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gensurf.c

#ifndef lint
static const char RCSid[] = "$Id: gensurf.c,v 2.18 2007/10/18 03:59:54 greg Exp $";
#endif
/*
 *  gensurf.c - program to generate functional surfaces
 *
 *    Parametric functions x(s,t), y(s,t) and z(s,t)
 *  specify the surface, which is tesselated into an m by n
 *  array of paired triangles.
 *    The surface normal is defined by the right hand
 *  rule applied to (s,t).
 *
 *    4/3/87
 *
 *    4/16/02     Added conditional vertex output
 */

#include  "standard.h"

#include  "paths.h"
#include  "resolu.h"
#include  "rterror.h"
#include  "calcomp.h"

char  XNAME[] =         "X`SYS";          /* x function name */
char  YNAME[] =         "Y`SYS";          /* y function name */
char  ZNAME[] =         "Z`SYS";          /* z function name */

char  VNAME[] =   "valid";          /* valid vertex name */

#define  ABS(x)         ((x)>=0 ? (x) : -(x))

#define  ZEROVECT(v)    (DOT(v,v) <= FTINY*FTINY)

#define  pvect(p) printf(vformat, (p)[0], (p)[1], (p)[2])

char  vformat[] = "%18.12g %18.12g %18.12g\n";
char  tsargs[] = "4 surf_dx surf_dy surf_dz surf.cal\n";
char  texname[] = "Phong";

int  smooth = 0;        /* apply smoothing? */
int  objout = 0;        /* output .OBJ format? */

char  *modname, *surfname;

                        /* recorded data flags */
#define  HASBORDER      01
#define  TRIPLETS 02
                        /* a data structure */
struct {
      int   flags;                  /* data type */
      short m, n;             /* number of s and t values */
      RREAL *data;                  /* the data itself, s major sort */
} datarec;              /* our recorded data */

/* XXX this is redundant with rt/noise3.c, should go to a library */
double  l_hermite(), l_bezier(), l_bspline(), l_dataval();

typedef struct {
      int  valid; /* point is valid (vertex number) */
      FVECT  p;   /* vertex position */
      FVECT  n;   /* average normal */
      RREAL  uv[2];     /* (u,v) position */
} POINT;


void loaddata(char *file, int m, int n, int pointsize);
double l_dataval(char *nam);
void putobjrow(POINT *rp, int n);
void putsquare(POINT *p0, POINT *p1, POINT *p2, POINT *p3);
void comprow(double s, POINT *row, int siz);
void compnorms(POINT *r0, POINT *r1, POINT *r2, int siz);
int norminterp(FVECT resmat[4], POINT *p0, POINT *p1, POINT *p2, POINT *p3);


int
main(argc, argv)
int  argc;
char  *argv[];
{
      POINT  *row0, *row1, *row2, *rp;
      int  i, j, m, n;
      char  stmp[256];

      varset("PI", ':', PI);
      funset("hermite", 5, ':', l_hermite);
      funset("bezier", 5, ':', l_bezier);
      funset("bspline", 5, ':', l_bspline);

      if (argc < 8)
            goto userror;

      for (i = 8; i < argc; i++)
            if (!strcmp(argv[i], "-e"))
                  scompile(argv[++i], NULL, 0);
            else if (!strcmp(argv[i], "-f"))
                  fcompile(argv[++i]);
            else if (!strcmp(argv[i], "-s"))
                  smooth++;
            else if (!strcmp(argv[i], "-o"))
                  objout++;
            else
                  goto userror;

