平面多边形区域的扫描线填充算法

#include <iostream.h>#include <GL/glut.h>//#include<Windows.h>#include <math.h>#include <stdlib.h>//#pragma comment(lib, "Kernel32.lib")#define ROUND(a) ((int)(a+0.5))#define M 8 //定义多边形的顶点数+1#define maxx 600#define maxy 400int max,min;GLsizei winWidth = 600, winHeight = 400;float myabs(float aa){return aa>0 ? aa:aa*(-1);}struct active_edge_table{ //定义新边表的链表结点数据float x;float m;int ymin;struct active_edge_table *next;};struct active_edge_table *NET[maxy]; //定义新边表的Y桶指针数组struct active_edge_table *insert_node(struct active_edge_table *head, struct active_edge_table *stud);//活化边表插入结点操作struct active_edge_table * del_node(struct active_edge_table * head,int ys); //活化边表删除结点int y_min(int a[]); //取数组的最小值int y_max(int a[]); //取数组的最大值void polyNet(int px[M],int py[M]); //创建新边表的Y桶指针数组函数int y_min(int a[]){int j,min;min=a[0];for(j=1;j<M-1;j++)if(a[j]<min)min=a[j];return(min);}int y_max(int a[]){int j,max=a[0];for(j=1;j<M-1;j++)if(a[j]>max)max=a[j];return(max);}//创建新边表的Y桶指针数组函数void polyNet(int px[],int py[]){//请同学们完成创建新边表的Y桶指针数组函数；int ymin,ymax; ymin=y_min(py);ymax=y_max(py);int j=0,i=0,m=0; for(int y=ymax;y>=ymin;y--){for(j=0;j<M-1;j++)if(py[j]==y) { if(j==0){if(py[j+1]<py[j]&&py[M-2]<py[j]){ struct active_edge_table aa;struct active_edge_table bb;aa.m=float(px[j+1]-px[j])/(py[j+1]-py[j]);aa.m=myabs(aa.m);if(px[j+1]>px[j])aa.m=myabs(aa.m);elseaa.m=aa.m*(-1);aa.x=px[j]+aa.m;aa.ymin=py[j+1];bb.m=float(px[M-2]-px[j])/(py[M-2]-py[j]);bb.m=myabs(bb.m);if(px[M-2]>px[j]) bb.m=myabs(bb.m);elsebb.m=bb.m*(-1);bb.x=px[j]+bb.m;bb.ymin=py[M-2];bb.next=NULL;struct active_edge_table *p;if(NET[y-1]==NULL){NET[y-1]=new struct active_edge_table;NET[y-1]->m=aa.m;NET[y-1]->x=aa.x;NET[y-1]->ymin=aa.ymin;NET[y-1]->next=new struct active_edge_table;NET[y-1]->next->m=bb.m;NET[y-1]->next->ymin=bb.ymin;NET[y-1]->next->x=bb.x;NET[y-1]->next->next=bb.next;}else{p=NET[y-1];while(p->next!=NULL){p=p->next;}p->next=new struct active_edge_table; struct active_edge_table *q;q=p->next;q->m=aa.m;q->x=aa.x;q->ymin=aa.ymin;q->next=new struct active_edge_table;q->next->m=bb.m;q->next->ymin=bb.ymin;q->next->x=bb.x;q->next->next=bb.next;}continue;}if(py[j+1]>py[j]&&py[M-2]>py[j])continue;if(py[j+1]>py[j]&&py[M-2]<py[j]){struct active_edge_table bbb;bbb.m=float(px[M-2]-px[j])/(py[M-2]-py[j]);bbb.m=myabs(bbb.m);if(px[M-2]>px[j]) bbb.m=myabs(bbb.m);elsebbb.m=bbb.m*(-1);bbb.x=px[j]+bbb.m;bbb.ymin=py[M-2];bbb.next=NULL;struct active_edge_table *p;if(NET[y-1]==NULL){NET[y-1]=new struct active_edge_table;NET[y-1]->m=bbb.m;NET[y-1]->x=bbb.x;NET[y-1]->ymin=bbb.ymin;NET[y-1]->next=NULL;}else{p=NET[y-1];while(p->next!