/* Input  file : *.bmp                              */
/* Output file : *-sp_l.bmp                         */
/* This program was made introducing the programs   */
/* appeared in the book, "C gengo de manabu jissen  */
/* gazou shori," S.Inoue(eds.),Ohmsha:TOKYO,2002,   */
/* by Shusaku Nomura,2006, Shojiro Tanaka, 2007     */

#include <stdio.h>
#include <stdlib.h>
#pragma pack(push,1)

#include <math.h>

#define PI 3.141592

typedef struct tagBITMAPFILEHEADER{
   short   bfType;
   long   bfSize;
   short   bfReserved1;
   short   bfReserved2;
   long   bfOffBits;
} BITMAPFILEHEADER;

typedef struct tagBITMAPINFOHEADER{
   long   biSize;
   long   biWidth;
   long   biHeight;
   short   biPlanes;
   short   biBitCount;
   long   biCompression;
   long   biSizeImage;
   long   biXPelsPerMeter;
   long   biYPelsPerMeter;
   long   biClrUsed;
   long   biClrImportant;
} BITMAPINFOHEADER;

typedef struct tagRGBTRIPLE {
   unsigned char   RGB[3];/*0:blue, 1:Green, 2:Red*/
} RGBTRIPLE;

RGBTRIPLE*   readBMP(char filename[256],BITMAPFILEHEADER   *bfile,BITMAPINFOHEADER *binfo){
   FILE   *fp;
   RGBTRIPLE   *RGB;
   char   d,buf[4];
   int    i;

   if((fp=fopen(filename,"rb"))==NULL){
      fprintf(stderr,"file open error:%s\n",filename);
      return NULL;
   }
   fread(bfile,sizeof(*bfile),1,fp);
   fread(binfo,sizeof(*binfo),1,fp);

   if(bfile->bfType != 0x4d42){
      fprintf(stderr,"error:file type\n");
      return NULL;
   }
   if(binfo->biBitCount != 24){
      fprintf(stderr,"error:bit Count\n");
      return NULL;
   }

   if((d=((binfo->biWidth*3)%4))==0)
      d=0;
   else
      d=4-d;
   RGB =(RGBTRIPLE*)malloc(sizeof(RGBTRIPLE)*binfo->biWidth*binfo->biHeight);

   if(RGB==NULL){
      fprintf(stderr,"--memory allocation error !\n");
      return NULL;
   }

   for(i=0;i<binfo->biHeight;i++){
      fread(RGB+binfo->biWidth*i,sizeof(RGBTRIPLE),binfo->biWidth,fp);
      fread(buf,1,d,fp);
   }
   fclose(fp);
   return RGB;
}

int   writeBMP(char filename[256],BITMAPFILEHEADER   bfile,BITMAPINFOHEADER binfo,RGBTRIPLE   *RGB){
   FILE   *fp;
   char   d,buf[4]={0,0,0,0};
   int      i;

   if(RGB == NULL){
      return 0;
   }
   /*ファイルの書き出し*/
   if((fp=fopen(filename,"wb"))==NULL){
      fprintf(stderr,"file open error:%s\n",filename);
      return   0;
   }
   if((d=(binfo.biWidth*3)%4)==0)
      d=0;
   else
      d=4-d;

   fwrite(&bfile,sizeof(bfile),1,fp);
   fwrite(&binfo,sizeof(binfo),1,fp);
   for(i=0;i<binfo.biHeight;i++){
      fwrite(RGB+binfo.biWidth*i,sizeof(RGBTRIPLE),binfo.biWidth,fp);
      fwrite(buf,1,d,fp);
   }
   fclose(fp);
   return 1;
}

RGBTRIPLE*   sphere(BITMAPINFOHEADER binfo,RGBTRIPLE   *RGB_in,int cx,int cy,float r,int back){
   int         i,j,k,m,n;
   double rad;
   float x,y,p,q;
   int flag;
   int         d;
   RGBTRIPLE   *RGB_out;

   if(RGB_in == NULL){
      return NULL;
   }

   RGB_out=(RGBTRIPLE*)malloc(sizeof(RGBTRIPLE)*binfo.biWidth*binfo.biHeight);
   if(RGB_out == NULL){
      fprintf(stderr,"--memory allocation error !\n");
      return NULL;
     }
   for(i=-cy;i<binfo.biHeight-cy;i++){
      for(j=-cx;j<binfo.biWidth-cx;j++){
           flag=0;
         rad=sqrt(i*i+j*j);

         if(rad == 0){
            x=y=0;
         }else if((double)(i*i+j*j)<r*r){
            y=(i/rad)*r*asin(rad/r);
            x=(j/rad)*r*asin(rad/r);
         }else{
            y=i;
            x=j;
            flag=1;
         }
        if(y>=0)
            m=(int)(y);
         else
            m=(int)(y-1);
         if(x>=0)
            n=(int)(x);
         else
            n=(int)(x-1);
       q=y-m;
       p=x-n;
       if(p==1){
            p=0;n=n+1;
         }
         if((m+1+cy)>=(binfo.biHeight))
            m=m-1;
         if((n+1+cx)>=(binfo.biWidth))
            n=n-1;

         for(k=0;k<3;k++){
          if((0<=(m+cy))&&((m+cy)<binfo.biHeight)&&(0 <= (n+cx))&&((n+cx)<binfo.biWidth)){
               d=(int)((1.0-q)*((1.0-p)*RGB_in[(m+cy)*binfo.biWidth+(n+cx)].RGB[k]
                      +p*RGB_in[(m+cy)*binfo.biWidth+(n+1+cx)].RGB[k])
                      +q*((1.0-p)*RGB_in[(m+1+cy)*binfo.biWidth+(n+cx)].RGB[k]
                      +p*RGB_in[(m+1+cy)*binfo.biWidth+(n+1+cx)].RGB[k]));
          }else{
            d=0;
          }
            if(d<0)
               d=0;
            if(d>255)
               d=255;
         if(flag==0 || back==1)
               RGB_out[binfo.biWidth*(i+cy)+(j+cx)].RGB[k]=d;
            else
               RGB_out[binfo.biWidth*(i+cy)+(j+cx)].RGB[k]=0;
         }
      }
   }
   return RGB_out;
}

int main(){
   char   str[256],filename[256];

   BITMAPFILEHEADER   bfile;
   BITMAPINFOHEADER   binfo;
   RGBTRIPLE   *RGB_in,*RGB_out;
   float   r;
   int   x,y;

   puts("input filename");
   scanf("%s",str);
   sprintf(filename,"%s.bmp\0",str);

   if((RGB_in=readBMP(filename,&bfile,&binfo))==NULL)
      return 0;
   printf("Input:%s width:%d,height:%d\n",filename,binfo.biWidth,binfo.biHeight);

   printf("center = x,y  ?:");
   scanf("%d %d",&x,&y);
   printf("radius: (float) ?:");
   scanf("%f",&r);


   RGB_out=sphere(binfo,RGB_in,x,y,r,0);

   sprintf(filename,"%s-sp_l.bmp\0",str);
   printf("Output:%s \n",filename);

   writeBMP(filename,bfile,binfo,RGB_out);

   free(RGB_in);
   free(RGB_out);
   return 0;
}