三角形插值

// 计算权重 CalculateWeight
BOOL CalcWeight(const osg::Vec3d& p0, const osg::Vec3d& p1, const osg::Vec3d& p2, const osg::Vec3d& k, double& a, double& b, double& c)
{
	double Area = (-p1[1] * p2[0] + p0[1] * (-p1[0] + p2[0]) + p0[0] * (p1[1] - p2[1]) + p1[0] * p2[1]);

	//if (abs(Area) < 1.0e-3)
	//	return FALSE;

	b = (p0[1] * p2[0] - p0[0] * p2[1] + (p2[1] - p0[1]) * k[0] + (p0[0] - p2[0]) * k[1]) / Area;
	c = (p0[0] * p1[1] - p0[1] * p1[0] + (p0[1] - p1[1]) * k[0] + (p1[0] - p0[0]) * k[1]) / Area;
	a = 1 - c - b;
	if (a >= 0 && b >= 0 && c >= 0)
	{
		return TRUE;
	}
	else
	{
		return FALSE;  //顶点在三角形外
	}

	return TRUE;
}