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Detect and handle triangles (tiles) crossing the dateline (projection edge)

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This commit is contained in:
Petr Sloup
2015-06-02 21:39:40 +02:00
parent b221e1ac1f
commit ac76989447
3 changed files with 129 additions and 27 deletions
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87
src/ol/reproj/triangulation.js
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@@ -24,13 +24,13 @@ ol.reproj.Triangulation;
* @param {ol.Coordinate} a
* @param {ol.Coordinate} b
* @param {ol.Coordinate} c
* @param {ol.TransformFunction} transformFwd Forward transform (src -> dst).
* @param {ol.TransformFunction} transformInv Inverse transform (dst -> src).
* @param {ol.proj.Projection} sourceProj
* @param {ol.proj.Projection} targetProj
* @param {ol.Extent=} opt_maxTargetExtent
* @param {ol.Extent=} opt_maxSourceExtent
*/
ol.reproj.triangulation.addTriangleIfValid_ = function(triangulation, a, b, c,
transformFwd, transformInv, opt_maxTargetExtent, opt_maxSourceExtent) {
sourceProj, targetProj, opt_maxTargetExtent, opt_maxSourceExtent) {
if (goog.isDefAndNotNull(opt_maxTargetExtent)) {
if (!ol.extent.containsCoordinate(opt_maxTargetExtent, a) &&
!ol.extent.containsCoordinate(opt_maxTargetExtent, b) &&
@@ -43,6 +43,7 @@ ol.reproj.triangulation.addTriangleIfValid_ = function(triangulation, a, b, c,
b = ol.extent.closestCoordinate(opt_maxTargetExtent, b);
c = ol.extent.closestCoordinate(opt_maxTargetExtent, c);
}
var transformInv = ol.proj.getTransform(targetProj, sourceProj);
var aSrc = transformInv(a);
var bSrc = transformInv(b);
var cSrc = transformInv(c);
@@ -62,12 +63,56 @@ ol.reproj.triangulation.addTriangleIfValid_ = function(triangulation, a, b, c,
aSrc = ol.extent.closestCoordinate(opt_maxSourceExtent, aSrc);
bSrc = ol.extent.closestCoordinate(opt_maxSourceExtent, bSrc);
cSrc = ol.extent.closestCoordinate(opt_maxSourceExtent, cSrc);
var transformFwd = ol.proj.getTransform(sourceProj, targetProj);
a = transformFwd(aSrc);
b = transformFwd(bSrc);
c = transformFwd(cSrc);
}
}
triangulation.push([[aSrc, a], [bSrc, b], [cSrc, c]]);
var shiftDistance = 0;
if (sourceProj.isGlobal()) {
// determine if the triangle crosses the dateline here
// This can be detected by transforming centroid of the target triangle.
// If the transformed centroid is outside the transformed triangle,
// the triangle wraps around projection extent.
// In such case, the
var srcExtent = ol.extent.createEmpty();
ol.extent.extendCoordinate(srcExtent, aSrc);
ol.extent.extendCoordinate(srcExtent, bSrc);
ol.extent.extendCoordinate(srcExtent, cSrc);
var centroid = [(a[0] + b[0] + c[0]) / 3,
(a[1] + b[1] + c[1]) / 3];
var centroidSrc = transformInv(centroid);
var pInTriangle = function(p, p0, p1, p2) {
//TODO: move somewhere else
var A = (-p1[1] * p2[0] + p0[1] * (-p1[0] + p2[0]) +
p0[0] * (p1[1] - p2[1]) + p1[0] * p2[1]) / 2;
var sign = A < 0 ? -1 : 1;
var s = (p0[1] * p2[0] - p0[0] * p2[1] +
(p2[1] - p0[1]) * p[0] +
(p0[0] - p2[0]) * p[1]) * sign;
var t = (p0[0] * p1[1] - p0[1] * p1[0] +
(p0[1] - p1[1]) * p[0] +
(p1[0] - p0[0]) * p[1]) * sign;
return s > 0 && t > 0 && (s + t) < 2 * A * sign;
};
if (!pInTriangle(centroidSrc, aSrc, bSrc, cSrc)) {
var sourceProjExtent = sourceProj.getExtent();
shiftDistance = ol.extent.getWidth(sourceProjExtent);
}
}
var tri = [[aSrc, a], [bSrc, b], [cSrc, c]];
// TODO: typing ! do not add properties to arrays !
tri.shiftDistance = shiftDistance;
if (shiftDistance) {
triangulation.shiftDistance = shiftDistance;
}
triangulation.push(tri);
};
@@ -85,9 +130,6 @@ ol.reproj.triangulation.addTriangleIfValid_ = function(triangulation, a, b, c,
ol.reproj.triangulation.createForExtent = function(extent, sourceProj,
targetProj, opt_maxTargetExtent, opt_maxSourceExtent, opt_subdiv) {
var transformFwd = ol.proj.getTransform(sourceProj, targetProj);
var transformInv = ol.proj.getTransform(targetProj, sourceProj);
var triangulation = [];
var tlDst = ol.extent.getTopLeft(extent);
@@ -118,10 +160,10 @@ ol.reproj.triangulation.createForExtent = function(extent, sourceProj,
ol.reproj.triangulation.addTriangleIfValid_(
triangulation, x0y0dst, x1y1dst, x0y1dst,
transformFwd, transformInv, opt_maxTargetExtent, opt_maxSourceExtent);
sourceProj, targetProj, opt_maxTargetExtent, opt_maxSourceExtent);
ol.reproj.triangulation.addTriangleIfValid_(
triangulation, x0y0dst, x1y0dst, x1y1dst,
transformFwd, transformInv, opt_maxTargetExtent, opt_maxSourceExtent);
sourceProj, targetProj, opt_maxTargetExtent, opt_maxSourceExtent);
}
}
@@ -136,11 +178,28 @@ ol.reproj.triangulation.createForExtent = function(extent, sourceProj,
ol.reproj.triangulation.getSourceExtent = function(triangulation) {
var extent = ol.extent.createEmpty();
goog.array.forEach(triangulation, function(triangle, i, arr) {
ol.extent.extendCoordinate(extent, triangle[0][0]);
ol.extent.extendCoordinate(extent, triangle[1][0]);
ol.extent.extendCoordinate(extent, triangle[2][0]);
});
if (triangulation.shiftDistance) {
var shiftDistance = triangulation.shiftDistance;
goog.array.forEach(triangulation, function(triangle, i, arr) {
ol.extent.extendCoordinate(extent,
[goog.math.modulo(triangle[0][0][0] + shiftDistance, shiftDistance),
triangle[0][0][1]]);
ol.extent.extendCoordinate(extent,
[goog.math.modulo(triangle[1][0][0] + shiftDistance, shiftDistance),
triangle[1][0][1]]);
ol.extent.extendCoordinate(extent,
[goog.math.modulo(triangle[2][0][0] + shiftDistance, shiftDistance),
triangle[2][0][1]]);
});
if (extent[0] > shiftDistance / 2) extent[0] -= shiftDistance;
if (extent[2] > shiftDistance / 2) extent[2] -= shiftDistance;
} else {
goog.array.forEach(triangulation, function(triangle, i, arr) {
ol.extent.extendCoordinate(extent, triangle[0][0]);
ol.extent.extendCoordinate(extent, triangle[1][0]);
ol.extent.extendCoordinate(extent, triangle[2][0]);
});
}
return extent;
};