Revision: 41013
http://brlcad.svn.sourceforge.net/brlcad/?rev=41013&view=rev
Author: r_weiss
Date: 2010-10-16 02:49:48 +0000 (Sat, 16 Oct 2010)
Log Message:
-----------
In function bn_isect_line3_line3, made many changes to tolerances and added
checks for zero magnitude vectors. Made a logic change to improve detecting
colinear lines. This function needs more work but I believe it is working
better.
Modified Paths:
--------------
brlcad/trunk/src/libbn/plane.c
Modified: brlcad/trunk/src/libbn/plane.c
===================================================================
--- brlcad/trunk/src/libbn/plane.c 2010-10-15 22:13:52 UTC (rev 41012)
+++ brlcad/trunk/src/libbn/plane.c 2010-10-16 02:49:48 UTC (rev 41013)
@@ -1222,9 +1222,16 @@
register fastf_t det;
register fastf_t det1;
register short int q, r, s;
+ int parallel = 0;
+ int colinear = 0;
+
BN_CK_TOL(tol);
+ if (NEAR_ZERO(MAGSQ(c), VUNITIZE_TOL) || NEAR_ZERO(MAGSQ(d),
VUNITIZE_TOL)) {
+ bu_bomb("bn_isect_line3_line3(): input vector(s) 'c' and/or 'd' is
zero magnitude.\n");
+ }
+
/* Any intersection will occur in the plane with surface normal D
* cross C, which may not have unit length. The plane containing
* the two lines will be a constant distance from a plane with the
@@ -1234,26 +1241,33 @@
* no intersection, because P and A must lie on parallel planes
* that are different distances from the origin.
*/
+
VCROSS(n, d, c);
det = VDOT(n, p) - VDOT(n, a);
- if (!NEAR_ZERO(det, tol->dist)) {
- return -1; /* No intersection */
+ if (!NEAR_ZERO(det, SMALL_FASTF)) {
+ return -1; /* no intersection, lines not in same plane */
}
- if (NEAR_ZERO(MAGSQ(n), SMALL_FASTF))
- {
+ if (NEAR_ZERO(MAGSQ(n), VUNITIZE_TOL)) {
+ /* lines are parallel, must find another way to get normal vector */
vect_t a_to_p;
- /* lines are parallel, must find another way to get normal
- * vector.
- */
+ parallel = 1;
VSUB2(a_to_p, p, a);
VCROSS(n, a_to_p, d);
- if (NEAR_ZERO(MAGSQ(n), SMALL_FASTF))
+ if (NEAR_ZERO(MAGSQ(n), VUNITIZE_TOL)) {
+ /* lines are parallel and colinear */
+
+ colinear = 1;
bn_vec_ortho(n, d);
+ }
}
+ if (NEAR_ZERO(MAGSQ(n), VUNITIZE_TOL)) {
+ bu_bomb("bn_isect_line3_line3(): ortho vector zero magnitude\n");
+ }
+
/* Solve for t and u in the system:
*
* Px + t * Dx = Ax + u * Cx
@@ -1274,9 +1288,19 @@
* than x, y, z. Subscript s is the smallest component, used for
* checking later.
*/
+ if (NEAR_ZERO(n[X], SMALL_FASTF)) {
+ n[X] = 0.0;
+ }
+ if (NEAR_ZERO(n[Y], SMALL_FASTF)) {
+ n[Y] = 0.0;
+ }
+ if (NEAR_ZERO(n[Z], SMALL_FASTF)) {
+ n[Z] = 0.0;
+ }
abs_n[X] = (n[X] >= 0) ? n[X] : (-n[X]);
abs_n[Y] = (n[Y] >= 0) ? n[Y] : (-n[Y]);
abs_n[Z] = (n[Z] >= 0) ? n[Z] : (-n[Z]);
+
if (abs_n[X] >= abs_n[Y]) {
if (abs_n[X] >= abs_n[Z]) {
/* X is largest in magnitude */
@@ -1342,9 +1366,8 @@
*/
if (NEAR_ZERO(det, DETERMINANT_TOL)) {
/* Lines are parallel */
- if (!NEAR_ZERO(det1, DETERMINANT_TOL)) {
- /* Lines are NOT co-linear, just parallel */
- return -2; /* parallel, no intersection */
+ if (!colinear || !NEAR_ZERO(det1, DETERMINANT_TOL)) {
+ return -2; /* parallel, not colinear, no intersection */
}
/* Lines are co-linear */
@@ -1392,7 +1415,7 @@
* distance.
*/
det = *t * d[s] - *u * c[s] - h[s];
- if (!NEAR_ZERO(det, tol->dist)) {
+ if (!NEAR_ZERO(det, SMALL_FASTF)) {
/* XXX This tolerance needs to be much less loose than
* SQRT_SMALL_FASTF. What about DETERMINANT_TOL?
*/
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