--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/ode/src/collision_util.cpp Tue Feb 02 01:00:49 2010 +0200
@@ -0,0 +1,638 @@
+/*************************************************************************
+ * *
+ * Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith. *
+ * All rights reserved. Email: russ@q12.org Web: www.q12.org *
+ * *
+ * This library is free software; you can redistribute it and/or *
+ * modify it under the terms of EITHER: *
+ * (1) The GNU Lesser General Public License as published by the Free *
+ * Software Foundation; either version 2.1 of the License, or (at *
+ * your option) any later version. The text of the GNU Lesser *
+ * General Public License is included with this library in the *
+ * file LICENSE.TXT. *
+ * (2) The BSD-style license that is included with this library in *
+ * the file LICENSE-BSD.TXT. *
+ * *
+ * This library is distributed in the hope that it will be useful, *
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files *
+ * LICENSE.TXT and LICENSE-BSD.TXT for more details. *
+ * *
+ *************************************************************************/
+
+/*
+
+some useful collision utility stuff. this includes some API utility
+functions that are defined in the public header files.
+
+*/
+
+#include <ode/common.h>
+#include <ode/collision.h>
+#include <ode/odemath.h>
+#include "collision_util.h"
+
+//****************************************************************************
+
+int dCollideSpheres (dVector3 p1, dReal r1,
+ dVector3 p2, dReal r2, dContactGeom *c)
+{
+ // printf ("d=%.2f (%.2f %.2f %.2f) (%.2f %.2f %.2f) r1=%.2f r2=%.2f\n",
+ // d,p1[0],p1[1],p1[2],p2[0],p2[1],p2[2],r1,r2);
+
+ dReal d = dDISTANCE (p1,p2);
+ if (d > (r1 + r2)) return 0;
+ if (d <= 0) {
+ c->pos[0] = p1[0];
+ c->pos[1] = p1[1];
+ c->pos[2] = p1[2];
+ c->normal[0] = 1;
+ c->normal[1] = 0;
+ c->normal[2] = 0;
+ c->depth = r1 + r2;
+ }
+ else {
+ dReal d1 = dRecip (d);
+ c->normal[0] = dMUL((p1[0]-p2[0]),d1);
+ c->normal[1] = dMUL((p1[1]-p2[1]),d1);
+ c->normal[2] = dMUL((p1[2]-p2[2]),d1);
+ dReal k = dMUL(REAL(0.5),(r2 - r1 - d));
+ c->pos[0] = p1[0] + dMUL(c->normal[0],k);
+ c->pos[1] = p1[1] + dMUL(c->normal[1],k);
+ c->pos[2] = p1[2] + dMUL(c->normal[2],k);
+ c->depth = r1 + r2 - d;
+ }
+ return 1;
+}
+
+
+void dLineClosestApproach (const dVector3 pa, const dVector3 ua,
+ const dVector3 pb, const dVector3 ub,
+ dReal *alpha, dReal *beta)
+{
+ dVector3 p;
+ p[0] = pb[0] - pa[0];
+ p[1] = pb[1] - pa[1];
+ p[2] = pb[2] - pa[2];
+ dReal uaub = dDOT(ua,ub);
+ dReal q1 = dDOT(ua,p);
+ dReal q2 = -dDOT(ub,p);
+ dReal d = 1-dMUL(uaub,uaub);
+ if (d <= REAL(0.0001)) {
+ // @@@ this needs to be made more robust
+ *alpha = 0;
+ *beta = 0;
+ }
+ else {
+ d = dRecip(d);
+ *alpha = dMUL((q1 + dMUL(uaub,q2)),d);
+ *beta = dMUL((dMUL(uaub,q1) + q2),d);
+ }
+}
+
+
+// given two line segments A and B with endpoints a1-a2 and b1-b2, return the
+// points on A and B that are closest to each other (in cp1 and cp2).
+// in the case of parallel lines where there are multiple solutions, a
+// solution involving the endpoint of at least one line will be returned.
+// this will work correctly for zero length lines, e.g. if a1==a2 and/or
+// b1==b2.
+//
+// the algorithm works by applying the voronoi clipping rule to the features
+// of the line segments. the three features of each line segment are the two
+// endpoints and the line between them. the voronoi clipping rule states that,
+// for feature X on line A and feature Y on line B, the closest points PA and
+// PB between X and Y are globally the closest points if PA is in V(Y) and
+// PB is in V(X), where V(X) is the voronoi region of X.