      modname = argv[1];
      surfname = argv[2];
      m = atoi(argv[6]);
      n = atoi(argv[7]);
      if (m <= 0 || n <= 0)
            goto userror;
      if (!strcmp(argv[5], "-") || access(argv[5], 4) == 0) {     /* file? */
            funset(ZNAME, 2, ':', l_dataval);
            if (!strcmp(argv[5],argv[3]) && !strcmp(argv[5],argv[4])) {
                  loaddata(argv[5], m, n, 3);
                  funset(XNAME, 2, ':', l_dataval);
                  funset(YNAME, 2, ':', l_dataval);
            } else {
                  loaddata(argv[5], m, n, 1);
                  sprintf(stmp, "%s(s,t)=%s;", XNAME, argv[3]);
                  scompile(stmp, NULL, 0);
                  sprintf(stmp, "%s(s,t)=%s;", YNAME, argv[4]);
                  scompile(stmp, NULL, 0);
            }
      } else {
            sprintf(stmp, "%s(s,t)=%s;", XNAME, argv[3]);
            scompile(stmp, NULL, 0);
            sprintf(stmp, "%s(s,t)=%s;", YNAME, argv[4]);
            scompile(stmp, NULL, 0);
            sprintf(stmp, "%s(s,t)=%s;", ZNAME, argv[5]);
            scompile(stmp, NULL, 0);
      }
      row0 = (POINT *)malloc((n+3)*sizeof(POINT));
      row1 = (POINT *)malloc((n+3)*sizeof(POINT));
      row2 = (POINT *)malloc((n+3)*sizeof(POINT));
      if (row0 == NULL || row1 == NULL || row2 == NULL) {
            fprintf(stderr, "%s: out of memory\n", argv[0]);
            quit(1);
      }
      row0++; row1++; row2++;
                                    /* print header */
      fputs("# ", stdout);
      printargs(argc, argv, stdout);
      eclock = 0;
                                    /* initialize */
      comprow(-1.0/m, row0, n);
      comprow(0.0, row1, n);
      comprow(1.0/m, row2, n);
      compnorms(row0, row1, row2, n);
      if (objout) {
            printf("\nusemtl %s\n\n", modname);
            putobjrow(row1, n);
      }
                                    /* for each row */
      for (i = 0; i < m; i++) {
                                    /* compute next row */
            rp = row0;
            row0 = row1;
            row1 = row2;
            row2 = rp;
            comprow((double)(i+2)/m, row2, n);
            compnorms(row0, row1, row2, n);
            if (objout)
                  putobjrow(row1, n);

            for (j = 0; j < n; j++) {
                  int  orient = (j & 1);
                                          /* put polygons */
                  if (!(row0[j].valid && row1[j+1].valid))
                        orient = 1;
                  else if (!(row1[j].valid && row0[j+1].valid))
                        orient = 0;
                  if (orient)
                        putsquare(&row0[j], &row1[j],
                                    &row0[j+1], &row1[j+1]);
                  else
                        putsquare(&row1[j], &row1[j+1],
                                    &row0[j], &row0[j+1]);
            }
      }

      return 0;

userror:
      fprintf(stderr, "Usage: %s material name ", argv[0]);
      fprintf(stderr, "x(s,t) y(s,t) z(s,t) m n [-s][-o][-e expr][-f file]\n");
      return 1;
}


void
loaddata(         /* load point data from file */
      char  *file,
      int  m,
      int  n,
      int  pointsize
)
{
      FILE  *fp;
      char  word[64];
      register int  size;
      register RREAL  *dp;

      datarec.flags = HASBORDER;          /* assume border values */
      datarec.m = m+1;
      datarec.n = n+1;
      size = datarec.m*datarec.n*pointsize;
      if (pointsize == 3)
            datarec.flags |= TRIPLETS;
      dp = (RREAL *)malloc(size*sizeof(RREAL));
      if ((datarec.data = dp) == NULL) {
            fputs("Out of memory\n", stderr);
            exit(1);
      }
      if (!strcmp(file, "-")) {
            file = "<stdin>";
            fp = stdin;
      } else if ((fp = fopen(file, "r")) == NULL) {
            fputs(file, stderr);
            fputs(": cannot open\n", stderr);
            exit(1);
      }
      while (size > 0 && fgetword(word, sizeof(word), fp) != NULL) {
            if (!isflt(word)) {
                  fprintf(stderr, "%s: garbled data value: %s\n",
                              file, word);
                  exit(1);
            }
            *dp++ = atof(word);
            size--;
      }
      if (size == (m+n+1)*pointsize) {    /* no border after all */
            dp = (RREAL *)realloc((void *)datarec.data,
                        m*n*pointsize*sizeof(RREAL));
            if (dp != NULL)
                  datarec.data = dp;
            datarec.flags &= ~HASBORDER;
            datarec.m = m;
            datarec.n = n;
            size = 0;
      }
      if (datarec.m < 2 || datarec.n < 2 || size != 0 ||
                  fgetword(word, sizeof(word), fp) != NULL) {
            fputs(file, stderr);
            fputs(": bad number of data points\n", stderr);
            exit(1);
      }
      fclose(fp);
}


