HDU 4741 Save Labman No.004(计算几何)

题目链接

抄的模版。。。mark一下。

 #include <iostream>
 #include <cstring>
 #include <cstdio>
 #include <cstdlib>
 #include <algorithm>
 #include <cmath>
 using namespace std;
 #define eps 1e-10
 #define zero(x) (((x) > 0?(x):(-x)) < eps)
 struct point3
 {
     double x,y,z;
 };
 struct line3
 {
     point3 a,b;
 };
 struct plane3
 {
     point3 a,b,c;
 };
 point3 xmult(point3 u,point3 v)
 {
     point3 ret;
     ret.x = u.y*v.z - v.y*u.z;
     ret.y = u.z*v.x - u.x*v.z;
     ret.z = u.x*v.y - u.y*v.x;
     return ret;
 }
 point3 subt(point3 u,point3 v)
 {
     point3 ret;
     ret.x = u.x - v.x;
     ret.y = u.y - v.y;
     ret.z = u.z - v.z;
     return ret;
 }
 double dmult(point3 u,point3 v)
 {
     return u.x*v.x + u.y*v.y + u.z*v.z;
 }
 double vlen(point3 p)
 {
     return sqrt(p.x*p.x + p.y*p.y + p.z*p.z);
 }
 double linetoline(line3 u,line3 v)
 {
     point3 n = xmult(subt(u.a,u.b),subt(v.a,v.b));
     return fabs(dmult(subt(u.a,v.a),n))/vlen(n);
 }
 point3 intersection(line3 u,line3 v)
 {
     point3 ret = u.a;
     double t = ((u.a.x-v.a.x)*(v.a.y-v.b.y)-(u.a.y-v.a.y)*(v.a.x-v.b.x))
     /((u.a.x-u.b.x)*(v.a.y-v.b.y)-(u.a.y-u.b.y)*(v.a.x-v.b.x));
     ret.x += (u.b.x-u.a.x)*t;
     ret.y += (u.b.y-u.a.y)*t;
     ret.z += (u.b.z-u.a.z)*t;
     return ret;
 }
 
 //求面线交点
 point3 pvec(plane3 s)
 {
     return xmult(subt(s.a,s.b),subt(s.b,s.c));
 }
 point3 intersection(line3 l,plane3 s)
 {
     point3 ret = pvec(s);
     double t = (ret.x*(s.a.x-l.a.x)+ret.y*(s.a.y-l.a.y)+ret.z*(s.a.z-l.a.z))/
     (ret.x*(l.b.x-l.a.x)+ret.y*(l.b.y-l.a.y)+ret.z*(l.b.z-l.a.z));
     ret.x = l.a.x + (l.b.x-l.a.x)*t;
     ret.y = l.a.y + (l.b.y-l.a.y)*t;
     ret.z = l.a.z + (l.b.z-l.a.z)*t;
     return ret;
 }
 int dots_oneplane(point3 a,point3 b,point3 c,point3 d)
 {
     plane3 temp;
     temp.a = a;
     temp.b = b;
     temp.c = c;
     return zero(dmult(pvec(temp),subt(d,a)));
 }
 int main()
 {
     int t;
     double ans;
     scanf("%d",&t);
     line3 u,v,te,ni;
     point3 st,u1,v1,ans1,ans2;
     plane3 ds;
     while(t--)
     {
         scanf("%lf%lf%lf",&u.a.x,&u.a.y,&u.a.z);
         scanf("%lf%lf%lf",&u.b.x,&u.b.y,&u.b.z);
         scanf("%lf%lf%lf",&v.a.x,&v.a.y,&v.a.z);
         scanf("%lf%lf%lf",&v.b.x,&v.b.y,&v.b.z);
         if(dots_oneplane(u.a,u.b,v.a,v.b))
         {
             printf("0.000000\n");
             ans1 = ans2 = intersection(u,v);
             printf("%.6f %.6f %.6f %.6f %.6f %.6f\n",ans2.x,ans2.y,ans2.z,ans1.x,ans1.y,ans1.z);
             continue;
         }
         ans = linetoline(u,v);
         printf("%.6lf\n",ans);
         st = xmult(subt(u.a,u.b),subt(v.a,v.b));
         ds.a = v.a;
         ds.b = v.b;
         ds.c.x = v.a.x + (u.a.x-u.b.x);
         ds.c.y = v.a.y + (u.a.y-u.b.y);
         ds.c.z = v.a.z + (u.a.z-u.b.z);
 
         te.a = u.a;
         te.b.x = u.a.x + st.x;
         te.b.y = u.a.y + st.y;
         te.b.z = u.a.z + st.z;
         u1 = intersection(te,ds);
         v1.x = u1.x + (u.a.x-u.b.x);
         v1.y = u1.y + (u.a.y-u.b.y);
         v1.z = u1.z + (u.a.z-u.b.z);
         ni.a = u1;
         ni.b = v1;
         ans1 = intersection(ni,v);
         ans2.x = ans1.x + (u.a.x - u1.x);
         ans2.y = ans1.y + (u.a.y - u1.y);
         ans2.z = ans1.z + (u.a.z - u1.z);
         printf("%.6f %.6f %.6f %.6f %.6f %.6f\n",ans2.x,ans2.y,ans2.z,ans1.x,ans1.y,ans1.z);
     }
     return ;
 }