+
+EXPORT_C void dClosestLineSegmentPoints (const dVector3 a1, const dVector3 a2,
+ const dVector3 b1, const dVector3 b2,
+ dVector3 cp1, dVector3 cp2)
+{
+ dVector3 a1a2,b1b2,a1b1,a1b2,a2b1,a2b2,n;
+ dReal la,lb,k,da1,da2,da3,da4,db1,db2,db3,db4,det;
+
+#define SET2(a,b) a[0]=b[0]; a[1]=b[1]; a[2]=b[2];
+#define SET3(a,b,op,c) a[0]=b[0] op c[0]; a[1]=b[1] op c[1]; a[2]=b[2] op c[2];
+
+ // check vertex-vertex features
+
+ SET3 (a1a2,a2,-,a1);
+ SET3 (b1b2,b2,-,b1);
+ SET3 (a1b1,b1,-,a1);
+ da1 = dDOT(a1a2,a1b1);
+ db1 = dDOT(b1b2,a1b1);
+ if (da1 <= 0 && db1 >= 0) {
+ SET2 (cp1,a1);
+ SET2 (cp2,b1);
+ return;
+ }
+
+ SET3 (a1b2,b2,-,a1);
+ da2 = dDOT(a1a2,a1b2);
+ db2 = dDOT(b1b2,a1b2);
+ if (da2 <= 0 && db2 <= 0) {
+ SET2 (cp1,a1);
+ SET2 (cp2,b2);
+ return;
+ }
+
+ SET3 (a2b1,b1,-,a2);
+ da3 = dDOT(a1a2,a2b1);
+ db3 = dDOT(b1b2,a2b1);
+ if (da3 >= 0 && db3 >= 0) {
+ SET2 (cp1,a2);
+ SET2 (cp2,b1);
+ return;
+ }
+
+ SET3 (a2b2,b2,-,a2);
+ da4 = dDOT(a1a2,a2b2);
+ db4 = dDOT(b1b2,a2b2);
+ if (da4 >= 0 && db4 <= 0) {
+ SET2 (cp1,a2);
+ SET2 (cp2,b2);
+ return;
+ }
+
+ // check edge-vertex features.
+ // if one or both of the lines has zero length, we will never get to here,
+ // so we do not have to worry about the following divisions by zero.
+
+ la = dDOT(a1a2,a1a2);
+ if (da1 >= 0 && da3 <= 0) {
+ k = dDIV(da1,la);
+ a1a2[0] = dMUL(k,a1a2[0]);
+ a1a2[1] = dMUL(k,a1a2[1]);
+ a1a2[2] = dMUL(k,a1a2[2]);
+ SET3 (n,a1b1,-,a1a2);
+ if (dDOT(b1b2,n) >= 0) {
+ a1a2[0] = dMUL(k,a1a2[0]);
+ a1a2[1] = dMUL(k,a1a2[1]);
+ a1a2[2] = dMUL(k,a1a2[2]);
+ SET3 (cp1,a1,+,a1a2);
+ SET2 (cp2,b1);
+ return;
+ }
+ }
+
+ if (da2 >= 0 && da4 <= 0) {
+ k = dDIV(da2,la);
+ a1a2[0] = dMUL(k,a1a2[0]);
+ a1a2[1] = dMUL(k,a1a2[1]);
+ a1a2[2] = dMUL(k,a1a2[2]);
+ SET3 (n,a1b2,-,a1a2);
+ if (dDOT(b1b2,n) <= 0) {
+ a1a2[0] = dMUL(k,a1a2[0]);
+ a1a2[1] = dMUL(k,a1a2[1]);
+ a1a2[2] = dMUL(k,a1a2[2]);
+ SET3 (cp1,a1,+,a1a2);
+ SET2 (cp2,b2);
+ return;
+ }
+ }
+
+ lb = dDOT(b1b2,b1b2);
+ if (db1 <= 0 && db2 >= 0) {
+ k = -dDIV(db1,lb);
+ b1b2[0] = dMUL(k,b1b2[0]);
+ b1b2[1] = dMUL(k,b1b2[1]);
+ b1b2[2] = dMUL(k,b1b2[2]);
+ SET3 (n,-a1b1,-,b1b2);
+ if (dDOT(a1a2,n) >= 0) {
+ b1b2[0] = dMUL(k,b1b2[0]);
+ b1b2[1] = dMUL(k,b1b2[1]);
+ b1b2[2] = dMUL(k,b1b2[2]);
+ SET2 (cp1,a1);
+ SET3 (cp2,b1,+,b1b2);
+ return;
+ }
+ }
+
+ if (db3 <= 0 && db4 >= 0) {
+ k = -dDIV(db3,lb);
+ b1b2[0] = dMUL(k,b1b2[0]);
+ b1b2[1] = dMUL(k,b1b2[1]);
+ b1b2[2] = dMUL(k,b1b2[2]);
+ SET3 (n,-a2b1,-,b1b2);
+ if (dDOT(a1a2,n) <= 0) {
+ b1b2[0] = dMUL(k,b1b2[0]);
+ b1b2[1] = dMUL(k,b1b2[1]);
+ b1b2[2] = dMUL(k,b1b2[2]);
+ SET2 (cp1,a2);
+ SET3 (cp2,b1,+,b1b2);
+ return;
+ }
+ }
+
+ // it must be edge-edge
+
+ k = dDOT(a1a2,b1b2);
+ det = dMUL(la,lb) - dMUL(k,k);
+ if (det <= 0) {
+ // this should never happen, but just in case...