double
l_dataval(                    /* return recorded data value */
      char  *nam
)
{
      double  u, v;
      register int  i, j;
      register RREAL  *dp;
      double  d00, d01, d10, d11;
                                    /* compute coordinates */
      u = argument(1); v = argument(2);
      if (datarec.flags & HASBORDER) {
            i = u *= datarec.m-1;
            j = v *= datarec.n-1;
      } else {
            i = u = u*datarec.m - .5;
            j = v = v*datarec.n - .5;
      }
      if (i < 0) i = 0;
      else if (i > datarec.m-2) i = datarec.m-2;
      if (j < 0) j = 0;
      else if (j > datarec.n-2) j = datarec.n-2;
                                    /* compute value */
      if (datarec.flags & TRIPLETS) {
            dp = datarec.data + 3*(j*datarec.m + i);
            if (nam == ZNAME)
                  dp += 2;
            else if (nam == YNAME)
                  dp++;
            d00 = dp[0]; d01 = dp[3];
            dp += 3*datarec.m;
            d10 = dp[0]; d11 = dp[3];
      } else {
            dp = datarec.data + j*datarec.m + i;
            d00 = dp[0]; d01 = dp[1];
            dp += datarec.m;
            d10 = dp[0]; d11 = dp[1];
      }
                                    /* bilinear interpolation */
      return((j+1-v)*((i+1-u)*d00+(u-i)*d01)+(v-j)*((i+1-u)*d10+(u-i)*d11));
}


void
putobjrow(              /* output vertex row to .OBJ */
      register POINT  *rp,
      int  n
)
{
      static int  nverts = 0;

      for ( ; n-- >= 0; rp++) {
            if (!rp->valid)
                  continue;
            fputs("v ", stdout);
            pvect(rp->p);
            if (smooth && !ZEROVECT(rp->n))
                  printf("\tvn %.9g %.9g %.9g\n",
                              rp->n[0], rp->n[1], rp->n[2]);
            printf("\tvt %.9g %.9g\n", rp->uv[0], rp->uv[1]);
            rp->valid = ++nverts;
      }
}


void
putsquare(        /* put out a square */
      POINT *p0,
      POINT *p1,
      POINT *p2,
      POINT *p3
)
{
      static int  nout = 0;
      FVECT  norm[4];
      int  axis;
      FVECT  v1, v2, vc1, vc2;
      int  ok1, ok2;
                              /* compute exact normals */
      ok1 = (p0->valid && p1->valid && p2->valid);
      if (ok1) {
            VSUB(v1, p1->p, p0->p);
            VSUB(v2, p2->p, p0->p);
            fcross(vc1, v1, v2);
            ok1 = (normalize(vc1) != 0.0);
      }
      ok2 = (p1->valid && p2->valid && p3->valid);
      if (ok2) {
            VSUB(v1, p2->p, p3->p);
            VSUB(v2, p1->p, p3->p);
            fcross(vc2, v1, v2);
            ok2 = (normalize(vc2) != 0.0);
      }
      if (!(ok1 | ok2))
            return;
      if (objout) {                 /* output .OBJ faces */
            int   p0n=0, p1n=0, p2n=0, p3n=0;
            if (smooth) {
                  if (!ZEROVECT(p0->n))
                        p0n = p0->valid;
                  if (!ZEROVECT(p1->n))
                        p1n = p1->valid;
                  if (!ZEROVECT(p2->n))
                        p2n = p2->valid;
                  if (!ZEROVECT(p3->n))
                        p3n = p3->valid;
            }
            if (ok1 & ok2 && fdot(vc1,vc2) >= 1.0-FTINY*FTINY) {
                  printf("f %d/%d/%d %d/%d/%d %d/%d/%d %d/%d/%d\n",
                              p0->valid, p0->valid, p0n,
                              p1->valid, p1->valid, p1n,
                              p3->valid, p3->valid, p3n,
                              p2->valid, p2->valid, p2n);
                  return;
            }
            if (ok1)
                  printf("f %d/%d/%d %d/%d/%d %d/%d/%d\n",
                              p0->valid, p0->valid, p0n,
                              p1->valid, p1->valid, p1n,
                              p2->valid, p2->valid, p2n);
            if (ok2)
                  printf("f %d/%d/%d %d/%d/%d %d/%d/%d\n",
                              p2->valid, p2->valid, p2n,
                              p1->valid, p1->valid, p1n,
                              p3->valid, p3->valid, p3n);
            return;
      }
                              /* compute normal interpolation */
      axis = norminterp(norm, p0, p1, p2, p3);

