计算机图形学01—分形树（OpenGL）（C++语言）

本篇用来展示使用OpenGL做的分形树。编程语言使用的是C++语言。

程序运行结果如下所示：

在这里插入图片描述

在程序中还设置了场景漫游，可以使用键盘来控制前进、后退、向左转以及向右转。

程序代码：

由于程序较多，这里展示画分形树的重要函数代码，完整代码资源可见计算机图形学—分形树（OpenGL）

void LSystemRule1()
{
	//初始化
	//std::cout << "进入LSystemRule()" << endl;
	way = "FA[+X][-&X]-%XB";
	//std::cout << "进入LSystemRule()  定义了三条规则" << endl;
	len = 30.0f;//长度
	Alphaz = 40;
	Alphay = 60;
	n = 8;
	k = 0;
	stackpointer = 0;//栈顶指针
	for (int i = 0; i < 150; i++)
	{
		stack[i].point.x = 0.0;
		stack[i].point.y = 0.0;
		stack[i].point.z = 0.0;
		stack[i].directionz = NULL;
		stack[i].directiony = NULL;
	}
	temprule = way;
	for (int i = 1; i <= n; i++)
	{
		int curlen = temprule.length();
		int pos = 0, j = 0;
		while (j < curlen)
		{
			if (temprule[j] == 'X')//迭代，将其中的F替换成文法模型
			{
				rule += way;
				j++;
				pos = rule.length() - 1;
			}
			else//保留转角
			{
				rule += temprule[j];
				pos++;
				j++;
			}
		}
		temprule = rule;
		rule.clear();
	}
	rule = temprule;//迭代好之后的文法规则

}
void LSystemRule2()
{
	//初始化
	std::cout << "进入LSystemRule()" << endl;
	/*grassway[0] = "FFF[+&FF]F[-%%%%%&F]F";
	grassway[1] = "FFF[+%FF]F[-F&[+%F]]";
	grassway[2] = "FF-[&&--F+F+F]+[%+F+F-F]";
	grassway[3] = "FF[+F+F-[++F-F++F]]F[--F-F+[F-F++F]]";
	grassway[4] = "FF[&F&F%[F%F&&F]]F[%F%F&[F%F&&F]]";*/
	gr = "FF[+%%F+F-[%F-F++F]]F[%-F-F+[F-F++F]]";
	std::cout << "进入LSystemRule()  定义了三条规则" << endl;
	lenline = 0.1f;//长度
	Alpha = 35;
	num = 2;

	stackpointer1 = 0;
	for (int i = 0; i < 150; i++)
	{
		stack1[i].point.x = 0.0;
		stack1[i].point.y = 0.0;
		stack1[i].point.z = 0.0;
		stack1[i].directiony = NULL;
		stack1[i].directionz = NULL;
	}
	//rule = way[0];
	//rule1 = grassway[rand() % 5];
	rule1 = gr;
	for (int i = 1; i <= num; i++)
	{
		int curlen = temprule1.length();
		//cout << curlen << endl;
		int pos = 0, j = 0;
		while (j < curlen)
		{
			if (temprule1[j] == 'F')
			{
				//rule1 += grassway[rand() % 5];
				rule1 += gr;
				//rule = way[0];
				j++;
				pos = rule1.length() - 1;
			}
			else
			{
				rule1 += temprule1[j];
				pos++;
				j++;
			}
		}
		temprule1 = rule1;
		//rule1.empty();
		rule1.clear();
	}
	rule1 = temprule1;

	std::cout << "出LSystemRule()" << endl;
}

void drawGrass(CVector3D p,float R,float G,float B)
{
	Node  Nextnode, Curnode;
	Curnode.point.x = p.x;
	Curnode.point.y = p.y;
	Curnode.point.z = p.z;
	Curnode.directionz = -85;
	Curnode.directiony = 0;
	int length = rule1.length();
	//std::cout << "长度 = " << length << endl;
	int  i = 0;
	//cout << rule << endl;
	glRotatef(180, 1.0, 0.0, 0.0);
	glTranslatef(0.0, 30.0, 0.0);
	glPushMatrix();
	while (i < length)
	{

		//std::cout << "rule[i] = " << rule[i] << endl;
		switch (rule1[i])
		{
		case 'F':
			Nextnode.point.x = Curnode.point.x + lenline * cos(Curnode.directionz * PI / 180) * cos(Curnode.directiony * PI / 180);
			Nextnode.point.y = Curnode.point.y + lenline * sin(Curnode.directionz * PI / 180);
			Nextnode.point.z = Curnode.point.z - lenline * cos(Curnode.directionz * PI / 180) * sin(Curnode.directiony * PI / 180);
			Nextnode.directiony = Curnode.directiony;
			Nextnode.directionz = Curnode.directionz;
			/*std::cout << "Nextnode.point.x= " << Nextnode.point.x << endl;
				std::cout << "Nextnode.point.y= " << Nextnode.point.y << endl;
				std::cout << "Nextnode.point.z= " << Nextnode.point.z << endl;*/
			glBegin(GL_LINES);
			glColor3f(R,G,B);
			glVertex3f(Curnode.point.x, Curnode.point.y, Curnode.point.z);
			glVertex3f(Nextnode.point.x, Nextnode.point.y, Nextnode.point.z);
			glEnd();
			Curnode = Nextnode;
			break;
		case '[':
			stack1[stackpointer1] = Curnode;
			stackpointer1++;
			break;
		case ']':
			Curnode = stack1[stackpointer1 - 1];
			stackpointer1--;
			break;
		case '+':
			Curnode.directionz = Curnode.directionz + Alpha;
			break;
		case '-':
			Curnode.directionz = Curnode.directionz - Alpha;
			break;
		case '&':
			Curnode.directiony = Curnode.directiony + Alpha;
			break;
		case '%':
			Curnode.directiony = Curnode.directiony - Alpha;
			break;
		default:
			;
		}
		i++;
	}
	glPopMatrix();
	//std::cout << "完成！" << endl;
}