C++扫描线算法 C++实现基于EASYX库扫描线算法

#include<graphics.h>
//#include<conio.h>
#include<iostream>
using namespace std;
//-----------------------------草图形-----------------------------//
void Grass(double x, double y, double hight, double width)
{
 setlinecolor(GREEN);
 line(x, y, x - hight / 2, y - width);
 line(x, y, x, y - width);
 line(x, y, x + hight / 2, y - width);
}
//-----------------------------林图形-----------------------------//
void Tree(double x, double y, double hight, double width)
{
 setlinecolor(GREEN);
 line(x, y, x - hight / 2, y - width);
 line(x, y, x + hight / 2, y - width);
 line(x, y - width, x, y + width);
}
//------------------求解方程的k,b值---------------------//
void function_line(double x1, double y1, double x2, double y2, double &k, double &b)
{
 if (x2 - x1 == 0) {
 k = -9999;
 b = x1;
 return;
 }
 k = (y2 - y1) / (x2 - x1);
 b = y1 - k * x1;
}
//------------------返回直线的y----------------------//
double solve_y(double k, double b, double x)
{
 return k * x + b;
}
//------------------返回直线的x----------------------//
double solve_x(double k, double b, double y)
{
 if (k == -9999)
 return b;
 return (y - b) / k;
}
//-------------------找出扫描线与边界相交的点，并储存在suitable_x[]中，把相交的点数储存在n中--------------//
//x[]-----------顶点x坐标
//y[]-----------顶点y坐标
//N-------------顶点的个数
//now_y---------当前的扫描线y
//suitable_x[]--扫描线与边界相交的点的x坐标
//n-------------相交的点数
void Suitable_x(double x[], double y[],int N, double now_y, double suitable_x[], int &n) 
{
 n = 0;
 int t = 0;
 double k, b;
 for (int i = 0; i < N; i++)
 {
 if (i == N - 1)
 {
 if (y[i] < now_y&& now_y <= y[0] || y[0] < now_y&& now_y <= y[i])//判断直线是否过最后一条直线
 {
 function_line(x[0], y[0], x[i], y[i], k, b);
 suitable_x[t++] = solve_x(k, b, now_y);
 }
 }
 else
 {
 if (y[i] < now_y&& now_y <= y[i + 1] || y[i + 1] < now_y&& now_y <= y[i]) //判断扫描线过哪条直线的范围
 {
 function_line(x[i], y[i], x[i + 1], y[i + 1], k, b);
 suitable_x[t++] = solve_x(k, b, now_y);//把交点的x储存在suitable_x[]中
 }
 }
 }
 n = t;
}
void sort_min_to_max(double suitable_x[],int n) //排序----从小到大排序
{
 double temp;
 for (int i = 0; i < n - 1; i++)
 {
 for (int j = i + 1; j < n; j++) {
 if (suitable_x[i] > suitable_x[j]) {
 double temp = suitable_x[i];
 suitable_x[i] = suitable_x[j];
 suitable_x[j] = temp;
 }
 }
 }
}
double find_max(double elem[],int N) //输出最大的元素值
{
 double max = elem[0];
 for (int i = 0; i < N; i++)
 {
 if (elem[i] > max)
 {
 max = elem[i];
 }
 }
 return max;
}
double find_min(double elem[],int N) //输出最小的元素值
{
 double min = elem[0];
 for (int i = 0; i < N; i++)
 {
 if (elem[i] < min)
 {
 min = elem[i];
 }
 }
 return min;
}
int main()
{
 cout << "-----------------------------------------地物填充绘制算法--------------------------------------------\n\n";
 cout << "           创建人：李景勃\n";
 cout << "            时间：2018年10月24日\n";
 cout << "  10月24日是全部程序员值得开心的节日，也是自己重要的日子，23号完成，祝福全部程序员们！！！ \n\n\n";

