# include <iostream.h> # include <graphics.h> # include <conio.h> # include <math.h> class PointCoordinates { public: float x; float y; PointCoordinates( ) { x=0; y=0; } }; //--------------------------- LineCoordinates -------------------------// class LineCoordinates { public: float x_1; float y_1; float x_2; float y_2; LineCoordinates( ) { x_1=0; y_1=0; x_2=0; y_2=0; } LineCoordinates(const float x1,const float y1, const float x2,const float y2) { x_1=x1; y_1=y1; x_2=x2; y_2=y2; } }; //------------------------- WindowCoordinates -------------------------// class WindowCoordinates { public: float x_min; float y_min; float x_max; float y_max; WindowCoordinates(const float x1,const float y1, const float x2,const float y2) { x_min=x1; y_min=y1; x_max=x2; y_max=y2; } }; void show_screen( ); void clip_polygon(const WindowCoordinates,const int,const int []); const int check_line(const LineCoordinates,const LineCoordinates); const int check_point(const LineCoordinates,const float,const float); const PointCoordinates get_intersection_point(LineCoordinates, LineCoordinates); void Polygon(const int,const int []); void Rectangle(const int,const int,const int,const int); void Line(const int,const int,const int,const int); int main( ) { int driver=VGA; int mode=VGAHI; initgraph(&driver,&mode,\"..\\\\Bgi\"); show_screen( ); WindowCoordinates WC(180,140,470,340); setcolor(15); Rectangle(WC.x_min,WC.y_min,WC.x_max,WC.y_max); int n=10; int polygon_vertices[20]={ 100,240 , 180,370 , 210,310 , 380,375 , 520,310 , 480,260 , 510,80 , 280,180 , 210,90 , 100,240 }; setcolor(7); Polygon(n,polygon_vertices); setcolor(15); settextstyle(0,0,1); outtextxy(300,240,\"Window\"); outtextxy(80,240,\"Polygon\"); char Key=NULL; do { Key=getch( ); } while(Key!=\'C\' && Key!=\'c\'); settextstyle(0,0,1); setcolor(0); outtextxy(163,450,\" Press \'C\' to see the Clipped Polygon. \"); setcolor(15); outtextxy(163,450,\"------ ---------\"); setcolor(12); outtextxy(213,450,\" Press any Key to exit. \"); clip_polygon(WC,n,polygon_vertices); setcolor(15); settextstyle(0,0,1); outtextxy(280,155,\"Clipped Polygon\"); getch( ); return 0; } //-------------------------- clip_polygon( ) --------------------------// void clip_polygon(const WindowCoordinates wc,const int n, const int polygon_edges[]) { int edges_counter; int number_of_edges=n; int *edges=new int[(n*4)]; int *clipped_edges=new int[(n*4)]; for(int count_1=0;count_1<(n*2);count_1++) edges[count_1]=polygon_edges[count_1]; LineCoordinates window_line; for(int count_2=1;count_2<=4;count_2++) { edges_counter=1; for(int count_3=0;count_3<(number_of_edges*4);count_3++) clipped_edges[count_3]=0; if(count_2==1) { window_line.x_1=wc.x_min; window_line.y_1=wc.y_max; window_line.x_2=wc.x_max; window_line.y_2=wc.y_max; } else if(count_2==2) { window_line.x_1=wc.x_max; window_line.y_1=wc.y_max; window_line.x_2=wc.x_max; window_line.y_2=wc.y_min; } else if(count_2==3) { window_line.x_1=wc.x_max; window_line.y_1=wc.y_min; window_line.x_2=wc.x_min; window_line.y_2=wc.y_min; } else if(count_2==4) { window_line.x_1=wc.x_min; window_line.y_1=wc.y_min; window_line.x_2=wc.x_min; window_line.y_2=wc.y_max; } int