question: public static Vec4 intersect ( Plane pa , Plane pb , Plane pc ) { if ( pa == null || pb == null || pc == null ) { throw new IllegalArgumentException ( "Plane Is Null" ) ; } Vec4 na = pa . getNormal ( ) ; Vec4 nb = pb . getNormal ( ) ; Vec4 nc = pc . getNormal ( ) ; Matrix m = new Matrix ( na . x , na . y , na . z , 0 , nb . x , nb . y , nb . z , 0 , nc . x , nc . y , nc . z , 0 , 0 , 0 , 0 , 1 , true ) ; Matrix mInverse = m . getInverse ( ) ; Vec4 D = new Vec4 ( - pa . getDistance ( ) , - pb . getDistance ( ) , - pc . getDistance ( ) ) ; return D . transformBy3 ( mInverse ) ; }
target:  Compute the intersection of three planes.