115 lines
3.7 KiB
C++
115 lines
3.7 KiB
C++
#include<stdio.h>
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#include<string.h>
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#include<stdlib.h>
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#include<math.h>
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#include<algorithm>
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const int maxn = 111111;
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const int maxisn = 21;
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const double eps = 1e-8;
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const double pi = acos(-1.0);
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int dcmp(double x)
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{
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if(x > eps) return 1;
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return x < -eps ? -1 : 0;
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}
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struct Point
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{
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double x, y;
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Point(){x = y = 0;}
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Point(double a, double b)
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{x = a, y = b;}
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inline Point operator-(const Point &b)const
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{return Point(x - b.x, y - b.y);}
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inline Point operator+(const Point &b)const
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{return Point(x + b.x, y + b.y);}
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inline Point operator*(const double &b)const
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{return Point(x * b, y * b);}
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inline double dot(const Point &b)const
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{return x * b.x + y * b.y;}
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inline double cross(const Point &b, const Point &c)const
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{return (b.x - x) * (c.y - y) - (c.x - x) * (b.y - y);}
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inline double Dis(const Point &b)const
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{return sqrt((*this - b).dot(*this - b));}
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inline bool InLine(const Point &b, const Point &c)const
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{return !dcmp(cross(b, c));}
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inline bool OnSeg(const Point &b, const Point &c)const
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{return InLine(b, c) && (*this - c).dot(*this - b) < eps;}
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};
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inline double min(double a, double b)
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{return a < b ? a : b;}
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inline double max(double a, double b)
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{return a > b ? a : b;}
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inline double Sqr(double x)
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{return x * x;}
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inline double Sqr(const Point &p)
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{return p.dot(p);}
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Point LineCross(const Point &a, const Point &b, const Point &c, const Point &d)
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{
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double u = a.cross(b, c), v = b.cross(a, d);
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return Point((c.x * v + d.x * u) / (u + v), (c.y * v + d.y * u) / (u + v));
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}
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double LineCrossCircle(const Point &a, const Point &b, const Point &r,
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double R, Point &p1, Point &p2)
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{
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Point fp = LineCross(r, Point(r.x + a.y - b.y, r.y + b.x - a.x), a, b);
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double rtol = r.Dis(fp);
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double rtos = fp.OnSeg(a, b) ? rtol : min(r.Dis(a), r.Dis(b));
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double atob = a.Dis(b);
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double fptoe = sqrt(R * R - rtol * rtol) / atob;
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if(rtos > R - eps) return rtos;
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p1 = fp + (a - b) * fptoe;
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p2 = fp + (b - a) * fptoe;
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return rtos;
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}
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double SectorArea(const Point &r, const Point &a, const Point &b, double R)
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{
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double A2 = Sqr(r - a), B2 = Sqr(r - b), C2 = Sqr(a - b);
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return R * R * acos((A2 + B2 - C2) * 0.5 / sqrt(A2) / sqrt(B2)) * 0.5;
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}
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double TACIA(const Point &r, const Point &a, const Point &b, double R)
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{
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double adis = r.Dis(a), bdis = r.Dis(b);
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if(adis < R + eps && bdis < R + eps) return r.cross(a, b) * 0.5;
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Point ta, tb;
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if(r.InLine(a, b)) return 0.0;
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double rtos = LineCrossCircle(a, b, r, R, ta, tb);
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if(rtos > R - eps) return SectorArea(r, a, b, R);
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if(adis < R + eps) return r.cross(a, tb) * 0.5 + SectorArea(r, tb, b, R);
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if(bdis < R + eps) return r.cross(ta, b) * 0.5 + SectorArea(r, a, ta, R);
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return r.cross(ta, tb) * 0.5 +
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SectorArea(r, a, ta, R) + SectorArea(r, tb, b, R);
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}
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double SPICA(int n, Point r, double R)
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{
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int i;
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Point ori, p[2];
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scanf("%lf%lf", &ori.x, &ori.y);
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p[0] = ori;
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double res = 0, if_clock_t;
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for(i = 1; i <= n; ++ i)
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{
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if(i == n) p[i & 1] = ori;
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else scanf("%lf%lf", &p[i & 1].x, &p[i & 1].y);
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if_clock_t = dcmp(r.cross(p[~i & 1], p[i & 1]));
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if(if_clock_t < 0) res -= TACIA(r, p[i & 1], p[~i & 1], R);
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else res += TACIA(r, p[~i & 1], p[i & 1], R);
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}
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return fabs(res);
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}
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Point boom;
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int n;
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double R;
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int main()
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{
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double sx, sy, h, vx, vy;
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while(scanf("%lf%lf%lf", &sx, &sy, &h) != EOF)
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{
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scanf("%lf%lf%lf", &vx, &vy, &R);
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h = sqrt(2 * h / 10);
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boom = Point(h * vx + sx, h * vy + sy);
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scanf("%d", &n);
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printf("%.2f\n", SPICA(n, boom, R));
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}
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return 0;
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}
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