CONCENTRIC CIRCLE ANIMATION

#include <allegro.h>
#define R makecol(255,0,0)
#define G makecol(0,255,0)
#define B makecol(0,0,255)
#define K makecol(0,0,0)
#define W makecol(255,255,255)


float inner_circ_angle=0;
float cx=0,cy=0;
float sx=0,sy=0;
float r=30,angle=0;//rotating circle

BITMAP *buffer;

int draw_main_circles();
int draw_rotating_circles();


int main()
{   

   
    //int cirnum=0;
    //int rx=0,ry=0;//to detect the sign of directions
    //int dir=0;
   
   
   
    allegro_init();
    install_keyboard();
   
    set_color_depth(32);
    set_gfx_mode(GFX_AUTODETECT_WINDOWED, 800, 600, 0, 0);
    buffer=create_bitmap(SCREEN_W,SCREEN_H);
   
    cx=SCREEN_W/2;
    cy=SCREEN_H/2;
    //layernum=2;//one layer
   
   
    while(!key[KEY_ESC])
    {
                        draw_main_circles();
                       
                        //circle(buffer,cx,cy,r,K);
                        //draw_rotating_circles();
                         blit(buffer,screen,0,0,0,0,buffer->w,buffer->h);
                        clear_to_color(buffer,K);
                      
                        rest(100);
                        }
                       
                        destroy_bitmap(buffer);
                       
                        allegro_exit();
                       
                        }END_OF_MAIN();
                       
                        int  draw_main_circles()
                        {
                             int i=0,j=0;
                             int tx=0,ty=0;
                             //for main circle
                             circle(buffer,cx,cy,r,G);
                             //tx=cx+r*cos(inner_circ_angle);
                             //ty=cy+r*sin(inner_circ_angle);
                            
                             //circlefill(buffer,tx,ty,4,K);
                            
                             for(j=0;j<10;j++)
                             {
                             for(i=0;i<=10;i++)
                             {
                                              tx=cx+(j*r)*cos(i*36);
                                              ty=cy+(j*r)*sin(i*36);
                                              circle(buffer,tx,ty,r,G);
                                             
                                              //calculating for sub circle
                                              sx=tx+r*cos(inner_circ_angle);
                                              sy=ty+r*sin(inner_circ_angle);
                                              circlefill(buffer,sx,sy,3,makecol(rand()%255,rand()%255,rand()%255));
                                              inner_circ_angle+=0.1;
                                             
                                              }
                                              if(j>=10) j=0;
                                              if(inner_circ_angle>=360) inner_circ_angle=0;
                                             
                                              }
                                              return 1;
                                             
                                              }//end for main-circles drawing
                                             

/*int  draw_rotating_circles()
{
     sx=cx+r*cos(inner_circ_angle);
     sy=cy+r*sin(inner_circ_angle);
     inner_circ_angle++;
     circlefill(buffer,sx,sy,3,R);
     blit(buffer,screen,0,0,0,0,buffer->w,buffer->h);
    
     //inner_circ_angle++;
     if(inner_circ_angle>=360)
      inner_circ_angle=0;
     
      return 1;
     }*/