+ SET2(cp1,a1);
+ SET2(cp2,b1);
+ return;
+ }
+ det = dRecip (det);
+ dReal alpha = dMUL((dMUL(lb,da1) - dMUL(k,db1)),det);
+ a1a2[0] = dMUL(alpha,a1a2[0]);
+ a1a2[1] = dMUL(alpha,a1a2[1]);
+ a1a2[2] = dMUL(alpha,a1a2[2]);
+ dReal beta = dMUL(( dMUL(k,da1) - dMUL(la,db1)),det);
+ b1b2[0] = dMUL(beta,b1b2[0]);
+ b1b2[1] = dMUL(beta,b1b2[1]);
+ b1b2[2] = dMUL(beta,b1b2[2]);
+ SET3 (cp1,a1,+,a1a2);
+ SET3 (cp2,b1,+,b1b2);
+
+# undef SET2
+# undef SET3
+}
+
+
+// a simple root finding algorithm is used to find the value of 't' that
+// satisfies:
+// d|D(t)|^2/dt = 0
+// where:
+// |D(t)| = |p(t)-b(t)|
+// where p(t) is a point on the line parameterized by t:
+// p(t) = p1 + t*(p2-p1)
+// and b(t) is that same point clipped to the boundary of the box. in box-
+// relative coordinates d|D(t)|^2/dt is the sum of three x,y,z components
+// each of which looks like this:
+//
+// t_lo /
+// ______/ -->t
+// / t_hi
+// /
+//
+// t_lo and t_hi are the t values where the line passes through the planes
+// corresponding to the sides of the box. the algorithm computes d|D(t)|^2/dt
+// in a piecewise fashion from t=0 to t=1, stopping at the point where
+// d|D(t)|^2/dt crosses from negative to positive.
+
+void dClosestLineBoxPoints (const dVector3 p1, const dVector3 p2,
+ const dVector3 c, const dMatrix3 R,
+ const dVector3 side,
+ dVector3 lret, dVector3 bret)
+{
+ int i;
+
+ // compute the start and delta of the line p1-p2 relative to the box.
+ // we will do all subsequent computations in this box-relative coordinate
+ // system. we have to do a translation and rotation for each point.
+ dVector3 tmp,s,v;
+ tmp[0] = p1[0] - c[0];
+ tmp[1] = p1[1] - c[1];
+ tmp[2] = p1[2] - c[2];
+ dMULTIPLY1_331 (s,R,tmp);
+ tmp[0] = p2[0] - p1[0];
+ tmp[1] = p2[1] - p1[1];
+ tmp[2] = p2[2] - p1[2];
+ dMULTIPLY1_331 (v,R,tmp);
+
+ // mirror the line so that v has all components >= 0
+ dVector3 sign;
+ for (i=0; i<3; i++) {
+ if (v[i] < 0) {
+ s[i] = -s[i];
+ v[i] = -v[i];
+ sign[i] = REAL(-1.0);
+ }
+ else sign[i] = REAL(1.0);
+ }
+
+ // compute v^2
+ dVector3 v2;
+ v2[0] = dMUL(v[0],v[0]);
+ v2[1] = dMUL(v[1],v[1]);
+ v2[2] = dMUL(v[2],v[2]);
+
+ // compute the half-sides of the box
+ dReal h[3];
+ h[0] = dMUL(REAL(0.5),side[0]);
+ h[1] = dMUL(REAL(0.5),side[1]);
+ h[2] = dMUL(REAL(0.5),side[2]);
+
+ // region is -1,0,+1 depending on which side of the box planes each
+ // coordinate is on. tanchor is the next t value at which there is a
+ // transition, or the last one if there are no more.
