23dfcca431 2011-02-23        kinaba: //-------------------------------------------------------------
23dfcca431 2011-02-23        kinaba: // ccw
23dfcca431 2011-02-23        kinaba: //
23dfcca431 2011-02-23        kinaba: // Verified by
23dfcca431 2011-02-23        kinaba: //   - SRM 492 Div1 LV1
23dfcca431 2011-02-23        kinaba: //-------------------------------------------------------------
23dfcca431 2011-02-23        kinaba: 
23dfcca431 2011-02-23        kinaba: double outer_prod(const CMP& a, const CMP& b) { return imag(conj(a)*b); }
23dfcca431 2011-02-23        kinaba: double inner_prod(const CMP& a, const CMP& b) { return real(conj(a)*b); }
23dfcca431 2011-02-23        kinaba: 
23dfcca431 2011-02-23        kinaba: int ccw(const CMP& a, CMP b, CMP c) {
23dfcca431 2011-02-23        kinaba: 	b -= a; c -= a;
23dfcca431 2011-02-23        kinaba: 	if( outer_prod(b,c) > 0 ) return +1; // counter clockwise
23dfcca431 2011-02-23        kinaba: 	if( outer_prod(b,c) < 0 ) return -1; // clockwise
23dfcca431 2011-02-23        kinaba: 	if( inner_prod(b,c) < 0 ) return +2; // c--[a--b] on line
23dfcca431 2011-02-23        kinaba: 	if( norm(b) < norm(c) )   return -2; // [a--b]--c on line
23dfcca431 2011-02-23        kinaba: 	return 0; // [a--c--b] on line
23dfcca431 2011-02-23        kinaba: }