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Add Line class to basics.

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This commit is contained in:
Jürg Lehni 2011-03-06 14:45:07 +00:00
parent 8be1041011
commit 15b16aaed9
1 changed files with 50 additions and 0 deletions
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src/basic/Line.js Normal file
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var Line = this.Line = Base.extend({
initialize: function(point1, point2, infinite) {
// Convention: With 3 parameters, both points are absolute, and infinite
// controls wether the line extends beyond the defining points, meaning
// intersection outside the line segment are allowed.
// With two parameters, the 2nd parameter is a direction, and infinite
// is automatially true, since we're describing an infinite line.
point1 = Point.read(arguments, 0, 1);
point2 = Point.read(arguments, 1, 1);
if (arguments.length == 3) {
this.point = point1;
this.vector = point2.subtract(point1);
this.infinite = infinite;
} else {
this.point = point1;
this.vector = point2;
this.infinite = true;
}
},
intersect: function(line) {
var cross = this.vector.cross(line.vector);
// Epsilon tolerance
if (Math.abs(cross) <= 10e-6)
return null;
var v = line.point.subtract(this.point)
t1 = v.cross(line.vector) / cross,
t2 = v.cross(this.vector) / cross;
// Check the ranges of t parameters if the line is not allowed to
// extend beyond the definition points.
return (this.infinite || 0 <= t1 && t1 <= 1)
&& (line.infinite || 0 <= t2 && t2 <= 1)
? this.point.add(this.vector.multiply(t1)) : null;
},
getSide: function(p) {
var v1 = this.vector,
v2 = p.subtract(this.point),
ccw = v2.cross(v1);
if (ccw == 0.0) {
ccw = v2.dot(v1);
if (ccw > 0.0) {
ccw = (v2 - v1).dot(v1);
if (ccw < 0.0)
ccw = 0.0;
}
}
return ccw < 0.0 ? -1 : ccw > 0.0 ? 1 : 0;
}
});