+ int region[3];
+ dReal tanchor[3];
+
+ // Denormals are a problem, because we divide by v[i], and then
+ // multiply that by 0. Alas, infinity times 0 is infinity (!)
+ // We also use v2[i], which is v[i] squared. Here's how the epsilons
+ // are chosen:
+ // float epsilon = 1.175494e-038 (smallest non-denormal number)
+ // double epsilon = 2.225074e-308 (smallest non-denormal number)
+ // For single precision, choose an epsilon such that v[i] squared is
+ // not a denormal; this is for performance.
+ // For double precision, choose an epsilon such that v[i] is not a
+ // denormal; this is for correctness. (Jon Watte on mailinglist)
+
+ const dReal tanchor_eps = REAL(2e-5f);
+
+ // find the region and tanchor values for p1
+ for (i=0; i<3; i++) {
+ if (v[i] > tanchor_eps) {
+ if (s[i] < -h[i]) {
+ region[i] = -1;
+ tanchor[i] = dDIV((-h[i]-s[i]),v[i]);
+ }
+ else {
+ region[i] = (s[i] > h[i]);
+ tanchor[i] = dDIV((h[i]-s[i]),v[i]);
+ }
+ }
+ else {
+ region[i] = 0;
+ tanchor[i] = REAL(2.0); // this will never be a valid tanchor
+ }
+ }
+
+ // compute d|d|^2/dt for t=0. if it's >= 0 then p1 is the closest point
+ dReal t = 0;
+ dReal dd2dt = 0;
+ for (i=0; i<3; i++) dd2dt -= dMUL((region[i] ? v2[i] : 0),tanchor[i]);
+ if (dd2dt >= 0) goto got_answer;
+
+ do {
+ // find the point on the line that is at the next clip plane boundary
+ dReal next_t = REAL(1.0);
+ for (i=0; i<3; i++) {
+ if (tanchor[i] > t && tanchor[i] < 1 && tanchor[i] < next_t)
+ next_t = tanchor[i];
+ }
+
+ // compute d|d|^2/dt for the next t
+ dReal next_dd2dt = REAL(0.0);
+ for (i=0; i<3; i++) {
+ next_dd2dt += dMUL((region[i] ? v2[i] : 0),(next_t - tanchor[i]));
+ }
+
+ // if the sign of d|d|^2/dt has changed, solution = the crossover point
+ if (next_dd2dt >= 0) {
+ dReal m = dDIV((next_dd2dt-dd2dt),(next_t - t));
+ t -= dDIV(dd2dt,m);
+ goto got_answer;
+ }
+
+ // advance to the next anchor point / region
+ for (i=0; i<3; i++) {
+ if (tanchor[i] == next_t) {
+ tanchor[i] = dDIV((h[i]-s[i]),v[i]);
+ region[i]++;
+ }
+ }
+ t = next_t;
+ dd2dt = next_dd2dt;
+ }
+ while (t < REAL(1.0));
+ t = REAL(1.0);
+
+ got_answer:
+
+ // compute closest point on the line
+ for (i=0; i<3; i++) lret[i] = p1[i] + dMUL(t,tmp[i]); // note: tmp=p2-p1
+
+ // compute closest point on the box
+ for (i=0; i<3; i++) {
+ tmp[i] = dMUL(sign[i],(s[i] + dMUL(t,v[i])));
+ if (tmp[i] < -h[i]) tmp[i] = -h[i];
+ else if (tmp[i] > h[i]) tmp[i] = h[i];
+ }
+ dMULTIPLY0_331 (s,R,tmp);
+ for (i=0; i<3; i++) bret[i] = s[i] + c[i];
+}
+
+
+// given boxes (p1,R1,side1) and (p1,R1,side1), return 1 if they intersect
+// or 0 if not.
