这是一个绘制星星的类,作为 Bjarne Stroustrup的C ++编程:原理与实践的第13章练习19的一部分。
类
Star
使用五角形,六角形,七角形和八角形作为基础以及具有多个星形的属性(旋转对称)顶点(10,12,14,18等)有,以绘制n-gram 1 :
Chapter13Exercise19.cpp
#include "GUI.h"
#include "Simple_window.h"
#include <iostream>
#include "Chapter13Exercise19.h"
int main(){
// window parameters
int winWidth = 800;
int winHeight = 600;
Point centerPoint((x_max() - winWidth) / 2, (y_max() - winHeight) / 2);
Simple_window* siw = new Simple_window(centerPoint, winWidth,
winHeight, "Chapter 13 Exercise 19");
try{
Point center(siw->x_max()/2, siw->y_max()/2);
int radius = 150;
// Currenly: sides > 5, sides =! 13, 17, 19 and multiples
int sides = 16;
Graph_lib::Star st(center, radius, sides);
siw->attach(st);
siw->wait_for_button();
}catch(exception& e){
cerr << e.what() << endl;
getchar();
}catch(const std::invalid_argument& e){
cerr << e.what() << endl;
getchar();
}catch(...){
cerr <<"Defaul exception!"<< endl;
getchar();
}
}
Chapter13Exercise19.h
#ifndef _Chapter13Exercise19_H_
#define _Chapter13Exercise19_H_
#define PI 3.14159265359
namespace Graph_lib{
class Star: public Lines{
public:
Star(Point c, int r, int n);
private:
int vertexNumber;
Point center;
int radius;
vector<Point>starCoordinates;
// parameters kept as function recursive
void rotateCoordinate(Point& axisOfRotation, Point& initial,
double angRads, int numberOfRotations);
void generatePoly();
void makeStar();
};
#include "Chapter13Exercise19Def.cpp"
} // end of namespace Graph_lib
#endif
Chapter13Exercise19Def.cpp
// Class Members implementation
Star::Star(Point c, int r, int n)
: vertexNumber(n), center(c), radius(r)
{
if(n < 5) throw std::invalid_argument("Not enough verteces!");
generatePoly();
makeStar();
}
void Star::rotateCoordinate(Point& axisOfRotation, Point& initial,
double angRads, int numberOfRotations){
if(numberOfRotations <= 0) return;
else{
double x = cos(angRads) * (initial.x - axisOfRotation.x)
- sin(angRads) * (initial.y - axisOfRotation.y) + axisOfRotation.x;
double y = sin(angRads) * (initial.x - axisOfRotation.x)
+ cos(angRads) * (initial.y - axisOfRotation.y) + axisOfRotation.y;
starCoordinates.push_back(Point(x, y));
rotateCoordinate(axisOfRotation, Point(x,y), angRads, --numberOfRotations);
}
}
void Star::generatePoly(){
double angRads = (PI / 180.) * (360. / vertexNumber);
Point initial(center.x, center.y - radius);
rotateCoordinate(center, initial, angRads, vertexNumber);
}
void Star::makeStar(){
// every if statement covers Star with n and multiples of n vertexes
// the inner for loops execute one iteration for the fundamental stars
// and n iterations for the multiples (rotational symmetry)
if (vertexNumber % 5 == 0){
for (size_t it = 0; it < starCoordinates.size() / 5; ++it){
Lines::add(starCoordinates[it+3], starCoordinates[it]);
Lines::add(starCoordinates[it], starCoordinates[it+2]);
Lines::add(starCoordinates[it+2], starCoordinates[it+4]);
Lines::add(starCoordinates[it+4], starCoordinates[it+1]);
Lines::add(starCoordinates[it+1], starCoordinates[it+3]);
}
}else if (vertexNumber % 3 == 0){
for (size_t it = 0; it < starCoordinates.size() / 3; ++it){
Lines::add(starCoordinates[it], starCoordinates[it+2]);
Lines::add(starCoordinates[it+2], starCoordinates[it+4]);
Lines::add(starCoordinates[it+4], starCoordinates[it]);
}
}else if (vertexNumber % 7 == 0){
for (size_t it = 0; it < starCoordinates.size() / 7; ++it){
Lines::add(starCoordinates[it], starCoordinates[it+3]);
Lines::add(starCoordinates[it+3], starCoordinates[it+6]);
Lines::add(starCoordinates[it+6], starCoordinates[it+2]);
Lines::add(starCoordinates[it+2], starCoordinates[it+5]);
Lines::add(starCoordinates[it+5], starCoordinates[it+1]);
Lines::add(starCoordinates[it+1], starCoordinates[it+4]);
Lines::add(starCoordinates[it+4], starCoordinates[it]);
}
}else if (vertexNumber % 8 == 0){
for (size_t it = 0; it < starCoordinates.size() / 8; ++it){
Lines::add(starCoordinates[it], starCoordinates[it+5]);
Lines::add(starCoordinates[it+5], starCoordinates[it+2]);
Lines::add(starCoordinates[it+2], starCoordinates[it+7]);
Lines::add(starCoordinates[it+7], starCoordinates[it+4]);
Lines::add(starCoordinates[it+4], starCoordinates[it+1]);
Lines::add(starCoordinates[it+1], starCoordinates[it+6]);
Lines::add(starCoordinates[it+6], starCoordinates[it+3]);
Lines::add(starCoordinates[it+3], starCoordinates[it]);
}
} else throw std::invalid_argument("Star vertexes'number not supported!");
}
虽然所有的基本多边形(5,6,7,8个顶点)看起来都应该如此,但在带有顶点的多边形的情况下:10,12,14等,我得到了这些部分完成的图。
我知道问题来自makeStar()
中的函数Chapter13Exercise19Def.cpp
,但我无法弄清楚问题是什么。
答案 0 :(得分:2)
我无法真正使用您的代码,因为它依赖于您正在使用的可视化库,但我知道问题是什么,并且我非常有信心我知道解决方案。
rotateCoordinate
递归函数生成一个点向量,沿着polygram的边界圆均匀分布,按顺时针方向排序。
然后当你构造定义(绘制...)polygram的线时,你使用这些点,但你不是用来纠正索引。例如,假设你有一个polygram {16/2}(2个hexagrams),你有0-15个索引点,但生成这些行的for
循环最多会达到索引8({ {1}},索引it = 1
),这显然是错误的。
你应该做的是将你的常数(你添加到[it + 7]
的数字)乘以多边形中的多边形数,所以在{16/2}的情况下,这将是2。 / p>
试试这段代码:
it