rule_no; PointCoordinates point; for(int count_4=1;count_4<number_of_edges;count_4++) { LineCoordinates line(edges[((count_4*2)-2)], edges[((count_4*2)-1)], edges[(count_4*2)], edges[((count_4*2)+1)]); rule_no=check_line(window_line,line); switch(rule_no) { case 1 : clipped_edges[(edges_counter*2)]= (int)(line.x_2+0.5); clipped_edges[((edges_counter*2)+1)]= (int)(line.y_2+0.5); edges_counter++; break; case 2 : break; case 3 : point= get_intersection_point(window_line,line); clipped_edges[(edges_counter*2)]= (int)(point.x+0.5); clipped_edges[((edges_counter*2)+1)]= (int)(point.y+0.5); edges_counter++; break; case 4 : point= get_intersection_point(window_line,line); clipped_edges[(edges_counter*2)]= (int)(point.x+0.5); clipped_edges[((edges_counter*2)+1)]= (int)(point.y+0.5); edges_counter++; clipped_edges[(edges_counter*2)]= (int)(line.x_2+0.5); clipped_edges[((edges_counter*2)+1)]= (int)(line.y_2+0.5); edges_counter++; break; } } clipped_edges[0]=clipped_edges[((edges_counter*2)-2)]; clipped_edges[1]=clipped_edges[((edges_counter*2)-1)]; for(int count_5=0;count_5<(edges_counter*2);count_5++) edges[count_5]=0; number_of_edges=edges_counter; for(int count_6=0;count_6<(edges_counter*2);count_6++) edges[count_6]=clipped_edges[count_6]; } setcolor(10); Polygon(number_of_edges,edges); delete edges; delete clipped_edges; } //---------------------------- check_line( ) --------------------------// const int check_line(const LineCoordinates line,const LineCoordinates edge) { int rule_number=0; int point_1=check_point(line,edge.x_1,edge.y_1); int point_2=check_point(line,edge.x_2,edge.y_2); if(point_1==1 && point_2==1) rule_number=1; else if(point_1!=1 && point_2!=1) rule_number=2; else if(point_1==1 && point_2!=1) rule_number=3; else if(point_1!=1 && point_2==1) rule_number=4; return rule_number; } //---------------------------- check_point( ) -------------------------// const int check_point(const LineCoordinates lc,const float x,const float y) { float c=(((lc.x_2-lc.x_1)*(y-lc.y_1))-((lc.y_2-lc.y_1)*(x-lc.x_1))); if(c<=0) return 1; else return 0; } //---------------------- get_intersection_point( ) --------------------// const PointCoordinates get_intersection_point(LineCoordinates lc1, LineCoordinates lc2) { float x_min=lc1.x_1; float x_max=lc1.x_2; float y_min=lc1.y_1; float y_max=lc1.y_2; if(lc1.x_1==lc1.x_2) { if(lc2.y_2>=lc2.y_1 && lc2.y_2>y_max) y_max=lc2.y_2; else if(lc2.y_1>lc2.y_2 && lc2.y_1>y_max) y_max=lc2.y_1; if(lc2.y_1<=lc2.y_2 && lc2.y_1<y_min) y_min=lc2.y_1; else if(lc2.y_2<lc2.y_1 && lc2.y_2<y_min) y_min=lc2.y_2; } else if(lc1.y_1==lc1.y_2) { if(lc2.x_2>=lc2.x_1 && lc2.x_2>x_max) x_max=lc2.x_2; else if(lc2.x_2<lc2.x_1 && lc2.x_1>x_max) x_max=lc2.x_1; if(lc2.x_1<=lc2.x_2 && lc2.x_1<x_min) x_min=lc2.x_1; else if(lc2.x_2<lc2.x_1 && lc2.x_2<x_min) x_min=lc2.x_2; } float x_mid; float y_mid; if(lc2.y_1>y_max) { while(lc2.y_1!=y_max) { x_mid=((lc2.x_1+lc2.x_2)/2); y_mid=((lc2.y_1+lc2.y_2)/2); if(y_mid>=y_max) { lc2.x_1=x_mid; lc2.y_1=y_mid; } else { lc2.x_2=x_mid; lc2.y_2=y_mid; } } } else if(lc2.y_1<y_min) { while(lc2.y_1!