+
+EXPORT_C int dBoxTouchesBox (const dVector3 p1, const dMatrix3 R1,
+ const dVector3 side1, const dVector3 p2,
+ const dMatrix3 R2, const dVector3 side2)
+{
+ // two boxes are disjoint if (and only if) there is a separating axis
+ // perpendicular to a face from one box or perpendicular to an edge from
+ // either box. the following tests are derived from:
+ // "OBB Tree: A Hierarchical Structure for Rapid Interference Detection",
+ // S.Gottschalk, M.C.Lin, D.Manocha., Proc of ACM Siggraph 1996.
+
+ // Rij is R1'*R2, i.e. the relative rotation between R1 and R2.
+ // Qij is abs(Rij)
+ dVector3 p,pp;
+ dReal A1,A2,A3,B1,B2,B3,R11,R12,R13,R21,R22,R23,R31,R32,R33,
+ Q11,Q12,Q13,Q21,Q22,Q23,Q31,Q32,Q33;
+
+ // get vector from centers of box 1 to box 2, relative to box 1
+ p[0] = p2[0] - p1[0];
+ p[1] = p2[1] - p1[1];
+ p[2] = p2[2] - p1[2];
+ dMULTIPLY1_331 (pp,R1,p); // get pp = p relative to body 1
+
+ // get side lengths / 2
+ A1 = dMUL(side1[0],REAL(0.5)); A2 = dMUL(side1[1],REAL(0.5)); A3 = dMUL(side1[2],REAL(0.5));
+ B1 = dMUL(side2[0],REAL(0.5)); B2 = dMUL(side2[1],REAL(0.5)); B3 = dMUL(side2[2],REAL(0.5));
+
+ // for the following tests, excluding computation of Rij, in the worst case,
+ // 15 compares, 60 adds, 81 multiplies, and 24 absolutes.
+ // notation: R1=[u1 u2 u3], R2=[v1 v2 v3]
+
+ // separating axis = u1,u2,u3
+ R11 = dDOT44(R1+0,R2+0); R12 = dDOT44(R1+0,R2+1); R13 = dDOT44(R1+0,R2+2);
+ Q11 = dFabs(R11); Q12 = dFabs(R12); Q13 = dFabs(R13);
+ if (dFabs(pp[0]) > (A1 + dMUL(B1,Q11) + dMUL(B2,Q12) + dMUL(B3,Q13))) return 0;
+ R21 = dDOT44(R1+1,R2+0); R22 = dDOT44(R1+1,R2+1); R23 = dDOT44(R1+1,R2+2);
+ Q21 = dFabs(R21); Q22 = dFabs(R22); Q23 = dFabs(R23);
+ if (dFabs(pp[1]) > (A2 + dMUL(B1,Q21) + dMUL(B2,Q22) + dMUL(B3,Q23))) return 0;
+ R31 = dDOT44(R1+2,R2+0); R32 = dDOT44(R1+2,R2+1); R33 = dDOT44(R1+2,R2+2);
+ Q31 = dFabs(R31); Q32 = dFabs(R32); Q33 = dFabs(R33);
+ if (dFabs(pp[2]) > (A3 + dMUL(B1,Q31) + dMUL(B2,Q32) + dMUL(B3,Q33))) return 0;
+
+ // separating axis = v1,v2,v3
+ if (dFabs(dDOT41(R2+0,p)) > (dMUL(A1,Q11) + dMUL(A2,Q21) + dMUL(A3,Q31) + B1)) return 0;
+ if (dFabs(dDOT41(R2+1,p)) > (dMUL(A1,Q12) + dMUL(A2,Q22) + dMUL(A3,Q32) + B2)) return 0;
+ if (dFabs(dDOT41(R2+2,p)) > (dMUL(A1,Q13) + dMUL(A2,Q23) + dMUL(A3,Q33) + B3)) return 0;
+
+ // separating axis = u1 x (v1,v2,v3)
+ if (dFabs(dMUL(pp[2],R21)-dMUL(pp[1],R31)) > dMUL(A2,Q31) + dMUL(A3,Q21) + dMUL(B2,Q13) + dMUL(B3,Q12)) return 0;
+ if (dFabs(dMUL(pp[2],R22)-dMUL(pp[1],R32)) > dMUL(A2,Q32) + dMUL(A3,Q22) + dMUL(B1,Q13) + dMUL(B3,Q11)) return 0;
+ if (dFabs(dMUL(pp[2],R23)-dMUL(pp[1],R33)) > dMUL(A2,Q33) + dMUL(A3,Q23) + dMUL(B1,Q12) + dMUL(B2,Q11)) return 0;
+
+ // separating axis = u2 x (v1,v2,v3)
