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- Added a method to get the point of intersection.

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- Added getLength().
- Took out crazy null-tolerance in equals(). If your line is malformed,
  you may get NPE's trying to test equality with another line. Fix your line.

These are line segments anyway. We should maybe rename this
class to LineSegment.


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@4702 542714f4-19e9-0310-aa3c-eee0fc999fb1
This commit is contained in:
Ray Greenwell
2007-05-09 00:26:14 +00:00
parent ef43b9d41a
commit 5b07cd55f9
1 changed files with 56 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/as/com/threerings/util/Line.as
+56 -35
View File
@@ -42,11 +42,27 @@ public class Line implements Equalable
this.stop = stop;
}
/**
* Get the length of this line.
*/
public function getLength () :Number
{
return Point.distance(start, stop);
}
public function isIntersected (line :Line) :Boolean
{
return getIntersectionType(line) != DOES_NOT_INTERSECT;
}
/**
* Return the point at which the other line intersects us.
*/
public function getIntersectionPoint (line :Line) :Point
{
return getIntersection(line, true) as Point;
}
/**
* Tests if the given line intersects this line. This method rotates both lines so that the
* start point of this line is on the left, at (0, 0). If the lines do intersect, it then
@@ -57,6 +73,28 @@ public class Line implements Equalable
* return DOES_NOT_INTERSECT.
*/
public function getIntersectionType (line :Line) :int
{
return getIntersection(line, false) as int;
}
// from interface Equalable
public function equals (o :Object) :Boolean
{
var other :Line = o as Line; // or null if not a line
if (other == null) {
return false;
}
// both end points must be the same, in the same order
return start.equals(other.start) && stop.equals(other.stop);
}
/**
* Internal method that calculates whether the other line intersects
* and returns either the intersected point or merely the intersection
* type.
*/
protected function getIntersection (line :Line, returnPoint :Boolean) :*
{
// rotate so that this line is horizontal, with the start on the left, at (0, 0)
var trans :Matrix = new Matrix();
@@ -65,50 +103,33 @@ public class Line implements Equalable
var thisLineStop :Point = trans.transformPoint(stop);
var thatLineStart :Point = trans.transformPoint(line.start);
var thatLineStop :Point = trans.transformPoint(line.stop);
var interp :Point;
var type :int;
if (thatLineStart.y >= 0 && thatLineStop.y <= 0) {
var interp :Point = Point.interpolate(thatLineStart, thatLineStop, thatLineStop.y /
interp = Point.interpolate(thatLineStart, thatLineStop, thatLineStop.y /
(thatLineStop.y + (-thatLineStart.y)));
if (interp.x >= 0 && interp.x <= thisLineStop.x) {
return INTERSECTION_NORTH;
} else {
return DOES_NOT_INTERSECT;
}
type = INTERSECTION_NORTH;
} else if (thatLineStart.y <= 0 && thatLineStop.y >= 0) {
interp = Point.interpolate(thatLineStop, thatLineStart, thatLineStart.y /
(thatLineStart.y + (-thatLineStop.y)));
if (interp.x >= 0 && interp.x <= thisLineStop.x) {
return INTERSECTION_SOUTH;
type = INTERSECTION_SOUTH;
}
// see if we have a potential hit...
if (interp != null && interp.x >= 0 && interp.x <= thisLineStop.x) {
if (returnPoint) {
// transform the intersection point back into "real" coordinates
trans.invert();
return trans.transformPoint(interp);
} else {
return DOES_NOT_INTERSECT;
}
} else {
return DOES_NOT_INTERSECT;
}
}
// from interface Equalable
public function equals (o :Object) :Boolean
{
var other :Line = o as Line;
if (other == null) {
return false;
}
if (start == null || other.start == null) {
if (start != other.start) {
// not both null
return false;
}
}
if (stop == null || other.stop == null) {
if (stop != other.stop) {
// not both null
return false;
return type
}
}
return (start == null || start.equals(other.start)) &&
(stop == null || stop.equals(other.stop));
return returnPoint ? null : DOES_NOT_INTERSECT;
}
}
}