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Add method for sphere intersections #2

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Add method for sphere intersections #2

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17 changes: 15 additions & 2 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -285,8 +285,21 @@
}

return new_rs;
}
},

// Arvo's algorithm
// Arvo, James, A Simple Method for Box-Sphere Intersection Testing, p. 335-339, code: p. 730-732, BoxSphere.c.
// solid-solid case
// `sphere` should be Array [ x, y, z, radius ]
intersectWithSphere: function( sphere ) {
var dmin = 0;
for ( var i = 0; i < this._numDimensions; i++ ) {
if ( sphere[i] < this.min[i] ) dmin += Math.pow( ( sphere[i] - this.min[i] ), 2 );
if ( sphere[i] > this.max[i] ) dmin += Math.pow( ( sphere[i] - this.max[i] ), 2 );
}
return dmin <= Math.pow( sphere[ this._numDimensions ], 2 )
}
};

return AABB;
}));
}));
18 changes: 17 additions & 1 deletion test/aabb-test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,14 @@ vows.describe('AABB').addBatch({
var t = new AABB([-6, -3], [6, 2])
assert.isFalse (aabb.contained(t));
},
'circle intersects': function( aabb ) {
var c = [ 0, 0, 1 ];
assert.isTrue( aabb.intersectWithSphere( c ) );
},
'circle does not intersect': function( aabb ) {
var c = [ 10, 10, 1 ];
assert.isFalse( aabb.intersectWithSphere( c ) );
}
},
'Testing 3D AABB': {
topic: function(){ return new AABB([-5, -2, -5], [5, 3, 5]); },
Expand Down Expand Up @@ -104,6 +112,14 @@ vows.describe('AABB').addBatch({
{a: 0, b: 0}
];
assert.isFalse (aabb.intersectWithSegment(s));
}
},
'sphere intersects': function( aabb ) {
var s = [ 0, 0, 0, 1 ];
assert.isTrue( aabb.intersectWithSphere( s ) );
},
'sphere does not intersect': function( aabb ) {
var s = [ 10, 10, 10, 1 ];
assert.isFalse( aabb.intersectWithSphere( s ) );
}
}
}).export(module);