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Simplified wrapX handling

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"Unwrap" the coordinates obtained from transformations and utilize wrapX
capabilities of the sources to handle calculations of TileRanges and
unwrapped tile extents.
This commit is contained in:
Petr Sloup
2015-10-16 09:18:55 +02:00
parent 52a7c5e582
commit a7cde96056
3 changed files with 67 additions and 168 deletions
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src/ol/reproj/triangulation.js
+49 -55
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@@ -75,12 +75,6 @@ ol.reproj.Triangulation = function(sourceProj, targetProj, targetExtent,
*/
this.triangles_ = [];
/**
* @type {ol.Extent}
* @private
*/
this.trianglesSourceExtent_ = null;
/**
* Indicates that source coordinates have to be shifted during reprojection.
* This is needed when the triangulation crosses
@@ -129,6 +123,49 @@ ol.reproj.Triangulation = function(sourceProj, targetProj, targetExtent,
sourceTopLeft, sourceTopRight, sourceBottomRight, sourceBottomLeft,
ol.RASTER_REPROJECTION_MAX_SUBDIVISION);
if (this.wrapsXInSource_) {
// Fix coordinates (ol.proj returns wrapped coordinates, "unwrap" here).
// This significantly simplifies the rest of the reprojection process.
goog.asserts.assert(this.sourceWorldWidth_ !== null);
var leftBound = Infinity;
this.triangles_.forEach(function(triangle, i, arr) {
leftBound = Math.min(leftBound,
triangle.source[0][0], triangle.source[1][0], triangle.source[2][0]);
});
// Shift triangles to be as close to `leftBound` as possible
// (if the distance is more than `worldWidth / 2` it can be closer.
this.triangles_.forEach(function(triangle) {
if (Math.max(triangle.source[0][0], triangle.source[1][0],
triangle.source[2][0]) - leftBound > this.sourceWorldWidth_ / 2) {
var newTriangle = [[triangle.source[0][0], triangle.source[0][1]],
[triangle.source[1][0], triangle.source[1][1]],
[triangle.source[2][0], triangle.source[2][1]]];
if ((newTriangle[0][0] - leftBound) > this.sourceWorldWidth_ / 2) {
newTriangle[0][0] -= this.sourceWorldWidth_;
}
if ((newTriangle[1][0] - leftBound) > this.sourceWorldWidth_ / 2) {
newTriangle[1][0] -= this.sourceWorldWidth_;
}
if ((newTriangle[2][0] - leftBound) > this.sourceWorldWidth_ / 2) {
newTriangle[2][0] -= this.sourceWorldWidth_;
}
// Rarely (if the extent contains both the dateline and prime meridian)
// the shift can in turn break some triangles.
// Detect this here and don't shift in such cases.
var minX = Math.min(
newTriangle[0][0], newTriangle[1][0], newTriangle[2][0]);
var maxX = Math.max(
newTriangle[0][0], newTriangle[1][0], newTriangle[2][0]);
if ((maxX - minX) < this.sourceWorldWidth_ / 2) {
triangle.source = newTriangle;
}
}
}, this);
}
transformInvCache = {};
};
@@ -278,66 +315,23 @@ ol.reproj.Triangulation.prototype.addQuad_ = function(a, b, c, d,
/**
* Calculates extent of the 'source' coordinates from all the triangles.
* The left bound of the returned extent can be higher than the right bound,
* if the triangulation wraps X in source (see
* {@link ol.reproj.Triangulation#getWrapsXInSource}).
*
* @return {ol.Extent} Calculated extent.
*/
ol.reproj.Triangulation.prototype.calculateSourceExtent = function() {
if (this.trianglesSourceExtent_) {
return this.trianglesSourceExtent_;
}
var extent = ol.extent.createEmpty();
if (this.wrapsXInSource_) {
// although only some of the triangles are crossing the dateline,
// all coordinates need to be "shifted" to be positive
// to properly calculate the extent (and then possibly shifted back)
this.triangles_.forEach(function(triangle, i, arr) {
var src = triangle.source;
ol.extent.extendCoordinate(extent, src[0]);
ol.extent.extendCoordinate(extent, src[1]);
ol.extent.extendCoordinate(extent, src[2]);
});
this.triangles_.forEach(function(triangle, i, arr) {
goog.asserts.assert(this.sourceWorldWidth_);
var src = triangle.source;
ol.extent.extendCoordinate(extent,
[goog.math.modulo(src[0][0], this.sourceWorldWidth_), src[0][1]]);
ol.extent.extendCoordinate(extent,
[goog.math.modulo(src[1][0], this.sourceWorldWidth_), src[1][1]]);
ol.extent.extendCoordinate(extent,
[goog.math.modulo(src[2][0], this.sourceWorldWidth_), src[2][1]]);
}, this);
var sourceProjExtent = this.sourceProj_.getExtent();
var right = sourceProjExtent[2];
if (extent[0] > right) {
extent[0] -= this.sourceWorldWidth_;
}
if (extent[2] > right) {
extent[2] -= this.sourceWorldWidth_;
}
} else {
this.triangles_.forEach(function(triangle, i, arr) {
var src = triangle.source;
ol.extent.extendCoordinate(extent, src[0]);
ol.extent.extendCoordinate(extent, src[1]);
ol.extent.extendCoordinate(extent, src[2]);
});
}
this.trianglesSourceExtent_ = extent;
return extent;
};
/**
* @return {boolean} Whether the source coordinates are wrapped in X
* (the triangulation "crosses the dateline").
*/
ol.reproj.Triangulation.prototype.getWrapsXInSource = function() {
return this.wrapsXInSource_;
};
/**
* @return {Array.<ol.reproj.Triangle>} Array of the calculated triangles.
*/