=NULL){p=p->next;}p->next=new struct active_edge_table;struct active_edge_table *q;q=p->next;q->m=bbb.m;q->x=bbb.x;q->ymin=bbb.ymin;q->next=NULL;}continue;}if(py[j+1]<py[j]&&py[M-2]>py[j]){struct active_edge_table aaa;aaa.m=float(px[j+1]-px[j])/(py[j+1]-py[j]);aaa.m=myabs(aaa.m);if(px[j+1]>px[j]) aaa.m=myabs(aaa.m);else aaa.m=aaa.m*(-1);aaa.x=px[j]+aaa.m;aaa.ymin=py[j+1];aaa.next=NULL;struct active_edge_table *p;if(NET[y-1]==NULL){NET[y-1]=new struct active_edge_table;NET[y-1]->m=aaa.m;NET[y-1]->x=aaa.x;NET[y-1]->ymin=aaa.ymin;NET[y-1]->next=NULL;}else{p=NET[y-1];while(p->next!=NULL){p=p->next;}p->next=new struct active_edge_table;struct active_edge_table *q;q=p->next;q->m=aaa.m;q->x=aaa.x;q->ymin=aaa.ymin;q->next=NULL;}continue;}if(py[j+1]==py[j]&&py[M-2]<py[j]){struct active_edge_table aaa;aaa.m=float(px[M-2]-px[j])/(py[M-2]-py[j]);aaa.m=myabs(aaa.m);if(px[M-2]>px[j]) aaa.m=myabs(aaa.m);else aaa.m=aaa.m*(-1);aaa.x=px[j]+aaa.m;aaa.ymin=py[M-2];aaa.next=NULL;struct active_edge_table *p;if(NET[y-1]==NULL){NET[y-1]=new struct active_edge_table;NET[y-1]->m=aaa.m;NET[y-1]->x=aaa.x;NET[y-1]->ymin=aaa.ymin;NET[y-1]->next=NULL;}else{p=NET[y-1];while(p->next!=NULL){p=p->next;}p->next=new struct active_edge_table;struct active_edge_table *q;q=p->next;q->m=aaa.m;q->x=aaa.x;q->ymin=aaa.ymin;q->next=NULL;}continue;}if(py[j+1]<py[j]&&py[M-2]==py[j]){struct active_edge_table aaa;aaa.m=float(px[j+1]-px[j])/(py[j+1]-py[j]);aaa.m=myabs(aaa.m);if(px[j+1]>px[j]) aaa.m=myabs(aaa.m);else aaa.m=aaa.m*(-1);aaa.x=px[j]+aaa.m;aaa.ymin=py[j+1];aaa.next=NULL;struct active_edge_table *p;if(NET[y-1]==NULL){NET[y-1]=new struct active_edge_table;NET[y-1]->m=aaa.m;NET[y-1]->x=aaa.x;NET[y-1]->ymin=aaa.ymin;NET[y-1]->next=NULL;}else{p=NET[y-1];while(p->next!=NULL){p=p->next;}p->next=new struct active_edge_table;struct active_edge_table *q;q=p->next;q->m=aaa.m;q->x=aaa.x;q->ymin=aaa.ymin;q->next=NULL;}continue;}}if(py[j+1]<py[j]&&py[j-1]<py[j]){ struct active_edge_table aa1;struct active_edge_table bb1;aa1.m=float(px[j+1]-px[j])/(py[j+1]-py[j]);aa1.m=myabs(aa1.m);if(px[j+1]>px[j]) aa1.m=myabs(aa1.m);elseaa1.m=aa1.m*(-1);aa1.x=px[j]+aa1.m;aa1.ymin=py[j+1];bb1.m=float(px[j-1]-px[j])/(py[j-1]-py[j]);bb1.m=myabs(bb1.m);if(px[j-1]>px[j])bb1.m=myabs(bb1.m);elsebb1.m=bb1.m*(-1);bb1.x=px[j]+bb1.m;bb1.ymin=py[j-1];bb1.next=NULL;struct active_edge_table *p;if(NET[y-1]==NULL){NET[y-1]=new struct active_edge_table;NET[y-1]->m=aa1.m;NET[y-1]->x=aa1.x;NET[y-1]->ymin=aa1.ymin;NET[y-1]->next=new struct active_edge_table;NET[y-1]->next->m=bb1.m;NET[y-1]->next->ymin=bb1.ymin;NET[y-1]->next->x=bb1.x;NET[y-1]->next->next=bb1.next;}else{p=NET[y-1];while(p->next!