429 |
|
eqnmat[3][2] = p3->p[v]; |
430 |
|
eqnmat[3][3] = 1.0; |
431 |
|
/* invert matrix (solve system) */ |
432 |
< |
if (!invmat(eqnmat, eqnmat)) |
432 |
> |
if (!invmat4(eqnmat, eqnmat)) |
433 |
|
return(-1); /* no solution */ |
434 |
|
/* compute result matrix */ |
435 |
|
for (j = 0; j < 4; j++) |
442 |
|
|
443 |
|
#undef u |
444 |
|
#undef v |
445 |
– |
} |
446 |
– |
|
447 |
– |
|
448 |
– |
/* |
449 |
– |
* invmat - computes the inverse of mat into inverse. Returns 1 |
450 |
– |
* if there exists an inverse, 0 otherwise. It uses Gaussian Elimination |
451 |
– |
* method. |
452 |
– |
*/ |
453 |
– |
|
454 |
– |
invmat(inverse,mat) |
455 |
– |
MAT4 inverse, mat; |
456 |
– |
{ |
457 |
– |
#define SWAP(a,b,t) (t=a,a=b,b=t) |
458 |
– |
|
459 |
– |
MAT4 m4tmp; |
460 |
– |
register int i,j,k; |
461 |
– |
register double temp; |
462 |
– |
|
463 |
– |
copymat4(m4tmp, mat); |
464 |
– |
/* set inverse to identity */ |
465 |
– |
for (i = 0; i < 4; i++) |
466 |
– |
for (j = 0; j < 4; j++) |
467 |
– |
inverse[i][j] = i==j ? 1.0 : 0.0; |
468 |
– |
|
469 |
– |
for(i = 0; i < 4; i++) { |
470 |
– |
/* Look for row with largest pivot and swap rows */ |
471 |
– |
temp = FTINY; j = -1; |
472 |
– |
for(k = i; k < 4; k++) |
473 |
– |
if(ABS(m4tmp[k][i]) > temp) { |
474 |
– |
temp = ABS(m4tmp[k][i]); |
475 |
– |
j = k; |
476 |
– |
} |
477 |
– |
if(j == -1) /* No replacing row -> no inverse */ |
478 |
– |
return(0); |
479 |
– |
if (j != i) |
480 |
– |
for(k = 0; k < 4; k++) { |
481 |
– |
SWAP(m4tmp[i][k],m4tmp[j][k],temp); |
482 |
– |
SWAP(inverse[i][k],inverse[j][k],temp); |
483 |
– |
} |
484 |
– |
|
485 |
– |
temp = m4tmp[i][i]; |
486 |
– |
for(k = 0; k < 4; k++) { |
487 |
– |
m4tmp[i][k] /= temp; |
488 |
– |
inverse[i][k] /= temp; |
489 |
– |
} |
490 |
– |
for(j = 0; j < 4; j++) { |
491 |
– |
if(j != i) { |
492 |
– |
temp = m4tmp[j][i]; |
493 |
– |
for(k = 0; k < 4; k++) { |
494 |
– |
m4tmp[j][k] -= m4tmp[i][k]*temp; |
495 |
– |
inverse[j][k] -= inverse[i][k]*temp; |
496 |
– |
} |
497 |
– |
} |
498 |
– |
} |
499 |
– |
} |
500 |
– |
return(1); |
501 |
– |
|
502 |
– |
#undef SWAP |
445 |
|
} |
446 |
|
|
447 |
|
|