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Testing segment intersection with extent

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If needed, this function can be modified to take two additional coorinates that will be set to the intersection points.
This commit is contained in:
Tim Schaub
2014-02-22 18:39:04 -07:00
parent cb11959f01
commit 6b018bbaf9
2 changed files with 178 additions and 0 deletions
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53
src/ol/extent.js
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@@ -643,6 +643,59 @@ ol.extent.scaleFromCenter = function(extent, value) {
};
/**
* Determine if the segment between two coordinates intersects (crosses,
* touches, or is contained by) the provided extent.
* @param {ol.Extent} extent The extent.
* @param {ol.Coordinate} start Segment start coordinate.
* @param {ol.Coordinate} end Segment end coordinate.
* @return {boolean} The segment intersects the extent.
*/
ol.extent.segmentIntersects = function(extent, start, end) {
var intersects = false;
var startRel = ol.extent.coordinateRelationship(extent, start);
var endRel = ol.extent.coordinateRelationship(extent, end);
if (startRel === ol.extent.Relationship.INTERSECTING ||
endRel === ol.extent.Relationship.INTERSECTING) {
intersects = true;
} else {
var minX = extent[0];
var minY = extent[1];
var maxX = extent[2];
var maxY = extent[3];
var startX = start[0];
var startY = start[1];
var endX = end[0];
var endY = end[1];
var slope = (endY - startY) / (endX - startX);
var x, y;
if (!!(endRel & ol.extent.Relationship.ABOVE) &&
!(startRel & ol.extent.Relationship.ABOVE)) {
// potentially intersects top
x = endX - ((endY - maxY) / slope);
intersects = x >= minX && x <= maxX;
} else if (!!(endRel & ol.extent.Relationship.RIGHT) &&
!(startRel & ol.extent.Relationship.RIGHT)) {
// potentially intersects right
y = endY - ((endX - maxX) * slope);
intersects = y >= minY && y <= maxY;
} else if (!!(endRel & ol.extent.Relationship.BELOW) &&
!(startRel & ol.extent.Relationship.BELOW)) {
// potentially intersects bottom
x = endX - ((endY - minY) / slope);
intersects = x >= minX && x <= maxX;
} else if (!!(endRel & ol.extent.Relationship.LEFT) &&
!(startRel & ol.extent.Relationship.LEFT)) {
// potentially intersects left
y = endY - ((endX - minX) * slope);
intersects = y >= minY && y <= maxY;
}
}
return intersects;
};
/**
* @param {ol.Extent} extent1 Extent 1.
* @param {ol.Extent} extent2 Extent 2.