Revision: 45531
http://brlcad.svn.sourceforge.net/brlcad/?rev=45531&view=rev
Author: r_weiss
Date: 2011-07-18 21:23:26 +0000 (Mon, 18 Jul 2011)
Log Message:
-----------
Created a new prototype version of function bn_isect_line_lseg in the libbn
library within file plane.c. This new version is disabled by default and exists
to support the prototype version of nmg_triangulate_fu. The changes to this
function were necessary to process the output from the prototype function
bn_isect_line3_line3_new. This is a work in progress.
Modified Paths:
--------------
brlcad/trunk/src/libbn/plane.c
Modified: brlcad/trunk/src/libbn/plane.c
===================================================================
--- brlcad/trunk/src/libbn/plane.c 2011-07-18 20:55:33 UTC (rev 45530)
+++ brlcad/trunk/src/libbn/plane.c 2011-07-18 21:23:26 UTC (rev 45531)
@@ -1933,6 +1933,129 @@
int
bn_isect_line_lseg(fastf_t *t, const fastf_t *p, const fastf_t *d, const
fastf_t *a, const fastf_t *b, const struct bn_tol *tol)
{
+#ifdef TRI_PROTOTYPE
+ vect_t ab, pa, pb; /* direction vectors a->b, p->a, p->b */
+ auto fastf_t u; /* As in, A + u * C = X */
+ register int ret;
+
+ fastf_t ab_mag;
+ fastf_t pa_mag_sq;
+ fastf_t pb_mag_sq;
+ fastf_t d_mag_sq;
+
+ BN_CK_TOL(tol);
+
+ d_mag_sq = MAGSQ(d);
+ if (ZERO(d_mag_sq)) {
+ bu_bomb("bn_isect_line_lseg(): ray direction vector zero magnitude\n");
+ }
+
+ VSUB2(ab, b, a);
+ ab_mag = MAGNITUDE(ab);
+ if (ab_mag < tol->dist) {
+ /* points A and B are not distinct */
+ return -4;
+ }
+
+ VSUB2(pa, a, p);
+ pa_mag_sq = MAGSQ(pa);
+ if (pa_mag_sq < tol->dist_sq) {
+ /* Intersection at vertex A */
+ *t = sqrt(pa_mag_sq);
+ return 1;
+ }
+
+ VSUB2(pb, b, p);
+ pb_mag_sq = MAGSQ(pb);
+ if (pb_mag_sq < tol->dist_sq) {
+ /* Intersection at vertex B */
+ *t = sqrt(pb_mag_sq);
+ return 2;
+ }
+
+ /* Detecting colinearity is difficult, and very very important.
+ * As a first step, check to see if both points A and B lie within
+ * tolerance of the line. If so, then the line segment AC is ON
+ * the line.
+ */
+ if (bn_distsq_line3_pt3(p, d, a) <= tol->dist_sq &&
+ bn_distsq_line3_pt3(p, d, b) <= tol->dist_sq) {
+ if (bu_debug & BU_DEBUG_MATH) {
+ bu_log("bn_isect_line3_lseg3() pts A and B within tol of line\n");
+ }
+ /* Find the parametric distance along the ray */
+ *t = bn_dist_pt3_along_line3(p, d, a);
+
+ if (*t < -tol->dist) {
+ /* intersection of ray and line segment but in the
+ * negative direction of the ray
+ */
+ return -1;
+ } else {
+ if (ZERO(*t)) {
+ *t = 0.0;
+ }
+ /* co-linear (t was computed for point A, u=0) */
+ return 0;
+ }
+ }
+
+ if ((ret = bn_isect_line3_line3_new(t, &u, p, d, a, ab, tol)) < 0) {
+ /* No intersection found */
+ return -1;
+ }
+
+ if (ret == 0) {
+ /* co-linear (t was computed for point A, u=0) */
+ return 0;
+ }
+
+ if (ZERO(*t)) {
+ *t = 0.0;
+ }
+
+ if (ZERO(u)) {
+ u = 0.0;
+ }
+
+ if (*t < -tol->dist) {
+ /* intersection of ray and line segment but in the
+ * negative direction of the ray
+ */
+ return -1;
+ }
+
+ if (NEAR_ZERO(u, tol->dist)) {
+ /* Intersection at vertex A */
+ /* use actual distance instead of hit point */
+ *t = sqrt(pa_mag_sq);
+ return 1;
+ }
+ if (u < -tol->dist) {
+ /* Intersection exists, < A (t is returned) */
+ return -3;
+ }
+
+ /* the computation (u - ab_mag) might cause some problems
+ * because 'u' can be negative but 'ab_mag' can not
+ */
+ if (NEAR_ZERO(u - ab_mag, tol->dist)) {
+ /* Intersection at vertex B */
+ /* use actual distance instead of hit point */
+ *t = sqrt(pb_mag_sq);
+ return 2;
+ }
+
+ if (u > ab_mag + tol->dist) {
+ /* Intersection exists, > B (t is returned) */
+ return -2;
+ }
+
+ /* Intersection between A and B */
+ return 3;
+
+#else
+
vect_t c; /* Direction vector from A to B */
auto fastf_t u; /* As in, A + u * C = X */
register fastf_t f;
@@ -1995,6 +2118,8 @@
return 2; /* Intersection at B */
return 3; /* Intersection between A and B */
+
+#endif
}
@@ -3308,8 +3433,3 @@
* ex: shiftwidth=4 tabstop=8
*/
-
-
-
-
-
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