 +7,15 @@ import createFeature from './feature.js';
* / | \____|____/
* | |
*
* k1 and k2 are the line coordinates
* axis: 0 for x, 1 for y
* minAll and maxAll: minimum and maximum coordinate value for all features
*/
* @param {*} features features to be clipped
* @param {*} scale scaling of the axis
* @param {*} k1 left/top edge of the given axis
* @param {*} k2 right/bottom edge of the given axis
* @param {*} axis 0 = x, 1 = y
* @param {*} minAll minimum value on the given axis for all features
* @param {*} maxAll maximum value on the given axis for all features
* @param {*} options
*/
export default function clip(features, scale, k1, k2, axis, minAll, maxAll, options) {
k1 /= scale;
k2 /= scale;
Expand All @@ -22,6 +27,7 @@ export default function clip(features, scale, k1, k2, axis, minAll, maxAll, opti

for (const feature of features) {
const geometry = feature.geometry;
const sqDist = feature.sqDist;
let type = feature.type;

const min = axis === 0 ? feature.minX : feature.minY;
Expand All @@ -35,33 +41,40 @@ export default function clip(features, scale, k1, k2, axis, minAll, maxAll, opti
}

let newGeometry = [];
let newSqDist = [];

if (type === 'Point' || type === 'MultiPoint') {
clipPoints(geometry, newGeometry, k1, k2, axis);

} else if (type === 'LineString') {
clipLine(geometry, newGeometry, k1, k2, axis, false, options.lineMetrics);
clipLine(geometry, newGeometry, sqDist, newSqDist, k1, k2, axis, false, options.lineMetrics);

} else if (type === 'MultiLineString') {
clipLines(geometry, newGeometry, k1, k2, axis, false);
clipLines(geometry, newGeometry, sqDist, newSqDist, k1, k2, axis, false);

} else if (type === 'Polygon') {
clipLines(geometry, newGeometry, k1, k2, axis, true);
clipLines(geometry, newGeometry, sqDist, newSqDist, k1, k2, axis, true);

} else if (type === 'MultiPolygon') {
for (const polygon of geometry) {
for (let i = 0; i < geometry.length; ++i) {
const polygon = geometry[i];
const sqDistPoly = sqDist[i];
const newPolygon = [];
clipLines(polygon, newPolygon, k1, k2, axis, true);
const newSqDistPoly = [];
clipLines(polygon, newPolygon, sqDistPoly, newSqDistPoly, k1, k2, axis, true);
if (newPolygon.length) {
newGeometry.push(newPolygon);
newSqDist.push(newSqDistPoly);
}
}
}

if (newGeometry.length) {
if (options.lineMetrics && type === 'LineString') {
for (const line of newGeometry) {
clipped.push(createFeature(feature.id, type, line, feature.tags));
for (let i = 0; i < newGeometry.length; ++i) {
const line = newGeometry[i];
const lineSqDist = newSqDist[i];
clipped.push(createFeature(feature.id, type, line, lineSqDist, feature.tags));
}
continue;
}
Expand All @@ -70,6 +83,7 @@ export default function clip(features, scale, k1, k2, axis, minAll, maxAll, opti
if (newGeometry.length === 1) {
type = 'LineString';
newGeometry = newGeometry[0];
newSqDist = newSqDist[0];
} else {
type = 'MultiLineString';
}
Expand All @@ -78,7 +92,7 @@ export default function clip(features, scale, k1, k2, axis, minAll, maxAll, opti
type = newGeometry.length === 3 ? 'Point' : 'MultiPoint';
}

clipped.push(createFeature(feature.id, type, newGeometry, feature.tags));
clipped.push(createFeature(feature.id, type, newGeometry, newSqDist, feature.tags));
}
}