 int N,ch;
 char color;
 double x[50],y[50];
 cout << "输入填充的多边形的顶点数：";
 cin >> N;
 cout << "依次输入地物的顶点坐标：";
 for (int i = 0; i < N; i++)
 {
 cout << "输入第" << i+1 << "个顶点的坐标:" << endl;
 cout << "x,y:";
 scanf_s("%lf,%lf",&x[i],&y[i]);
 /*cout << "x = "; cin >> x[i];
 cout << "y = "; cin >> y[i];*/
 }
 cout << "选择您填充的地物： 整个区域单颜色充填---请按0；草地---请按 1；林地---请按 2 ； "; cin >> ch;
 if (ch == 0)
 {
 cout << "请选择颜色：BLACK 黑，DARKGRAY 深灰绿色 BLUE 蓝　LIGHTBLUE 亮蓝：GREEN 绿 CYAN 青 RED 红 MAGENTA 紫 BROWN 棕 YELLOW 黄 LIGHTGRAY 浅灰---注意是大写的英文\n ";
 cout << "如果想让颜色变亮请在颜色的前面加上LIGHT \n";
 cout << "请输入颜色：";
 cin >> color;
 }


 initgraph(find_max(x, N)+100, find_max(y, N)+100);
 //int N = 9;
 //double x[50] = { 200,100,150,170,400,350,300,250,270 };
 //double y[50] = { 200,300,400,250,350,300,250,100,270 };
 double new_y[50] = { 0 };
 int n = 0;
 double suitable_x[10];
 //草的参数
 int hight = 12,
 width = 6;
 int space = 4; //草之间的间隔


 setbkcolor(WHITE); //设置背景色
 cleardevice(); //用背景色填充屏幕
 setlinecolor(BLACK); //多边形的线条颜色
 for (int i = 0; i < N; i++) //逆时针顶点相连构成闭合多边形
 {
 if (i == N - 1)
 {
 line(x[i], y[i], x[0], y[0]);
 }
 else
 {
 line(x[i], y[i], x[i + 1], y[i + 1]);
 }
 }

 double min_y = find_min(y,N),
 max_y = find_max(y,N);
 switch (ch)
 {
 case 0:
 //-------------------------像素填充面积-------------------------//
 for (int now_y = min_y; now_y <= max_y; now_y++)
 {
 Suitable_x(x, y, N, now_y, suitable_x, n);
 sort_min_to_max(suitable_x, n); //从小到大排序
 for (int i = 0; i < n; i += 2)
 {
 for (int now_x = suitable_x[i]; now_x < suitable_x[i + 1]; now_x++)//确定在扫描线上，要填充的范围
 {
 putpixel(now_x, now_y, color);
 }
 }
 }
 break;
 case 1:
 //-------------------------草填充-------------------------//
 for (int now_y = min_y + width + space; now_y <= max_y; now_y += width + space)
 {
 Suitable_x(x, y, N, now_y, suitable_x, n);
 sort_min_to_max(suitable_x, n); //从小到大排序
 for (int i = 0; i < n; i += 2)
 {
 for (int now_x = suitable_x[i] + hight / 2 + space + space; now_x < suitable_x[i + 1] - hight / 2; now_x += hight + space)//确定在扫描线上，要填充的范围
 {
 Grass(now_x, now_y, hight, width);
 Sleep(60);
 }
 }
 }
 break;
 case 2:
 //-------------------------树填充-------------------------//
 for (int now_y = min_y + width + space; now_y <= max_y; now_y += 2 * width + space)
 {
 Suitable_x(x, y, N, now_y, suitable_x, n);
 sort_min_to_max(suitable_x, n); //从小到大排序
 for (int i = 0; i < n; i += 2)
 {
 double longth = suitable_x[i + 1] - suitable_x[i]-space;
 int num = longth / (hight+space);
 //double space_tmp = longth - num * (hight + space);
 //double space_ = space + space / num;
 for (int now_x = suitable_x[i] + hight / 2 +space+space; now_x < suitable_x[i + 1] - hight / 2&&num--; now_x += hight + space)//确定在扫描线上，要填充的范围
 {
 Tree(now_x, now_y, hight, width);
 Sleep(60);
 }
 }
 }
 break;
 default:
 cout << "填充失败！！！" << endl;
 break;
 }
 //closegraph();//关闭画框
 system("pause");
 return 0;
}