add ode

1 files changed, 878 insertions, 0 deletions

diff --git a/libs/ode-0.16.1/ode/src/box.cpp b/libs/ode-0.16.1/ode/src/box.cpp
new file mode 100644
index 0000000..cfedb01
--- /dev/null
+++ b/libs/ode-0.16.1/ode/src/box.cpp
@@ -0,0 +1,878 @@
+/*************************************************************************
+ *                                                                       *
+ * Open Dynamics Engine, Copyright (C) 2001-2003 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.                     *
+ *                                                                       *
+ *************************************************************************/
+
+/*
+
+  standard ODE geometry primitives: public API and pairwise collision functions.
+
+  the rule is that only the low level primitive collision functions should set
+  dContactGeom::g1 and dContactGeom::g2.
+
+*/
+
+#include <ode/common.h>
+#include <ode/collision.h>
+#include <ode/rotation.h>
+#include "config.h"
+#include "matrix.h"
+#include "odemath.h"
+#include "collision_kernel.h"
+#include "collision_std.h"
+#include "collision_util.h"
+
+#ifdef _MSC_VER
+#pragma warning(disable:4291)  // for VC++, no complaints about "no matching operator delete found"
+#endif
+
+//****************************************************************************
+// box public API
+
+dxBox::dxBox (dSpaceID space, dReal lx, dReal ly, dReal lz) : dxGeom (space,1)
+{
+    dAASSERT (lx >= 0 && ly >= 0 && lz >= 0);
+    type = dBoxClass;
+    side[0] = lx;
+    side[1] = ly;
+    side[2] = lz;
+    updateZeroSizedFlag(!lx || !ly || !lz);
+}
+
+
+void dxBox::computeAABB()
+{
+    const dMatrix3& R = final_posr->R;
+    const dVector3& pos = final_posr->pos;
+
+    dReal xrange = REAL(0.5) * (dFabs (R[0] * side[0]) +
+        dFabs (R[1] * side[1]) + dFabs (R[2] * side[2]));
+    dReal yrange = REAL(0.5) * (dFabs (R[4] * side[0]) +
+        dFabs (R[5] * side[1]) + dFabs (R[6] * side[2]));
+    dReal zrange = REAL(0.5) * (dFabs (R[8] * side[0]) +
+        dFabs (R[9] * side[1]) + dFabs (R[10] * side[2]));
+    aabb[0] = pos[0] - xrange;
+    aabb[1] = pos[0] + xrange;
+    aabb[2] = pos[1] - yrange;
+    aabb[3] = pos[1] + yrange;
+    aabb[4] = pos[2] - zrange;
+    aabb[5] = pos[2] + zrange;
+}
+
+
+dGeomID dCreateBox (dSpaceID space, dReal lx, dReal ly, dReal lz)
+{
+    return new dxBox (space,lx,ly,lz);
+}
+
+
+void dGeomBoxSetLengths (dGeomID g, dReal lx, dReal ly, dReal lz)
+{
+    dUASSERT (g && g->type == dBoxClass,"argument not a box");
+    dAASSERT (lx >= 0 && ly >= 0 && lz >= 0);
+    dxBox *b = (dxBox*) g;
+    b->side[0] = lx;
+    b->side[1] = ly;
+    b->side[2] = lz;
+    b->updateZeroSizedFlag(!lx || !ly || !lz);
+    dGeomMoved (g);
+}
+
+
+void dGeomBoxGetLengths (dGeomID g, dVector3 result)
+{
+    dUASSERT (g && g->type == dBoxClass,"argument not a box");
+    dxBox *b = (dxBox*) g;
+    result[0] = b->side[0];
+    result[1] = b->side[1];
+    result[2] = b->side[2];
+}
+
+
+dReal dGeomBoxPointDepth (dGeomID g, dReal x, dReal y, dReal z)
+{
+    dUASSERT (g && g->type == dBoxClass,"argument not a box");
+    g->recomputePosr();
+    dxBox *b = (dxBox*) g;
+
+    // Set p = (x,y,z) relative to box center
+    //
+    // This will be (0,0,0) if the point is at (side[0]/2,side[1]/2,side[2]/2)
+
+    dVector3 p,q;
+
+    p[0] = x - b->final_posr->pos[0];
+    p[1] = y - b->final_posr->pos[1];
+    p[2] = z - b->final_posr->pos[2];
+
+    // Rotate p into box's coordinate frame, so we can
+    // treat the OBB as an AABB
+
+    dMultiply1_331 (q,b->final_posr->R,p);
+
+    // Record distance from point to each successive box side, and see
+    // if the point is inside all six sides
+
+    dReal dist[6];
+    int   i;
+
+    bool inside = true;
+
+    for (i=0; i < 3; i++) {
+        dReal side = b->side[i] * REAL(0.5);
+
+        dist[i  ] = side - q[i];
+        dist[i+3] = side + q[i];
+
+        if ((dist[i] < 0) || (dist[i+3] < 0)) {
+            inside = false;
+        }
+    }
+
+    // If point is inside the box, the depth is the smallest positive distance
+    // to any side
+
+    if (inside) {
+        dReal smallest_dist = (dReal) (unsigned) -1;
+
+        for (i=0; i < 6; i++) {
+            if (dist[i] < smallest_dist) smallest_dist = dist[i];
+        }
+
+        return smallest_dist;
+    }
+
+    // Otherwise, if point is outside the box, the depth is the largest
+    // distance to any side.  This is an approximation to the 'proper'
+    // solution (the proper solution may be larger in some cases).
