public static LVector2 GetIntersectPoint(LVector2 p0, LVector2 p1, LVector2 p2, LVector2 p3)
{
var diff = p2 - p0;
var d1 = p1 - p0;
var d2 = p3 - p2;
var demo = LMath.Cross2D(d1, d2); //det
if (LMath.Abs(demo) < LFloat.EPSILON) //parallel
{
return(p0);
}
var t1 = LMath.Cross2D(diff, d2) / demo; // Cross2D(diff,-d2)
return(p0 + (p1 - p0) * t1);
}
/// <summary>
///
/// </summary>
/// <param name="o">射线的起点</param>
/// <param name="d1">射线的终点</param>
/// <param name="p2">多边形的顶点</param>
/// <param name="p3">多边形相邻的顶点（和p2 组成线段）</param>
/// <returns>返回大于等于0时 说明相交</returns>
public static LFloat TestRaySegment(LVector2 o, LVector2 d1, LVector2 p2, LVector2 p3)
{
LVector2 diff = p2 - o;
LVector2 d2 = p3 - p2;
// 叉乘的结果如过为0 说明平行
LFloat dome = LMath.Cross2D(d1, d2);
if (LMath.Abs(dome) < LFloat.EPSILON)
{
return(LFloat.negOne);
}
LFloat t1 = LMath.Cross2D(d2, diff);
LFloat t2 = LMath.Cross2D(d1, diff);
if (t1 >= 0 && (t2 >= 0 && t2 <= 1))
{
return(t1);
}
return(LFloat.negOne);
}
public static LFloat TestSegmentSegment(LVector2 p0, LVector2 p1, LVector2 p2, LVector2 p3)
{
LVector2 diff = p2 - p0;
LVector2 d1 = p1 - p0;
LVector2 d2 = p3 - p2;
var demo = LMath.Cross2D(d1, d2);
if (LMath.Abs(demo) < LFloat.EPSILON) //parallel
{
return(LFloat.negOne);
}
var t1 = LMath.Cross2D(d2, diff) / demo; // Cross2D(diff,-d2)
var t2 = LMath.Cross2D(d1, diff) / demo; //Dot(v1,pd0) == cross(d0,d1)
if ((t1 >= 0 && t1 <= 1) && (t2 >= 0 && t2 <= 1))
{
return(t1); // return p0 + (p1-p0) * t1
}
return(LFloat.negOne);
}
