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greg |
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/* |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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* gensurf.c - program to generate functional surfaces |
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* |
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* Parametric functions x(s,t), y(s,t) and z(s,t) |
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* specify the surface, which is tesselated into an m by n |
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* array of paired triangles. |
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* The surface normal is defined by the right hand |
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* rule applied to (s,t). |
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* |
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* 4/3/87 |
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*/ |
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#include <stdio.h> |
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#define XNAME "X_" /* x function name */ |
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#define YNAME "Y_" /* y function name */ |
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#define ZNAME "Z_" /* z function name */ |
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#define PI 3.14159265358979323846 |
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#define FTINY 1e-7 |
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#define vertex(p) printf(vformat, (p)[0], (p)[1], (p)[2]) |
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char vformat[] = "%15.9g %15.9g %15.9g\n"; |
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double funvalue(), dist2(), fdot(), l_hermite(), argument(); |
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main(argc, argv) |
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int argc; |
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char *argv[]; |
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{ |
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static double *xyz[4]; |
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double *row0, *row1, *dp; |
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double v1[3], v2[3], vc1[3], vc2[3]; |
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double a1, a2; |
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int i, j, m, n; |
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char stmp[256]; |
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double d; |
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register int k; |
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varset("PI", PI); |
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funset("hermite", 5, l_hermite); |
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if (argc < 8) |
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goto userror; |
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for (i = 8; i < argc; i++) |
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if (!strcmp(argv[i], "-e")) |
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scompile(NULL, argv[++i]); |
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else if (!strcmp(argv[i], "-f")) |
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fcompile(argv[++i]); |
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else |
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goto userror; |
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sprintf(stmp, "%s(s,t)=%s;", XNAME, argv[3]); |
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scompile(NULL, stmp); |
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sprintf(stmp, "%s(s,t)=%s;", YNAME, argv[4]); |
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scompile(NULL, stmp); |
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sprintf(stmp, "%s(s,t)=%s;", ZNAME, argv[5]); |
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scompile(NULL, stmp); |
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m = atoi(argv[6]); |
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n = atoi(argv[7]); |
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if (m <= 0 || n <= 0) |
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goto userror; |
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row0 = (double *)malloc((n+1)*3*sizeof(double)); |
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row1 = (double *)malloc((n+1)*3*sizeof(double)); |
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if (row0 == NULL || row1 == NULL) { |
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fprintf(stderr, "%s: out of memory\n", argv[0]); |
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quit(1); |
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} |
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printhead(argc, argv); |
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comprow(0.0, row1, n); /* compute zeroeth row */ |
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for (i = 0; i < m; i++) { |
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/* compute next row */ |
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dp = row0; |
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row0 = row1; |
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row1 = dp; |
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comprow((double)(i+1)/m, row1, n); |
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for (j = 0; j < n; j++) { |
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/* get vertices */ |
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xyz[0] = row0 + 3*j; |
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xyz[1] = row1 + 3*j; |
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xyz[2] = xyz[0] + 3; |
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xyz[3] = xyz[1] + 3; |
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/* rotate vertices */ |
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if (dist2(xyz[0],xyz[3]) < dist2(xyz[1],xyz[2])-FTINY) { |
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dp = xyz[0]; |
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xyz[0] = xyz[1]; |
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xyz[1] = xyz[3]; |
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xyz[3] = xyz[2]; |
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xyz[2] = dp; |
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} |
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/* get normals */ |
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for (k = 0; k < 3; k++) { |
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v1[k] = xyz[1][k] - xyz[0][k]; |
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v2[k] = xyz[2][k] - xyz[0][k]; |
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} |
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fcross(vc1, v1, v2); |
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a1 = fdot(vc1, vc1); |
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for (k = 0; k < 3; k++) { |
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v1[k] = xyz[2][k] - xyz[3][k]; |
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v2[k] = xyz[1][k] - xyz[3][k]; |
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} |
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fcross(vc2, v1, v2); |
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a2 = fdot(vc2, vc2); |
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/* check coplanar */ |
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if (a1 > FTINY*FTINY && a2 > FTINY*FTINY) { |
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d = fdot(vc1, vc2); |
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if (d*d/a1/a2 >= 1.0-FTINY*FTINY) { |
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if (d > 0.0) { /* coplanar */ |
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printf( |
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"\n%s polygon %s.%d.%d\n", |
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argv[1], argv[2], i+1, j+1); |
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printf("0\n0\n12\n"); |
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vertex(xyz[0]); |
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vertex(xyz[1]); |
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vertex(xyz[3]); |
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vertex(xyz[2]); |
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} /* else overlapped */ |
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continue; |
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} /* else bent */ |
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} |
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/* check triangles */ |
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if (a1 > FTINY*FTINY) { |
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printf("\n%s polygon %s.%da%d\n", |
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argv[1], argv[2], i+1, j+1); |
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printf("0\n0\n9\n"); |
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vertex(xyz[0]); |
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vertex(xyz[1]); |
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vertex(xyz[2]); |
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} |
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if (a2 > FTINY*FTINY) { |
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printf("\n%s polygon %s.%db%d\n", |
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argv[1], argv[2], i+1, j+1); |
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printf("0\n0\n9\n"); |
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vertex(xyz[2]); |
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vertex(xyz[1]); |
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vertex(xyz[3]); |
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} |
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} |
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} |
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quit(0); |
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userror: |
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fprintf(stderr, "Usage: %s material name ", argv[0]); |
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fprintf(stderr, "x(s,t) y(s,t) z(s,t) m n [-e expr] [-f file]\n"); |
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quit(1); |
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} |
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comprow(s, row, siz) /* compute row of values */ |
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double s; |
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register double *row; |
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int siz; |
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{ |
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double st[2], step; |
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st[0] = s; |
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st[1] = 0.0; |
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step = 1.0 / siz; |
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while (siz-- >= 0) { |
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*row++ = funvalue(XNAME, 2, st); |
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*row++ = funvalue(YNAME, 2, st); |
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*row++ = funvalue(ZNAME, 2, st); |
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st[1] += step; |
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} |
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} |
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eputs(msg) |
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char *msg; |
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{ |
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fputs(msg, stderr); |
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} |
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wputs(msg) |
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char *msg; |
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{ |
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eputs(msg); |
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} |
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quit(code) |
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{ |
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exit(code); |
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} |
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printhead(ac, av) /* print command header */ |
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register int ac; |
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register char **av; |
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{ |
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putchar('#'); |
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while (ac--) { |
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putchar(' '); |
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fputs(*av++, stdout); |
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} |
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putchar('\n'); |
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} |
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double |
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l_hermite() |
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{ |
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double t; |
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t = argument(5); |
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return( argument(1)*((2.0*t-3.0)*t*t+1.0) + |
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argument(2)*(-2.0*t+3.0)*t*t + |
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argument(3)*((t-2.0)*t+1.0)*t + |
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argument(4)*(t-1.0)*t*t ); |
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} |