                              /* put out quadrilateral? */
      if (ok1 & ok2 && fdot(vc1,vc2) >= 1.0-FTINY*FTINY) {
            printf("\n%s ", modname);
            if (axis != -1) {
                  printf("texfunc %s\n", texname);
                  printf(tsargs);
                  printf("0\n13\t%d\n", axis);
                  pvect(norm[0]);
                  pvect(norm[1]);
                  pvect(norm[2]);
                  fvsum(v1, norm[3], vc1, -0.5);
                  fvsum(v1, v1, vc2, -0.5);
                  pvect(v1);
                  printf("\n%s ", texname);
            }
            printf("polygon %s.%d\n", surfname, ++nout);
            printf("0\n0\n12\n");
            pvect(p0->p);
            pvect(p1->p);
            pvect(p3->p);
            pvect(p2->p);
            return;
      }
                              /* put out triangles? */
      if (ok1) {
            printf("\n%s ", modname);
            if (axis != -1) {
                  printf("texfunc %s\n", texname);
                  printf(tsargs);
                  printf("0\n13\t%d\n", axis);
                  pvect(norm[0]);
                  pvect(norm[1]);
                  pvect(norm[2]);
                  fvsum(v1, norm[3], vc1, -1.0);
                  pvect(v1);
                  printf("\n%s ", texname);
            }
            printf("polygon %s.%d\n", surfname, ++nout);
            printf("0\n0\n9\n");
            pvect(p0->p);
            pvect(p1->p);
            pvect(p2->p);
      }
      if (ok2) {
            printf("\n%s ", modname);
            if (axis != -1) {
                  printf("texfunc %s\n", texname);
                  printf(tsargs);
                  printf("0\n13\t%d\n", axis);
                  pvect(norm[0]);
                  pvect(norm[1]);
                  pvect(norm[2]);
                  fvsum(v2, norm[3], vc2, -1.0);
                  pvect(v2);
                  printf("\n%s ", texname);
            }
            printf("polygon %s.%d\n", surfname, ++nout);
            printf("0\n0\n9\n");
            pvect(p2->p);
            pvect(p1->p);
            pvect(p3->p);
      }
}


void
comprow(                /* compute row of values */
      double  s,
      register POINT  *row,
      int  siz
)
{
      double  st[2];
      int  end;
      int  checkvalid;
      register int  i;
      
      if (smooth) {
            i = -1;                 /* compute one past each end */
            end = siz+1;
      } else {
            if (s < -FTINY || s > 1.0+FTINY)
                  return;
            i = 0;
            end = siz;
      }
      st[0] = s;
      checkvalid = (fundefined(VNAME) == 2);
      while (i <= end) {
            st[1] = (double)i/siz;
            if (checkvalid && funvalue(VNAME, 2, st) <= 0.0) {
                  row[i].valid = 0;
                  row[i].p[0] = row[i].p[1] = row[i].p[2] = 0.0;
                  row[i].uv[0] = row[i].uv[1] = 0.0;
            } else {
                  row[i].valid = 1;
                  row[i].p[0] = funvalue(XNAME, 2, st);
                  row[i].p[1] = funvalue(YNAME, 2, st);
                  row[i].p[2] = funvalue(ZNAME, 2, st);
                  row[i].uv[0] = st[0];
                  row[i].uv[1] = st[1];
            }
            i++;
      }
}


void
compnorms(        /* compute row of averaged normals */
      register POINT  *r0,
      register POINT  *r1,
      register POINT  *r2,
      int  siz
)
{
      FVECT  v1, v2;

