private bool TwoLineIsIntersect(float x0, float y0, float x1, float y1, float x2, float y2, float x3, float y3, ref float InterX,ref float InterY)
{
//兩條線段是否相交X0X1 AND X1X2
float x, y;
float Minx01 = Math.Min(x0, x1);
float Miny01 = Math.Min(y0, y1);
float Minx23 = Math.Min(x2, x3);
float Miny23 = Math.Min(y2, y3);
float Maxx01 = Math.Max(x0, x1);
float Maxy01 = Math.Max(y0, y1);
float Maxx23 = Math.Max(x2, x3);
float Maxy23 = Math.Max(y2, y3);
if(x1!=x0 && x2!=x3)
{
float k1 = (y1-y0)/(x1-x0);
float k2 = (y3-y2)/(x3-x2);
float Den = (y1-y0)*(x3-x2) - (y3-y2)*(x1-x0);
if(k1==k2)
{ //平行不相交
float d1 = abs(y0*(x1-x0)-x0*(y1-y0)-y2*(x3-x2)+x2*(y3-y2)); //距離公式d = abs(c1-c2) / sqrt(a*a+b*b)
if(d1==0)
{//直線重合
if((x2>Minx01 && x2<Maxy01 && y2>Miny01 && y2<Maxy01) || (x3>Minx01 && x3<Maxy01 && y3>Miny01 && y3<Maxy01)
|| (x0>Minx23 && x0<Maxy23 && y0>Miny23 && y0<Maxy23) || (x1>Minx23 && x1<Maxy23 && y1>Miny23 && y1<Maxy23))
{ //實際碰撞問題線段重合認為相交了
return true;
}
else
{
return false;
}
}
else
{
return false;
}
}
x = ((y2-y0)*(x1-x0)*(x3-x2)+(y1-y0)*(x3-x2)*x0-(y3-y2)*(x1-x0)*x2)/Den;
y = ((y1-y0)*(x-x0))/(x1-x0) + y0;
if(Minx01<=x && x<=Maxx01 && Miny01<=y && y<=Maxy01 && Minx23<=x && x<=Maxx23 && Miny23<=y && y<=Maxy23)
{
InterX = x;
InterY = y;
return true;
}
}
else if(x1==x0 && x2!=x3)
{
x = x0;
y = ((y3-y2)*(x0-x2))/(x3-x2) + y2;
if(Minx01<=x && x<=Maxx01 && Miny01<=y && y<=Maxy01 && Minx23<=x && x<=Maxx23 && Miny23<=y && y<=Maxy23)
{
InterX = x;
InterY = y;
return true;
}
}
else if(x1!=x0 && x2==x3)
{
x = x2;
y = ((y1-y0)*(x2-x0))/(x1-x0) + y0;
if(Minx01<=x && x<=Maxx01 && Miny01<=y && y<=Maxy01 && Minx23<=x && x<=Maxx23 && Miny23<=y && y<=Maxy23)
{
InterX = x;
InterY = y;
return true;
}
}
return false;
}