snowflake.h

来自「这是清华出的这本经典的数据结构第三版上的随书例子。希望对大家有用。」· C头文件 代码 · 共 79 行

//************************  snowflake.h  ***************************
//                      Visual C++ program

#include <cmath>

double PI = 3.14159;

class vonKoch {
public:
    vonKoch(int,int,CDC*);
    void snowflake();
private:
    double side, angle;
    int level;
    CPoint currPt, pt;
    CDC *pen;
    void right(double x) {
        angle += x;
    }
    void left (double x) {
        angle -= x;
    }
    void drawFourLines(double side, int level);
};

vonKoch::vonKoch(int s, int lvl, CDC *pDC) {
    pen = pDC;
    currPt.x = 200;
    currPt.y = 100;
    pen->MoveTo(currPt);
    angle = 0.0;
    side = s;
    level = lvl;
}

void vonKoch::drawFourLines(double side, int level) { 
    // arguments to sin() and cos() are angles
    // specified in radians, i.e., the coefficient
    // PI/180 is necessary;
    if (level == 0) {                              // 
	   pt.x = int(cos(angle*PI/180)*side) + currPt.x; 
         pt.y = int(sin(angle*PI/180)*side) + currPt.y;
         pen->LineTo(pt);
         currPt.x = pt.x;
         currPt.y = pt.y;
    }
    else {                                        
         drawFourLines(side/3,level-1);
         left (60);
         drawFourLines(side/3,level-1);
         right(120);
         drawFourLines(side/3,level-1);
         left (60);
         drawFourLines(side/3,level-1);
    }
}

void vonKoch::snowflake() {
    for (int i = 1; i <= 3; i++) {
        drawFourLines(side,level);
            right(120);
    }
}

// The function OnDraw() is generated by Visual C++ when creating
// a snowflake project of type MFC AppWizard (exe), Single Document;
 
#include "a:snowflake.h"

void CSnowflakeView::OnDraw(CDC* pDC)
{
    CSnowflakeDoc* pDoc = GetDocument();
    ASSERT_VALID(pDoc);

    // TODO: add draw code for native data here

    vonKoch(200,4,pDC).snowflake();
}