+ if (dFabs(dMUL(pp[0],R31)-dMUL(pp[2],R11)) > dMUL(A1,Q31) + dMUL(A3,Q11) + dMUL(B2,Q23) + dMUL(B3,Q22)) return 0;
+ if (dFabs(dMUL(pp[0],R32)-dMUL(pp[2],R12)) > dMUL(A1,Q32) + dMUL(A3,Q12) + dMUL(B1,Q23) + dMUL(B3,Q21)) return 0;
+ if (dFabs(pp[0]*R33-pp[2]*R13) > A1*Q33 + A3*Q13 + B1*Q22 + B2*Q21) return 0;
+
+ // separating axis = u3 x (v1,v2,v3)
+ if (dFabs(dMUL(pp[1],R11)-dMUL(pp[0],R21)) > dMUL(A1,Q21) + dMUL(A2,Q11) + dMUL(B2,Q33) + dMUL(B3,Q32)) return 0;
+ if (dFabs(dMUL(pp[1],R12)-dMUL(pp[0],R22)) > dMUL(A1,Q22) + dMUL(A2,Q12) + dMUL(B1,Q33) + dMUL(B3,Q31)) return 0;
+ if (dFabs(dMUL(pp[1],R13)-dMUL(pp[0],R23)) > dMUL(A1,Q23) + dMUL(A2,Q13) + dMUL(B1,Q32) + dMUL(B2,Q31)) return 0;
+
+ return 1;
+}
+
+//****************************************************************************
+// other utility functions
+
+EXPORT_C void dInfiniteAABB (dxGeom */*geom*/, dReal aabb[6])
+{
+ aabb[0] = -dInfinity;
+ aabb[1] = dInfinity;
+ aabb[2] = -dInfinity;
+ aabb[3] = dInfinity;
+ aabb[4] = -dInfinity;
+ aabb[5] = dInfinity;
+}
+
+
+//****************************************************************************
+// Helpers for Croteam's collider - by Nguyen Binh
+
+int dClipEdgeToPlane( dVector3 &vEpnt0, dVector3 &vEpnt1, const dVector4& plPlane)
+{
+ // calculate distance of edge points to plane
+ dReal fDistance0 = dPointPlaneDistance( vEpnt0 ,plPlane );
+ dReal fDistance1 = dPointPlaneDistance( vEpnt1 ,plPlane );
+
+ // if both points are behind the plane
+ if ( fDistance0 < 0 && fDistance1 < 0 )
+ {
+ // do nothing
+ return 0;
+ // if both points in front of the plane
+ }
+ else if ( fDistance0 > 0 && fDistance1 > 0 )
+ {
+ // accept them
+ return 1;
+ // if we have edge/plane intersection
+ } else if ((fDistance0 > 0 && fDistance1 < 0) || ( fDistance0 < 0 && fDistance1 > 0))
+ {
+
+ // find intersection point of edge and plane
+ dVector3 vIntersectionPoint;
+ vIntersectionPoint[0]= vEpnt0[0]-dMUL((vEpnt0[0]-vEpnt1[0]),dDIV(fDistance0,(fDistance0-fDistance1)));
+ vIntersectionPoint[1]= vEpnt0[1]-dMUL((vEpnt0[1]-vEpnt1[1]),dDIV(fDistance0,(fDistance0-fDistance1)));
+ vIntersectionPoint[2]= vEpnt0[2]-dMUL((vEpnt0[2]-vEpnt1[2]),dDIV(fDistance0,(fDistance0-fDistance1)));
+
+ // clamp correct edge to intersection point
+ if ( fDistance0 < REAL(0.0) )
+ {
+ dVector3Copy(vIntersectionPoint,vEpnt0);
+ } else
+ {
+ dVector3Copy(vIntersectionPoint,vEpnt1);
+ }
+ return 1;
+ }
+ return 1;
+}
+
+// clip polygon with plane and generate new polygon points
+void dClipPolyToPlane( const dVector3 avArrayIn[], const int ctIn,
+ dVector3 avArrayOut[], int &ctOut,
+ const dVector4 &plPlane )
+{
+ // start with no output points
+ ctOut = 0;
+
+ int i0 = ctIn-1;
+
+ // for each edge in input polygon
+ for (int i1=0; i1<ctIn; i0=i1, i1++) {
+
+
+ // calculate distance of edge points to plane