Expand All @@ -95,55 +109,65 @@ function clipPoints(geom, newGeom, k1, k2, axis) {
}
}

function clipLine(geom, newGeom, k1, k2, axis, isPolygon, trackMetrics) {
function clipLine(geom, newGeom, sqDist, newSqDist, k1, k2, axis, isPolygon, trackMetrics) {

let slice = newSlice(geom);
let sqDistSlice = [];
const intersect = axis === 0 ? intersectX : intersectY;
let len = geom.start;
let segLen, t;

for (let i = 0; i < geom.length - 3; i += 3) {
const s = sqDist[i / 3];
const ax = geom[i];
const ay = geom[i + 1];
const az = geom[i + 2];
const bx = geom[i + 3];
const by = geom[i + 4];
const bz = geom[i + 5];
const a = axis === 0 ? ax : ay;
const b = axis === 0 ? bx : by;
let exited = false;

if (trackMetrics) segLen = Math.sqrt(Math.pow(ax - bx, 2) + Math.pow(ay - by, 2));

if (a < k1) {
// ---|--> | (line enters the clip region from the left)
// ---|--> | (line enters the clip region from the left/top)
if (b > k1) {
t = intersect(slice, ax, ay, bx, by, k1);
t = intersect(slice, ax, ay, az, bx, by, bz, k1);
if (trackMetrics) slice.start = len + segLen * t;
sqDistSlice.push(1);
}
} else if (a > k2) {
// | <--|--- (line enters the clip region from the right)
// | <--|--- (line enters the clip region from the right/bottom)
if (b < k2) {
t = intersect(slice, ax, ay, bx, by, k2);
t = intersect(slice, ax, ay, az, bx, by, bz, k2);
if (trackMetrics) slice.start = len + segLen * t;
sqDistSlice.push(1);
}
} else {
addPoint(slice, ax, ay, az);
sqDistSlice.push(s);
}
if (b < k1 && a >= k1) {
// <--|--- | or <--|-----|--- (line exits the clip region on the left)
t = intersect(slice, ax, ay, bx, by, k1);
t = intersect(slice, ax, ay, az, bx, by, bz, k1);
sqDistSlice.push(1);
exited = true;
}
if (b > k2 && a <= k2) {
// | ---|--> or ---|-----|--> (line exits the clip region on the right)
t = intersect(slice, ax, ay, bx, by, k2);
t = intersect(slice, ax, ay, az, bx, by, bz, k2);
sqDistSlice.push(1);
exited = true;
}

if (!isPolygon && exited) {
if (trackMetrics) slice.end = len + segLen * t;
newGeom.push(slice);
newSqDist.push(sqDistSlice);
slice = newSlice(geom);
sqDistSlice = [];
}

if (trackMetrics) len += segLen;
Expand All @@ -155,17 +179,22 @@ function clipLine(geom, newGeom, k1, k2, axis, isPolygon, trackMetrics) {
const ay = geom[last + 1];
const az = geom[last + 2];
const a = axis === 0 ? ax : ay;
if (a >= k1 && a <= k2) addPoint(slice, ax, ay, az);
if (a >= k1 && a <= k2) {
addPoint(slice, ax, ay, az);
sqDistSlice.push(1);
}

// close the polygon if its endpoints are not the same after clipping
last = slice.length - 3;
if (isPolygon && last >= 3 && (slice[last] !== slice[0] || slice[last + 1] !== slice[1])) {
addPoint(slice, slice[0], slice[1], slice[2]);
sqDistSlice.push(1);
}

// add the final slice
if (slice.length) {
newGeom.push(slice);
newSqDist.push(sqDistSlice);
}
}

Expand All @@ -177,24 +206,26 @@ function newSlice(line) {
return slice;
}

function clipLines(geom, newGeom, k1, k2, axis, isPolygon) {
for (const line of geom) {
clipLine(line, newGeom, k1, k2, axis, isPolygon, false);
function clipLines(geom, newGeom, sqDist, newSqDist, k1, k2, axis, isPolygon) {
for (let i = 0; i < geom.length; ++i) {
const lineGeom = geom[i];
const lineSqDist = sqDist[i];
clipLine(lineGeom, newGeom, lineSqDist, newSqDist, k1, k2, axis, isPolygon, false);
}
}

function addPoint(out, x, y, z) {
out.push(x, y, z);
}

function intersectX(out, ax, ay, bx, by, x) {
function intersectX(out, ax, ay, az, bx, by, bz, x) {
const t = (x - ax) / (bx - ax);
addPoint(out, x, ay + (by - ay) * t, 1);
addPoint(out, x, ay + (by - ay) * t, az + (bz - az) * t);
return t;
}

function intersectY(out, ax, ay, bx, by, y) {
function intersectY(out, ax, ay, az, bx, by, bz, y) {
const t = (y - ay) / (by - ay);
addPoint(out, ax + (bx - ax) * t, y, 1);
addPoint(out, ax + (bx - ax) * t, y, az + (bz - az) * t);
return t;
}
47 changes: 33 additions & 14 deletions src/convert.js
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@ function convertFeature(features, geojson, options, index) {
const type = geojson.geometry.type;
const tolerance = Math.pow(options.tolerance / ((1 << options.maxZoom) * options.extent), 2);
let geometry = [];
let sqDist = []; // squared distances for simplification
let id = geojson.id;
if (options.promoteId) {
id = geojson.properties[options.promoteId];
Expand All @@ -44,29 +45,32 @@ function convertFeature(features, geojson, options, index) {
}