      if (!smooth)                  /* not needed if no smoothing */
            return;
                              /* compute row 1 normals */
      while (siz-- >= 0) {
            if (!r1[0].valid)
                  continue;
            if (!r0[0].valid) {
                  if (!r2[0].valid) {
                        r1[0].n[0] = r1[0].n[1] = r1[0].n[2] = 0.0;
                        continue;
                  }
                  fvsum(v1, r2[0].p, r1[0].p, -1.0);
            } else if (!r2[0].valid)
                  fvsum(v1, r1[0].p, r0[0].p, -1.0);
            else
                  fvsum(v1, r2[0].p, r0[0].p, -1.0);
            if (!r1[-1].valid) {
                  if (!r1[1].valid) {
                        r1[0].n[0] = r1[0].n[1] = r1[0].n[2] = 0.0;
                        continue;
                  }
                  fvsum(v2, r1[1].p, r1[0].p, -1.0);
            } else if (!r1[1].valid)
                  fvsum(v2, r1[0].p, r1[-1].p, -1.0);
            else
                  fvsum(v2, r1[1].p, r1[-1].p, -1.0);
            fcross(r1[0].n, v1, v2);
            normalize(r1[0].n);
            r0++; r1++; r2++;
      }
}


int
norminterp( /* compute normal interpolation */
      register FVECT  resmat[4],
      POINT  *p0,
      POINT  *p1,
      POINT  *p2,
      POINT  *p3
)
{
#define u  ((ax+1)%3)
#define v  ((ax+2)%3)

      register int  ax;
      MAT4  eqnmat;
      FVECT  v1;
      register int  i, j;

      if (!smooth)                  /* no interpolation if no smoothing */
            return(-1);
                              /* find dominant axis */
      VCOPY(v1, p0->n);
      fvsum(v1, v1, p1->n, 1.0);
      fvsum(v1, v1, p2->n, 1.0);
      fvsum(v1, v1, p3->n, 1.0);
      ax = ABS(v1[0]) > ABS(v1[1]) ? 0 : 1;
      ax = ABS(v1[ax]) > ABS(v1[2]) ? ax : 2;
                              /* assign equation matrix */
      eqnmat[0][0] = p0->p[u]*p0->p[v];
      eqnmat[0][1] = p0->p[u];
      eqnmat[0][2] = p0->p[v];
      eqnmat[0][3] = 1.0;
      eqnmat[1][0] = p1->p[u]*p1->p[v];
      eqnmat[1][1] = p1->p[u];
      eqnmat[1][2] = p1->p[v];
      eqnmat[1][3] = 1.0;
      eqnmat[2][0] = p2->p[u]*p2->p[v];
      eqnmat[2][1] = p2->p[u];
      eqnmat[2][2] = p2->p[v];
      eqnmat[2][3] = 1.0;
      eqnmat[3][0] = p3->p[u]*p3->p[v];
      eqnmat[3][1] = p3->p[u];
      eqnmat[3][2] = p3->p[v];
      eqnmat[3][3] = 1.0;
                              /* invert matrix (solve system) */
      if (!invmat4(eqnmat, eqnmat))
            return(-1);             /* no solution */
                              /* compute result matrix */
      for (j = 0; j < 4; j++)
            for (i = 0; i < 3; i++)
                  resmat[j][i] =    eqnmat[j][0]*p0->n[i] +
                              eqnmat[j][1]*p1->n[i] +
                              eqnmat[j][2]*p2->n[i] +
                              eqnmat[j][3]*p3->n[i];
      return(ax);

#undef u
#undef v
}


double
l_hermite(char *nm)
{
      double  t;
      
      t = argument(5);
      return(     argument(1)*((2.0*t-3.0)*t*t+1.0) +
            argument(2)*(-2.0*t+3.0)*t*t +
            argument(3)*((t-2.0)*t+1.0)*t +
            argument(4)*(t-1.0)*t*t );
}


double
l_bezier(char *nm)
{
      double  t;

      t = argument(5);
      return(     argument(1) * (1.+t*(-3.+t*(3.-t))) +
            argument(2) * 3.*t*(1.+t*(-2.+t)) +
            argument(3) * 3.*t*t*(1.-t) +
            argument(4) * t*t*t );
}


double
l_bspline(char *nm)
{
      double  t;

      t = argument(5);
      return(     argument(1) * (1./6.+t*(-1./2.+t*(1./2.-1./6.*t))) +
            argument(2) * (2./3.+t*t*(-1.+1./2.*t)) +
            argument(3) * (1./6.+t*(1./2.+t*(1./2.-1./2.*t))) +
            argument(4) * (1./6.*t*t*t) );
}

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