+
+    dReal largest_dist = 0;
+
+    for (i=0; i < 6; i++) {
+        if (dist[i] > largest_dist) largest_dist = dist[i];
+    }
+
+    return -largest_dist;
+}
+
+//****************************************************************************
+// box-box collision utility
+
+
+// find all the intersection points between the 2D rectangle with vertices
+// at (+/-h[0],+/-h[1]) and the 2D quadrilateral with vertices (p[0],p[1]),
+// (p[2],p[3]),(p[4],p[5]),(p[6],p[7]).
+//
+// the intersection points are returned as x,y pairs in the 'ret' array.
+// the number of intersection points is returned by the function (this will
+// be in the range 0 to 8).
+
+static int intersectRectQuad (dReal h[2], dReal p[8], dReal ret[16])
+{
+    // q (and r) contain nq (and nr) coordinate points for the current (and
+    // chopped) polygons
+    int nq=4,nr;
+    dReal buffer[16];
+    dReal *q = p;
+    dReal *r = ret;
+    for (int dir=0; dir <= 1; dir++) {
+        // direction notation: xy[0] = x axis, xy[1] = y axis
+        for (int sign=-1; sign <= 1; sign += 2) {
+            // chop q along the line xy[dir] = sign*h[dir]
+            dReal *pq = q;
+            dReal *pr = r;
+            nr = 0;
+            for (int i=nq; i > 0; i--) {
+                // go through all points in q and all lines between adjacent points
+                if (sign*pq[dir] < h[dir]) {
+                    // this point is inside the chopping line
+                    pr[0] = pq[0];
+                    pr[1] = pq[1];
+                    pr += 2;
+                    nr++;
+                    if (nr & 8) {
+                        q = r;
+                        goto done;
+                    }
+                }
+                dReal *nextq = (i > 1) ? pq+2 : q;
+                if ((sign*pq[dir] < h[dir]) ^ (sign*nextq[dir] < h[dir])) {
+                    // this line crosses the chopping line
+                    pr[1-dir] = pq[1-dir] + (nextq[1-dir]-pq[1-dir]) /
+                        (nextq[dir]-pq[dir]) * (sign*h[dir]-pq[dir]);
+                    pr[dir] = sign*h[dir];
+                    pr += 2;
+                    nr++;
+                    if (nr & 8) {
+                        q = r;
+                        goto done;
+                    }
+                }
+                pq += 2;
+            }
+            q = r;
+            r = (q==ret) ? buffer : ret;
+            nq = nr;
+        }
+    }
+done:
+    if (q != ret) memcpy (ret,q,nr*2*sizeof(dReal));
+    return nr;
+}
+
+
+// given n points in the plane (array p, of size 2*n), generate m points that
+// best represent the whole set. the definition of 'best' here is not
+// predetermined - the idea is to select points that give good box-box
+// collision detection behavior. the chosen point indexes are returned in the
+// array iret (of size m). 'i0' is always the first entry in the array.
+// n must be in the range [1..8]. m must be in the range [1..n]. i0 must be
+// in the range [0..n-1].
+
+void cullPoints (int n, dReal p[], int m, int i0, int iret[])
+{
+    // compute the centroid of the polygon in cx,cy
+    int i,j;
+    dReal a,cx,cy,q;
+    if (n==1) {
+        cx = p[0];
+        cy = p[1];
+    }
+    else if (n==2) {
+        cx = REAL(0.5)*(p[0] + p[2]);
+        cy = REAL(0.5)*(p[1] + p[3]);
+    }
+    else {
+        a = 0;
+        cx = 0;
+        cy = 0;
+        for (i=0; i<(n-1); i++) {
+            q = p[i*2]*p[i*2+3] - p[i*2+2]*p[i*2+1];
+            a += q;
+            cx += q*(p[i*2]+p[i*2+2]);
+            cy += q*(p[i*2+1]+p[i*2+3]);
+        }
+        q = p[n*2-2]*p[1] - p[0]*p[n*2-1];
+        a = dRecip(REAL(3.0)*(a+q));
+        cx = a*(cx + q*(p[n*2-2]+p[0]));
+        cy = a*(cy + q*(p[n*2-1]+p[1]));
+    }
+
+    // compute the angle of each point w.r.t. the centroid
+    dReal A[8];
+    for (i=0; i<n; i++) A[i] = dAtan2(p[i*2+1]-cy,p[i*2]-cx);
+
+    // search for points that have angles closest to A[i0] + i*(2*pi/m).
