Club Amiga de Montreal - CAM/CAM_CD_1.iso/files/545a.lha/bezier_v0.0001/bezier.c

C/C++ Source or Header | 1991-09-07 | 3.8 KB | 208 lines

/*bezier.c*/

#define MAXPTS 2000        /* sets max # points to read */
#define MAXBEZ 2000        /* sets max # points to write */

/*#include <m68881.h>*/        /* include for math coprocessor */
#include <math.h>
#include <stdio.h>
#include <string.h>

unsigned short int cnt=0,numpnts=0;
static double outarr[MAXBEZ][2];


main(argc,argv)
char *argv[];
{

double array[MAXPTS][2];
unsigned short int q,pstat=0,wb=1;

FILE *infile=stdin,*outfile=stdout,*fopen();

    if(argc==1)
        {
        fprintf(stderr," Use: %s [-nod] <# BezPoints> [infile][outfile]\n",argv[0]);
        exit(20);
        }
    for(q=1;q<argc;q++)
        {
        if(strncmp(argv[q],"-nod",4)==0)    /* this option allows files without DATA statement */
            {
            wb=0;
            continue;
            }
        else if(pstat==0)
            {
            if(sscanf(argv[q],"%hd",&numpnts)!=1)    /* number of points to generate */
                {
                fprintf(stderr," Strange number!\n");
                exit(20);
                }
            else ++pstat;
            }
        else if(pstat==1)
            {
            if((infile=fopen(argv[q],"r"))==NULL)
                {
                fprintf(stderr," %s cant open file %s for read\n",argv[0],argv[q]);
                exit(20);
                }
            else ++pstat;
            }
        else if(pstat==2)
            {
            if((outfile=fopen(argv[q],"w"))==NULL)
                {
                fprintf(stderr," %s cant open file %s for write\n",argv[0],argv[q]);
                exit(20);
                }
            else ++pstat;
            }
        }


    ReadData(infile,array,&cnt,wb);
    if(cnt==0)
        {
        fprintf(stderr," %s problem reading data\n",argv[0]);
        exit(20);
        }
    else fprintf(stderr," %s read %hd data pairs\n",argv[0],cnt);

    if(infile)fclose(infile);

    CalcBez(array,outarr,cnt,&numpnts);

    WriteData(outfile,outarr,numpnts,wb);

    fprintf(stderr,"\n %s wrote %hd data pairs\n",argv[0],numpnts);

    if(outfile)fclose(outfile);
    exit(0);
}



ReadData(ifp,data,count,byers)    /* this routine reads xy data pairs into array */

unsigned short int *count,byers;
double data[MAXPTS][2];
FILE *ifp;

{

register unsigned short int ctr;
char cm,key[50];

    while(byers)                /* if true search for keyword DATA */
        {                    /* Byers is the twisted person who requires this format */

        if(fscanf(ifp,"%s",key)!=1)
            {
            fprintf(stderr," keyword DATA not found!\n");
            exit(20);
            }
        if(strcmp("DATA",key)==0)break;
        }

    for(ctr=0;ctr<MAXPTS;ctr++)
        if(fscanf(ifp,"%lf%c%lf",&data[ctr][0],&cm,&data[ctr][1])!=3)break;
    if(ctr==MAXPTS)fprintf(stderr," MAXPTS reached exiting ReadData\n");
    *count=ctr;
    return(0);
}


WriteData(ofp,bezdat,numb,byers)    /* this function writes array to file da */

unsigned short int numb,byers;
double bezdat[MAXBEZ][2];
FILE *ofp;

{
register unsigned short int q;

    if(byers)fprintf(ofp," DATA\n");
    for(q=0;q<numb;q++)fprintf(ofp,"%-14le%15le\n",bezdat[q][0],bezdat[q][1]);
    return(0);
}




CalcBez(orgarr,bezarr,orgcnt,bezcnt)    /* this function calculates an array of */
                                /* bezier points from the orginal array */
unsigned short int *bezcnt,orgcnt;
double orgarr[MAXPTS][2], bezarr[MAXBEZ][2];

{
register unsigned short int i,j,k,n;

double t,step,mr[MAXPTS];
double coef[MAXPTS];


    if(*bezcnt>MAXBEZ)
        {
            *bezcnt=MAXBEZ;
            fprintf(stderr," bezpnts set to MAXBEZ\n");
        }

    CalcCoef(orgcnt,coef);

    n=orgcnt-1;
    k=1;

    step=1.0/(*bezcnt-1);

    for(j=0;j<2;j++)bezarr[0][j]=orgarr[0][j];

    for(t=step;t<=1.0;t+=step)        /* The big loop */
        {
        fprintf(stderr,"  t == %.3lf\r",t);

        for(i=0;i<=n;i++)
            {
            mr[i]=coef[i]*pow((1.0-t),(double)(n-i))*pow(t,(double)i);
            for(j=0;j<2;j++)bezarr[k][j]+=mr[i]*orgarr[i][j];
            }
        k++;
        }

    for(j=0;j<2;j++)bezarr[k][j]=orgarr[n][j];k++;

    return(0);
}



CalcCoef(numpts,coarr)    /* this function calcs coeficients from Pascals triangle */

unsigned short int numpts;
double coarr[MAXPTS];

{
register unsigned short int y,z;
static double temparr[MAXPTS];

    coarr[0]=coarr[1]=temparr[0]=1.0;

    for(y=1;y<=numpts;y++)
        {
        for(z=1;z<y;z++)temparr[z]=coarr[z-1]+coarr[z];
        for(z=1;z<=y;z++)coarr[z]=temparr[z];
        }
    return(0);
}