added test for intersectSphere(sphere) method

test/unit/math/Ray.js

@@ -108,6 +108,53 @@ test( "isIntersectionSphere", function() {
 	ok( ! a.isIntersectionSphere( f ), "Passed!" );
 });
 
+test( "intersectSphere", function() {
+	
+	var TOL = 0.0001;
+	
+	// ray origin located at ( 0, 0, 0 ) and points outward in negative-z direction
+	var a = new THREE.Ray( zero3.clone(), new THREE.Vector3( 0, 0, -1 ) );
+
+	// sphere (radius of 2) located behind ray, should result in null
+	var b = new THREE.Sphere( new THREE.Vector3( 0, 0, 1 ), 2 );
+	ok( a.intersectSphere( b ) === null, "Passed!" );
+	
+	// sphere (radius of 2) located in front of, but too far right of ray, should result in null
+	var b = new THREE.Sphere( new THREE.Vector3( 3, 0, -1 ), 2 );
+	ok( a.intersectSphere( b ) === null, "Passed!" );
+	
+	// sphere (radius of 2) located in front of, but too far left of ray, should result in null
+	var b = new THREE.Sphere( new THREE.Vector3( -3, 0, -1 ), 2 );
+	ok( a.intersectSphere( b ) === null, "Passed!" );
+	
+	// sphere (radius of 2) located in front of, but too far above the ray, should result in null
+	var b = new THREE.Sphere( new THREE.Vector3( 0, 3, -1 ), 2 );
+	ok( a.intersectSphere( b ) === null, "Passed!" );
+	
+	// sphere (radius of 2) located in front of, but too far below the ray, should result in null
+	var b = new THREE.Sphere( new THREE.Vector3( 0, -3, -1 ), 2 );
+	ok( a.intersectSphere( b ) === null, "Passed!" );
+	
+	// sphere (radius of 1) located in front of ray, should result in intersection at 0, 0, -1 
+	var b = new THREE.Sphere( new THREE.Vector3( 0, 0, -2 ), 1 );
+	ok( a.intersectSphere( b ).distanceTo( new THREE.Vector3( 0, 0, -1 ) ) < TOL, "Passed!" );
+	
+	// sphere (radius of 2) located in front & right of ray, should result in intersection at 0, 0, -1, or left-most edge of sphere 
+	var b = new THREE.Sphere( new THREE.Vector3( 2, 0, -1 ), 2 );
+	ok( a.intersectSphere( b ).distanceTo( new THREE.Vector3( 0, 0, -1 ) ) < TOL, "Passed!" );
+	
+	// same situation as above, but move the sphere a fraction more to the right, and ray should now just miss 
+	var b = new THREE.Sphere( new THREE.Vector3( 2.01, 0, -1 ), 2 );
+	ok( a.intersectSphere( b ) === null, "Passed!" );
+	
+	// sphere (radius of 1) center located at ray origin / sphere surrounds ray origin, should result in intersection at 0, 0, 1, or entrance point on front of sphere, but behind ray
+	// if exit point on sphere ( 0, 0, -1 ) is desired in this rare situation, commented lines in Ray.js 'intersectSphere' method will need to be uncommented,
+	// and exit point on back of sphere will be returned instead.
+	var b = new THREE.Sphere( zero3.clone(), 1 );
+	ok( a.intersectSphere( b ).distanceTo( new THREE.Vector3( 0, 0, 1 ) ) < TOL, "Passed!" );
+	
+});
+
 test( "isIntersectionPlane", function() {
 	var a = new THREE.Ray( one3.clone(), new THREE.Vector3( 0, 0, 1 ) );