Code of Cohen-Sutherland Algoritm for Line Clipping in C++ Programming language

cohen-sutherland-algorithm.cp

// Cohen–Sutherland Algorithm
bool clip(point &A, point &B, point Pmin, point Pmax) {
	while (true) {
		unsigned int C1 = 0;
		if (A.x < Pmin.x) C1 += 1;
		if (A.x > Pmax.x) C1 += 2;
		if (A.y < Pmin.y) C1 += 4;
		if (A.y > Pmax.y) C1 += 8;

		unsigned int C2 = 0;
		if (B.x < Pmin.x) C2 += 1;
		if (B.x > Pmax.x) C2 += 2;
		if (B.y < Pmin.y) C2 += 4;
		if (B.y > Pmax.y) C2 += 8;

		if ((C1 == C2) && (C1 == 0)) return true;

		if ((C1 & C2) != 0) return false;

		if (C1 == 0) {
			std::swap(A, B);
		}

		if ((C1 & 1) != 0) {
			A.y = B.y - (B.x - Pmin.x) * (B.y - A.y) / (B.x - A.x);
			A.x = Pmin.x;
		} else if ((C1 & 2) != 0) {
			A.y = B.y - (B.x - Pmax.x) * (B.y - A.y) / (B.x - A.x);
			A.x = Pmax.x;
		} else if ((C1 & 4) != 0) {
			A.x = B.x - (B.y - Pmin.y) * (B.x - A.x) / (B.y - A.y);
			A.y = Pmin.y;
		} else if ((C1 & 8) != 0) {
			A.x = B.x - (B.y - Pmax.y) * (B.x - A.x) / (B.y - A.y);
			A.y = Pmax.y;
		}
	}
}