main.cpp
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/* Define the structure to store the edges*/ #include<iostream.h> #include<conio.h> #include<graphics.h> struct edge{ int x1,y1,x2,y2,flag;}; int main(){ int gd=DETECT,gm,n,i,j,k; struct edge ed[10],temped; float dx,dy,m[10],x_int[10],inter_x[10]; int x[10],y[10],ymax=0,ymin=480,yy,temp; initgraph(&gd,&gm,””); /*read the number of vertices of the polygon*/ cout<<“Enter the no.of vertices of the graph :”; cin>>n; /*read the vertices of the polygon and also find ymax and ymin*/ cout<<“Enter the vertices”; for(i=0;i<n;i++) { // cout<<x[i]; cin>>x[i]; //cout<<y[i]; cin>>y[i]; if(y[i]>ymax) ymax=y[i]; if(y[i]<ymin) ymin=y[i]; ed[i].x1=x[i]; ed[i].y1=y[i]; } /*store the edge information*/ for(i=0;i<n-1;i++)////////////// { ed[i].x2=ed[i+1].x1; ed[i].y2=ed[i+1].y1; ed[i].flag=0;} ed[i].x2=ed[0].x1; ed[i].y2=ed[0].y1; ed[i].flag=0; /*Check for y1>y2, if not interchnge y1 and y2 */ for(i=0;i<n;i++){ if(ed[i].y1 < ed[i].y2) { temp=ed[i].x1; ed[i].x1=ed[i].x2;///////////// ed[i].x2=temp; temp=ed[i].y1; ed[i].y1=ed[i].y2; ed[i].y2=temp;}} /*Draw the polygon*/ for(i=0;i<n;i++){ line(ed[i].x1, ed[i].y1,ed[i].x2,ed[i].y2);} /*sorting of edges in the order of y1,y2,x1*/ for(i=0;i<n-1;i++){ for(j=0;j<n-1;j++) { if(ed[j].y1<ed[j+1].y1) { temped=ed[j]; ed[j]=ed[j+1]; ed[j+1]=temped;} if(ed[j].y1==ed[j+1].y1) { if(ed[j].y2<ed[j+1].y2) { temped=ed[j]; ed[j]=ed[j+1]; ed[j+1]=temped;} if (ed[j].y2==ed[j+1].y2){ if(ed[j].x1<ed[j+1].x1) { temped=ed[j]; ed[j]=ed[j+1]; ed[j+1]=temped; } } }} } /*calculating 1/slope of each edge and storing top*/ for(i=0;i<n;i++){ dx=ed[i].x2-ed[i].x1; dy=ed[i].y2-ed[i].y1; if(dy==0){ m[i]=0;} else { m[i]=dx/dy; } inter_x[i]=ed[i].x1;} /*making the Actual edges*/ yy=ymax; while(yy>ymin){ for(i=0;i<n;i++) { if(yy>ed[i].y2 && yy<=ed[i].y1) { ed[i].flag=1; } else ed[i].flag=0;} j=0; for(i=0;i<n;i++){ if(ed[i].flag==1){ if(yy==ed[i].y1){ x_int[j]==ed[i].x1; j++; if(ed[i-1].y1==yy && ed[i-1].y1<yy) { x_int[j]=ed[i].x1; j++; } if(ed[i+1].y1==yy && ed[i+1].y1<yy){ x_int[j]=ed[i].x1; j++; }} else { x_int[j]=inter_x[i]+(-m[i]); inter_x[i]=x_int[j]; j++; } }} /*sorting the x intersaction*/ for(i=0;i<j;i++) { for(k=0;k<j-1;k++) { if(x_int[k]>x_int[k+1]) { temp=(int)x_int[k]; x_int[k]=x_int[k+1]; x_int[k+1]=temp; } } } /*extracting pairs of values to draw lilnes*/ for(i=0;i<j;i=i+2) { line((int)x_int[i],yy,(int)x_int[i+1],yy); } yy–; delay(50); } getch(); closegraph(); } |