=NULL){p=p->next;}p->next=new struct active_edge_table;struct active_edge_table *q;q=p->next;q->m=aa1.m;q->x=aa1.x;q->ymin=aa1.ymin;q->next=new struct active_edge_table;q->next->m=bb1.m;q->next->ymin=bb1.ymin;q->next->x=bb1.x;q->next->next=bb1.next;}continue;}if(py[j+1]>py[j]&&py[j-1]>py[j])continue;if(py[j+1]>py[j]&&py[j-1]<py[j]){struct active_edge_table bb2;bb2.m=float(px[j-1]-px[j])/(py[j-1]-py[j]);bb2.m=myabs(bb2.m);if(px[j-1]>px[j]) bb2.m=myabs(bb2.m);elsebb2.m=bb2.m*(-1);bb2.x=px[j]+bb2.m;bb2.ymin=py[j-1];bb2.next=NULL;struct active_edge_table *p;if(NET[y-1]==NULL){NET[y-1]=new struct active_edge_table;NET[y-1]->m=bb2.m;NET[y-1]->x=bb2.x;NET[y-1]->ymin=bb2.ymin;NET[y-1]->next=bb2.next;}else{p=NET[y-1];while(p->next!=NULL){p=p->next;}p->next=new struct active_edge_table;struct active_edge_table *q;q=p->next;q->m=bb2.m;q->x=bb2.x;q->ymin=bb2.ymin;q->next=NULL;}continue;}if(py[j+1]<py[j]&&py[j-1]>py[j]){struct active_edge_table aa2;aa2.m=float(px[j+1]-px[j])/(py[j+1]-py[j]);aa2.m=myabs(aa2.m);if(px[j+1]>px[j])aa2.m=myabs(aa2.m);elseaa2.m=aa2.m*(-1);aa2.x=px[j]+aa2.m;aa2.ymin=py[j+1];aa2.next=NULL;struct active_edge_table *p;if(NET[y-1]==NULL){NET[y-1]=new struct active_edge_table;NET[y-1]->m=aa2.m;NET[y-1]->x=aa2.x;NET[y-1]->ymin=aa2.ymin;NET[y-1]->next=aa2.next;}else{p=NET[y-1];while(p->next!=NULL){p=p->next;}p->next=new struct active_edge_table;struct active_edge_table *q;q=p->next;q->m=aa2.m;q->x=aa2.x;q->ymin=aa2.ymin;q->next=NULL;}continue;}if(py[j+1]==py[j]&&py[j-1]<py[j]){struct active_edge_table aaa;aaa.m=float(px[j-1]-px[j])/(py[j-1]-py[j]);aaa.m=myabs(aaa.m);if(px[j-1]>px[j]) aaa.m=myabs(aaa.m);else aaa.m=aaa.m*(-1);aaa.x=px[j]+aaa.m;aaa.ymin=py[j-1];aaa.next=NULL;struct active_edge_table *p;if(NET[y-1]==NULL){NET[y-1]=new struct active_edge_table;NET[y-1]->m=aaa.m;NET[y-1]->x=aaa.x;NET[y-1]->ymin=aaa.ymin;NET[y-1]->next=NULL;}else{p=NET[y-1];while(p->next!=NULL){p=p->next;}p->next=new struct active_edge_table;struct active_edge_table *q;q=p->next;q->m=aaa.m;q->x=aaa.x;q->ymin=aaa.ymin;q->next=NULL;}continue;}if(py[j+1]<py[j]&&py[j-1]==py[j]){struct active_edge_table aaa;aaa.m=float(px[j+1]-px[j])/(py[j+1]-py[j]);aaa.m=myabs(aaa.m);if(px[j+1]>px[j]) aaa.m=myabs(aaa.m);else aaa.m=aaa.m*(-1);aaa.x=px[j]+aaa.m;aaa.ymin=py[j+1];aaa.next=NULL;struct active_edge_table *p;if(NET[y-1]==NULL){NET[y-1]=new struct active_edge_table;NET[y-1]->m=aaa.m;NET[y-1]->x=aaa.x;NET[y-1]->ymin=aaa.ymin;NET[y-1]->next=NULL;}else{p=NET[y-1];while(p->next!=NULL){p=p->next;}p->next=new struct active_edge_table;struct active_edge_table *q;q=p->next;q->m=aaa.m;q->x=aaa.x;q->ymin=aaa.ymin;q->next=NULL;}continue;}}}}//在活化链表中插入一个结点，并排序struct active_edge_table *insert_node(struct active_edge_table *head, struct active_edge_table *stud){struct active_edge_table *p0,*p1,*p2,*p3;p1=head;p0=stud;if(head==NULL){ //活化链表为空p0->next=NULL;head=p0;}else{ //寻找插入位置while((p0->x>p1->x)&&(p1->next!