给定三角形ABC和一点P(x,y,z),判断点P是否在ABC内,给出思路并手写代码
作者:互联网
根据面积法,如果P在三角形ABC内,那么三角形ABP的面积+三角形BCP的面积+三角形ACP的面积应该等于三角形ABC的面积。算法如下:
#include<iostream> #include<math.h> using namespace std; #define ABS_FLOAT_0 0.0001; struct point_float { float x; float y; }; float GetTriangleSquar(const point_float pt0, const point_float pt1, const point_float pt2) { point_float AB, BC; AB.x = pt1.x - pt0.x; AB.y = pt1.y - pt0.y; BC.x = pt2.x - pt1.x; BC.y = pt2.y - pt1.y; return fabs((AB.x*BC.y - AB.y*BC.x)) / 2.0f; } bool IsInTriangle(const point_float A, const point_float B, const point_float C, const point_float D) { float SABC, SADB, SBDC, SADC; SABC = GetTriangleSquar(A, B, C); SADB = GetTriangleSquar(A, D, B); SBDC = GetTriangleSquar(B, D, C); SADC = GetTriangleSquar(A, D, C); float SumSuqar = SADB + SBDC + SADC; if ((-0.0001 < (SABC - SumSuqar)) && ((SABC - SumSuqar) < 0.0001)) { return true; } else { return false; } } int main() { point_float pt0; pt0.x = 0; pt0.y = 0; point_float pt1; pt1.x = 0; pt1.y = 3; point_float pt2; pt2.x = 4; pt2.y = 0; point_float pt3; pt3.x = 4; pt3.y = 0; int a, b; a=GetTriangleSquar(pt0, pt1, pt2); b=IsInTriangle(pt0, pt1, pt2, pt3); cout << a << " " << b << endl; system("pause"); return 0; }
标签:ABC,const,point,float,给定,手写,pt2,pt1,pt0 来源: https://www.cnblogs.com/277223178dudu/p/11063293.html