综述

C+±计算三角形面片的法线代码；随手记下来，免得找不到

库

依然是CGAL 11

代码

Point calTriNormal( Point ver1, Point ver2, Point ver3 )

{

double temp1[3], temp2[3],normal[3];

double length = 0.0;

temp1[0] = ver1[0] - ver2[0];

temp1[1] = ver1[1] - ver2[1];

temp1[2] = ver1[2] -ver2[2];

temp2[0] = ver2[0] - ver3[0];

temp2[1] = ver2[1] - ver3[1];

temp2[2] = ver2[2] - ver3[2];

//计算法线

normal[0] =temp1[1]* temp2[2] - temp1[2]* temp2[1] ;

normal[1] = -(temp1[0]* temp2[2] - temp1[2]* temp2[0]) ;

normal[2] =temp1[0]* temp2[1] - temp1[1] * temp2[0] ;

//法线单位化

length = sqrt(normal[0] * normal[0] + normal[1]* normal[1]+ normal[2] * normal[2]);

if(length == 0.0f){length = 1.0f;}

normal[0]/= length ;
normal[1]/= length ;
normal[2]/= length ;
Point e_normal(normal[0],normal[1],normal[2]);
return e_normal;

}

使用

int main(int argc, char* argv[])
{


    Point a(1,0,0);
    Point b(0,1,0);
    Point c(0,0,1);
    cout << calTriNormal(a,b,c) << endl;
    return 0;
    }