Sierpinski.cpp

#include <glut.h>
#include <stdlib.h>
#include <vector>
using namespace std;

class Point2d {
public:
	GLfloat x = 0.0f;
	GLfloat y = 0.0f;
	Point2d(const GLfloat &a, const GLfloat &b): x(a), y(b){}
	Point2d(){}
};

Point2d triVer[3];  // 初始三角形顶点

// 计算两点连线的中点
Point2d halfScale(const Point2d &a, const Point2d &b) {
	Point2d res;
	res.x = (a.x + b.x) / 2.0;
	res.y = (a.y + b.y) / 2.0;
	return res;
}

void SierpinskiDisp() {

	// 设置初始三角形顶点
	triVer[0] = Point2d(-0.8f, -0.8f);
	triVer[1] = Point2d(0.0f, 0.8f);
	triVer[2] = Point2d(0.8f, -0.8f);

	vector<Point2d> points(5000);

	// 取三角形一条中位线的中点做为初始三角形内的点
	Point2d u, v, p;
	u = halfScale(triVer[0], triVer[1]);
	v = halfScale(triVer[0], triVer[2]);
	p = halfScale(u, v);
	points[0].x = p.x;
	points[0].y = p.y;

	for (int i = 1; i < 5000; i++) {
		int j = rand() % 3;
		p = halfScale(points[i - 1], triVer[j]);
		points[i] = p;
	}
	glClearColor(0.5, 0.5, 0.5, 1.0);
	glClear(GL_COLOR_BUFFER_BIT);

	// 画三角形顶点
	glColor3f(1.0f, 0.0f, 0.0f);
	glPointSize(6.0f);
	glBegin(GL_POINTS);
	for (int i = 0; i < 3; i++) {
		glVertex2f(triVer[i].x, triVer[i].y);
	}
	glEnd();

	// 画随机生成的5000个点
	glColor3f(1.0f, 1.0f, 0.0f);
	glPointSize(3.0f);
	glBegin(GL_POINTS);
	for (int i = 0; i < 5000; i++) {
		glVertex2f(points[i].x, points[i].y);
	}
	glEnd();
	glFlush();
}

int main(int argc, char *argv[]) {
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
	glutInitWindowPosition(100, 100);
	glutInitWindowSize(600, 600);
	glutCreateWindow("Sierpinski镂垫");
	glutDisplayFunc(&SierpinskiDisp);
	glutMainLoop();
}