=y_min) { x_mid=((lc2.x_1+lc2.x_2)/2); y_mid=((lc2.y_1+lc2.y_2)/2); if(y_mid<=y_min) { lc2.x_1=x_mid; lc2.y_1=y_mid; } else { lc2.x_2=x_mid; lc2.y_2=y_mid; } } } if(lc2.x_1>x_max) { while(lc2.x_1!=x_max) { x_mid=((lc2.x_1+lc2.x_2)/2); y_mid=((lc2.y_1+lc2.y_2)/2); if(x_mid>=x_max) { lc2.x_1=x_mid; lc2.y_1=y_mid; } else { lc2.x_2=x_mid; lc2.y_2=y_mid; } } } else if(lc2.x_1<x_min) { while(lc2.x_1!=x_min) { x_mid=((lc2.x_1+lc2.x_2)/2); y_mid=((lc2.y_1+lc2.y_2)/2); if(x_mid<=x_min) { lc2.x_1=x_mid; lc2.y_1=y_mid; } else { lc2.x_2=x_mid; lc2.y_2=y_mid; } } } PointCoordinates ipt; ipt.x=lc2.x_1; ipt.y=lc2.y_1; return ipt; } //--------------------------- Rectangle( ) ----------------------------// void Rectangle(const int x_1,const int y_1,const int x_2,const int y_2) { Line(x_1,y_1,x_2,y_1); Line(x_2,y_1,x_2,y_2); Line(x_2,y_2,x_1,y_2); Line(x_1,y_2,x_1,y_1); } //----------------------------- Polygon( ) ----------------------------// void Polygon(const int n,const int coordinates[]) { if(n>=2) { Line(coordinates[0],coordinates[1], coordinates[2],coordinates[3]); for(int count=1;count<(n-1);count++) Line(coordinates[(count*2)],coordinates[((count*2)+1)], coordinates[((count+1)*2)], coordinates[(((count+1)*2)+1)]); } } //-------------------------- Line( ) ------------------------// void Line(const int x_1,const int y_1,const int x_2,const int y_2) { int color=getcolor( ); int x1=x_1; int y1=y_1; int x2=x_2; int y2=y_2; if(x_1>x_2) { x1=x_2; y1=y_2; x2=x_1; y2=y_1; } int dx=abs(x2-x1); int dy=abs(y2-y1); int inc_dec=((y2>=y1)?1:-1); if(dx>dy) { int two_dy=(2*dy); int two_dy_dx=(2*(dy-dx)); int p=((2*dy)-dx); int x=x1; int y=y1; putpixel(x,y,color); while(x<x2) { x++; if(p<0) p+=two_dy; else { y+=inc_dec; p+=two_dy_dx; } putpixel(x,y,color); } } else { int two_dx=(2*dx); int two_dx_dy=(2*(dx-dy)); int p=((2*dx)-dy); int x=x1; int y=y1; putpixel(x,y,color); while(y!=y2) { y+=inc_dec; if(p<0) p+=two_dx; else { x++; p+=two_dx_dy; } putpixel(x,y,color); } } } //-------------------------- show_screen( ) ---------------------------// void show_screen( ) { setfillstyle(1,1); bar(125,26,510,38); settextstyle(0,0,1); setcolor(15); outtextxy(5,5,\"******************************************************************************\"); outtextxy(5,17,\"*-**************************************************************************-*\"); outtextxy(5,29,\"*------------- -------------*\"); outtextxy(5,41,\"*-**************************************************************************-*\"); outtextxy(5,53,\"*-**************************************************************************-*\"); setcolor(11); outtextxy(134,29,\"Sutherland-Hodgeman Polygon Clipping Algorithm\"); setcolor(15); for(int count=0;count<=30;count++) outtextxy(5,(65+(count*12)),\"*-* *-*\"); outtextxy(5,438,\"*-**************************************************************************-*\"); outtextxy(5,450,\"*------------------- ----------------*\"); outtextxy(5,462,\"******************************************************************************\"); setcolor(12); outtextxy(163,450,\" Press \'C\' to see the Clipped Polygon. \"); }