=NULL)){p2=p1;p1=p1->next;}if(p0->x<p1->x){ //当x坐标不等时，按x递增插入排序if(head==p1){ //插入在第一结点之前p0->next=p1;head=p0;}else{ //非尾结点插入p2->next=p0;p0->next=p1;}}else if(p0->x==p1->x){ //当x坐标相等时，可能遇到两条线段有相同的x坐标，按m递增插入排序if(p0->m < p1->m){p2->next=p0;p0->next=p1;}else{p3=p1->next;p1->next=p0;p0->next=p3;}}else{p0->next=NULL; //结点插到表尾p1->next=p0;}}return(head);}//从活化边表中删除一个结点struct active_edge_table * del_node(struct active_edge_table * head,int ys){struct active_edge_table *p1,*p2=NULL;p1=head;do{if(ys==p1->ymin){if(p1==head){head=p1->next; p1=p1->next;}else{p2->next=p1->next;p1=p2->next;}}else{p2=p1;p1=p1->next;}}while(p1!=NULL);return(head);}void init(void){glClearColor (1.0, 1.0, 1.0, 0.0);glClear (GL_COLOR_BUFFER_BIT);glClear (GL_COLOR_BUFFER_BIT);}void polyScanFill (void){int i,ymin,ymax;struct active_edge_table *p=NULL,*q=NULL,*aet_head=NULL;//int px[M]={100,100,240,380,460,300,200,100};//int py[M]={140,240,160,260,120, 80, 80,140};//int px[M]={100,100,240,380,400,460,300,100};//int py[M]={140,240,160,260,120,120, 80,140};//int px[M]={100,100,200,200,300,250,130,100};//int py[M]={140,240,240,140,100,80, 80,140};int px[M]={100,100,200,200,300,250,130,100};int py[M]={140,240,240,140,140,80, 80,140};ymin=y_min(py);ymax=y_max(py);min=ymin;max=ymax;for(i=ymin;i<=maxy;i++)NET[i]=NULL; //将新边表数组初始化为空指针polyNet(px, py);for(i=ymax;i>=ymin;i--){ //逐条扫描线填充if(NET[i]!=NULL){ //如果有新边加入，插入活化边表，并排序p=NET[i]; q=p;while(q){q=p->next;aet_head=insert_node(aet_head,p);p=q;}}if(aet_head!=NULL){ //对活化边表线段进行填充glColor3f (0.0, 0.0, 1.0);p=aet_head;q=p->next;glBegin(GL_LINES);glVertex2i(ROUND(p->x),i);glVertex2i(ROUND(q->x),i);glEnd();while((q->next)!=NULL){p=q->next;q=p->next;glBegin(GL_LINES);glVertex2i(ROUND(p->x),i);glVertex2i(ROUND(q->x),i);glEnd();}aet_head=del_node(aet_head,i);p=aet_head;while(p){p->x=p->x+p->m;p=p->next;}//Sleep(10);} //if(aet_head)}glColor3f (1.0, 0.0, 0.0);glLineWidth(2.0);glBegin(GL_LINE_LOOP);for(i=0;i<M-1;i++){glVertex2i(px[i],py[i]);}glEnd();glFlush ( );}void winReshapeFcn (int newWidth, int newHeight){glMatrixMode (GL_PROJECTION);glLoadIdentity ( );gluOrtho2D (0.0, (GLdouble) newWidth, 0.0, (GLdouble) newHeight);}void main (int argc, char** argv){glutInit (&argc, argv);glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);glutInitWindowPosition (100, 100);glutInitWindowSize (winWidth, winHeight);glutCreateWindow ("Polygon scaning fill program!");init();glutReshapeFunc (winReshapeFcn);glutDisplayFunc (polyScanFill);glutMainLoop ( );}