+ dReal fDistance0 = dPointPlaneDistance( avArrayIn[i0],plPlane );
+ dReal fDistance1 = dPointPlaneDistance( avArrayIn[i1],plPlane );
+
+ // if first point is in front of plane
+ if( fDistance0 >= 0 ) {
+ // emit point
+ avArrayOut[ctOut][0] = avArrayIn[i0][0];
+ avArrayOut[ctOut][1] = avArrayIn[i0][1];
+ avArrayOut[ctOut][2] = avArrayIn[i0][2];
+ ctOut++;
+ }
+
+ // if points are on different sides
+ if( (fDistance0 > 0 && fDistance1 < 0) || ( fDistance0 < 0 && fDistance1 > 0) ) {
+
+ // find intersection point of edge and plane
+ dVector3 vIntersectionPoint;
+ vIntersectionPoint[0]= avArrayIn[i0][0] -
+ dMUL((avArrayIn[i0][0]-avArrayIn[i1][0]),dDIV(fDistance0,(fDistance0-fDistance1)));
+ vIntersectionPoint[1]= avArrayIn[i0][1] -
+ dMUL((avArrayIn[i0][1]-avArrayIn[i1][1]),dDIV(fDistance0,(fDistance0-fDistance1)));
+ vIntersectionPoint[2]= avArrayIn[i0][2] -
+ dMUL((avArrayIn[i0][2]-avArrayIn[i1][2]),dDIV(fDistance0,(fDistance0-fDistance1)));
+
+ // emit intersection point
+ avArrayOut[ctOut][0] = vIntersectionPoint[0];
+ avArrayOut[ctOut][1] = vIntersectionPoint[1];
+ avArrayOut[ctOut][2] = vIntersectionPoint[2];
+ ctOut++;
+ }
+ }
+
+}
+
+void dClipPolyToCircle(const dVector3 avArrayIn[], const int ctIn,
+ dVector3 avArrayOut[], int &ctOut,
+ const dVector4 &plPlane ,dReal fRadius)
+{
+ // start with no output points
+ ctOut = 0;
+
+ int i0 = ctIn-1;
+
+ // for each edge in input polygon
+ for (int i1=0; i1<ctIn; i0=i1, i1++)
+ {
+ // calculate distance of edge points to plane
+ dReal fDistance0 = dPointPlaneDistance( avArrayIn[i0],plPlane );
+ dReal fDistance1 = dPointPlaneDistance( avArrayIn[i1],plPlane );
+
+ // if first point is in front of plane
+ if( fDistance0 >= 0 )
+ {
+ // emit point
+ if (dVector3Length2(avArrayIn[i0]) <= dMUL(fRadius,fRadius))
+ {
+ avArrayOut[ctOut][0] = avArrayIn[i0][0];
+ avArrayOut[ctOut][1] = avArrayIn[i0][1];
+ avArrayOut[ctOut][2] = avArrayIn[i0][2];
+ ctOut++;
+ }
+ }
+
+ // if points are on different sides
+ if( (fDistance0 > 0 && fDistance1 < 0) || ( fDistance0 < 0 && fDistance1 > 0) )
+ {
+
+ // find intersection point of edge and plane
+ dVector3 vIntersectionPoint;
+ vIntersectionPoint[0]= avArrayIn[i0][0] -
+ dMUL((avArrayIn[i0][0]-avArrayIn[i1][0]),dDIV(fDistance0,(fDistance0-fDistance1)));
+ vIntersectionPoint[1]= avArrayIn[i0][1] -
+ dMUL((avArrayIn[i0][1]-avArrayIn[i1][1]),dDIV(fDistance0,(fDistance0-fDistance1)));
+ vIntersectionPoint[2]= avArrayIn[i0][2] -
+ dMUL((avArrayIn[i0][2]-avArrayIn[i1][2]),dDIV(fDistance0,(fDistance0-fDistance1)));
+
+ // emit intersection point
+ if (dVector3Length2(avArrayIn[i0]) <= dMUL(fRadius,fRadius))
+ {
+ avArrayOut[ctOut][0] = vIntersectionPoint[0];
+ avArrayOut[ctOut][1] = vIntersectionPoint[1];
+ avArrayOut[ctOut][2] = vIntersectionPoint[2];
+ ctOut++;
+ }
+ }
+ }
+}
+