} else if (type === 'LineString') {
convertLine(coords, geometry, tolerance, false);
convertLine(coords, geometry, sqDist, tolerance, false);

} else if (type === 'MultiLineString') {
if (options.lineMetrics) {
// explode into linestrings to be able to track metrics
for (const line of coords) {
geometry = [];
convertLine(line, geometry, tolerance, false);
sqDist = [];
convertLine(line, geometry, sqDist, tolerance, false);
features.push(createFeature(id, 'LineString', geometry, geojson.properties));
}
return;
} else {
convertLines(coords, geometry, tolerance, false);
convertLines(coords, geometry, sqDist, tolerance, false);
}

} else if (type === 'Polygon') {
convertLines(coords, geometry, tolerance, true);
convertLines(coords, geometry, sqDist, tolerance, true);

} else if (type === 'MultiPolygon') {
for (const polygon of coords) {
const newPolygon = [];
convertLines(polygon, newPolygon, tolerance, true);
const newSqDist = [];
convertLines(polygon, newPolygon, newSqDist, tolerance, true);
geometry.push(newPolygon);
sqDist.push(newSqDist);
}
} else if (type === 'GeometryCollection') {
for (const singleGeometry of geojson.geometry.geometries) {
Expand All @@ -81,22 +85,33 @@ function convertFeature(features, geojson, options, index) {
throw new Error('Input data is not a valid GeoJSON object.');
}

features.push(createFeature(id, type, geometry, geojson.properties));
features.push(createFeature(id, type, geometry, sqDist, geojson.properties));
}

function convertPoint(coords, out) {
out.push(projectX(coords[0]), projectY(coords[1]), 0);
out.push(projectX(coords[0]), projectY(coords[1]));

if (coords.length > 2) {
out.push(coords[2]);
} else {
out.push(0);
}
}

function convertLine(ring, out, tolerance, isPolygon) {
function convertLine(ring, out, sqDist, tolerance, isPolygon) {
let x0, y0;
let size = 0;

for (let j = 0; j < ring.length; j++) {
const x = projectX(ring[j][0]);
const y = projectY(ring[j][1]);

out.push(x, y, 0);
out.push(x, y);
if (ring[j].length > 2) {
out.push(ring[j][2]);
} else {
out.push(0);
}

if (j > 0) {
if (isPolygon) {
Expand All @@ -110,20 +125,24 @@ function convertLine(ring, out, tolerance, isPolygon) {
}

const last = out.length - 3;
out[2] = 1;
simplify(out, 0, last, tolerance);
out[last + 2] = 1;
sqDist.length = out.length / 3;
sqDist.fill(0);
sqDist[0] = 1;
simplify(sqDist, out, 0, last, tolerance);
sqDist[last / 3] = 1;

out.size = Math.abs(size);
out.start = 0;
out.end = out.size;
}

function convertLines(rings, out, tolerance, isPolygon) {
function convertLines(rings, out, outSqDist, tolerance, isPolygon) {
for (let i = 0; i < rings.length; i++) {
const geom = [];
convertLine(rings[i], geom, tolerance, isPolygon);
const sqDist = [];
convertLine(rings[i], geom, sqDist, tolerance, isPolygon);
out.push(geom);
outSqDist.push(sqDist);
}
}

Expand Down
3 changes: 2 additions & 1 deletion src/feature.js
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Original file line number Diff line number Diff line change
@@ -1,9 +1,10 @@

export default function createFeature(id, type, geom, tags) {
export default function createFeature(id, type, geom, sqDist, tags) {
const feature = {
id: id == null ? null : id,
type,
geometry: geom,
sqDist,
tags,
minX: Infinity,
minY: Infinity,
Expand Down
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