1.原理
S=S1+S2+S3
S=三角片面积
Si判断点与三角片其中一条边组成的三角形
2.代码
#include <iostream>
#include <cmath>
using namespace std;
double CrossArea(double x1, double y1, double x2, double y2, double x3, double y3)
{
double ax=x2-x1,ay=y2-y1,bx=x2-x3,by=y2-y3;
return fabs(ax*by-ay*bx)/2;
}
bool judgePtInTriangle(double x1, double y1, double x2, double y2, double x3, double y3, double ptx, double pty)
{
double S = CrossArea(x1, y1, x2, y2, x3, y3);
double S1 = ......
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