交差する線分の交点座標.cs

Vector3 p0 = new Vector3(-1,0,0);
Vector3 p1 = new Vector3(1,0,0);
Vector3 p2 = new Vector3(0,-1,0);
Vector3 p3 = new Vector3(0,1,0);
Gizmos.DrawLine(p0, p1);
Gizmos.DrawLine(p2, p3);
Vector3 pt = getCrossPoint(p0, p2, p1, p3);
Gizmos.DrawWireSphere( pt, 0.1f);

// http://imagingsolution.blog107.fc2.com/blog-entry-137.html
// http://www.mztm.jp/2010/08/05/clossline/
Vector3 getCrossPoint(Vector3 P1, Vector3 P2, Vector3 P3, Vector3 P4){
	float S1 = ((P4.x-P2.x)*(P1.y-P2.y)-(P4.y-P2.y)*(P1.x-P2.x))*0.5f;
	float S2 = ((P4.x-P2.x)*(P2.y-P3.y)-(P4.y-P2.y)*(P2.x-P3.x))*0.5f;
	Vector3 crossPoint = new Vector3(0,0,0);
	crossPoint.x = P1.x + (P3.x-P1.x)*(S1/(S1 + S2));
	crossPoint.y = P1.y + (P3.y-P1.y)*(S1/(S1 + S2));

	return crossPoint;
}