Implementation of curve drawing using Bezier algorithm

1. #include<dos.h>
2. #include<stdio.h>
3. #include<iostream.h>
4. #include<graphics.h>
5. #include<conio.h>
6. int a[150],b[150],m,n=0,j,d; float bx[5000],by[5000],u; union REGS i,o;
7. initmouse()
8. {
9. i.x.ax=0; int86(0x33,&i,&o); return(o.x.ax);
10. }
11. void showmouseptr()
12. {
13. i.x.ax=1; int86(0x33,&i,&o);
14. }
15. void getmousepos(int *button,int *x,int *y)
16. {
17. i.x.ax=3; int86(0x33,&i,&o);
18. *button=o.x.bx;
19. *x=o.x.cx;
20. *y=o.x.dx; i.h.ah=0x02; i.h.dh=0;
21.  
22. 
    
23. 
    
24. i.h.dl=0;  int86(0x10,&i,&o);  cout<<"X: "<<*x<<" Y: "<<*y; i.h.ah=0x02; int86(0x10,&i,&o);
25. }
26. void hidemouseptr()
27. {
28. i.x.ax=2; int86(0x33,&i,&o);
29. }
30. int compco()
31. {
32. int k,coeff=1;
33. for(k=d+1;k<=n;k++) coeff=coeff*k; for(k=2;k<=n-d;k++) coeff=coeff/k; return coeff;
34. }
35. float blenval()
36. {
37. int k;
38. float blend; blend=compco();
39. for(k=1;k<=d;k++) blend=blend*u; for(k=1;k<=n-d;k++) blend=blend*(1.0-u); return blend;
40. }
41. void bezier()
42. {
43. float blend1;
44.  
45. 
    
46. 
    
47. bx[j]=0;by[j]=0; for(d=0;d<=n;d++)
48. {
49. blend1=blenval(); bx[j]+=a[d]*blend1; by[j]+=b[d]*blend1;
50. }
51. }
52. void curve()
53. {
54. for(j=0;j<m;j++) putpixel(bx[j],by[j],GREEN);
55. }
56. void drawi()
57. {
58. for(j=0;j<=m;j++)
59. {
60. u=(float)j/m; bezier();
61. }
62. curve();
63. }
64. void main()
65. {
66. int gd=DETECT,gm; int button,tx,ty; clrscr();  m=4990;
67. flushall(); initgraph(&gd,&gm,"c:\\tc\\bgi"); cleardevice();
68.  
69. 
    
70. 
    
71. showmouseptr(); while(!kbhit())
72. {
73. getmousepos(&button,&tx,&ty); if((button & 1) == 1)
74. {
75. hidemouseptr(); setcolor(WHITE); a[n]=tx;
76. b[n]=ty; putpixel(tx,ty,WHITE); circle(tx,ty,2);
77. n++;
78. delay(50); showmouseptr();
79. }
80. }
81. n--;
82. drawi();
83. getch();
84. }

Output: