| 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 |
|
|