+    int avail[8];
+    for (i=0; i<n; i++) avail[i] = 1;
+    avail[i0] = 0;
+    iret[0] = i0;
+    iret++;
+    for (j=1; j<m; j++) {
+        a = (dReal)(dReal(j)*(2*M_PI/m) + A[i0]);
+        if (a > M_PI) a -= (dReal)(2*M_PI);
+        dReal maxdiff=1e9,diff;
+#ifndef dNODEBUG
+        *iret = i0;			// iret is not allowed to keep this value
+#endif
+        for (i=0; i<n; i++) {
+            if (avail[i]) {
+                diff = dFabs (A[i]-a);
+                if (diff > M_PI) diff = (dReal) (2*M_PI - diff);
+                if (diff < maxdiff) {
+                    maxdiff = diff;
+                    *iret = i;
+                }
+            }
+        }
+#ifndef dNODEBUG
+        dIASSERT (*iret != i0);	// ensure iret got set
+#endif
+        avail[*iret] = 0;
+        iret++;
+    }
+}
+
+
+// given two boxes (p1,R1,side1) and (p2,R2,side2), collide them together and
+// generate contact points. this returns 0 if there is no contact otherwise
+// it returns the number of contacts generated.
+// `normal' returns the contact normal.
+// `depth' returns the maximum penetration depth along that normal.
+// `return_code' returns a number indicating the type of contact that was
+// detected:
+//        1,2,3 = box 2 intersects with a face of box 1
+//        4,5,6 = box 1 intersects with a face of box 2
+//        7..15 = edge-edge contact
+// `maxc' is the maximum number of contacts allowed to be generated, i.e.
+// the size of the `contact' array.
+// `contact' and `skip' are the contact array information provided to the
+// collision functions. this function only fills in the position and depth
+// fields.
+
+
+int dBoxBox (const dVector3 p1, const dMatrix3 R1,
+             const dVector3 side1, const dVector3 p2,
+             const dMatrix3 R2, const dVector3 side2,
+             dVector3 normal, dReal *depth, int *return_code,
+             int flags, dContactGeom *contact, int skip)
+{
+    const dReal fudge_factor = REAL(1.05);
+    dVector3 p,pp,normalC={0,0,0};
+    const dReal *normalR = 0;
+    dReal A[3],B[3],R11,R12,R13,R21,R22,R23,R31,R32,R33,
+        Q11,Q12,Q13,Q21,Q22,Q23,Q31,Q32,Q33,s,s2,l,expr1_val;
+    int i,j,invert_normal,code;
+
+    // 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
+    A[0] = side1[0]*REAL(0.5);
+    A[1] = side1[1]*REAL(0.5);
+    A[2] = side1[2]*REAL(0.5);
+    B[0] = side2[0]*REAL(0.5);
+    B[1] = side2[1]*REAL(0.5);
+    B[2] = side2[2]*REAL(0.5);
+
+    // Rij is R1'*R2, i.e. the relative rotation between R1 and R2
+    R11 = dCalcVectorDot3_44(R1+0,R2+0); R12 = dCalcVectorDot3_44(R1+0,R2+1); R13 = dCalcVectorDot3_44(R1+0,R2+2);
+    R21 = dCalcVectorDot3_44(R1+1,R2+0); R22 = dCalcVectorDot3_44(R1+1,R2+1); R23 = dCalcVectorDot3_44(R1+1,R2+2);
+    R31 = dCalcVectorDot3_44(R1+2,R2+0); R32 = dCalcVectorDot3_44(R1+2,R2+1); R33 = dCalcVectorDot3_44(R1+2,R2+2);
+
+    Q11 = dFabs(R11); Q12 = dFabs(R12); Q13 = dFabs(R13);
+    Q21 = dFabs(R21); Q22 = dFabs(R22); Q23 = dFabs(R23);
+    Q31 = dFabs(R31); Q32 = dFabs(R32); Q33 = dFabs(R33);
+
+    // for all 15 possible separating axes:
+    //   * see if the axis separates the boxes. if so, return 0.
+    //   * find the depth of the penetration along the separating axis (s2)
+    //   * if this is the largest depth so far, record it.
+    // the normal vector will be set to the separating axis with the smallest
+    // depth. note: normalR is set to point to a column of R1 or R2 if that is
+    // the smallest depth normal so far. otherwise normalR is 0 and normalC is
+    // set to a vector relative to body 1. invert_normal is 1 if the sign of
+    // the normal should be flipped.
+
+    do {
+#define TST(expr1,expr2,norm,cc) \
+    expr1_val = (expr1); /* Avoid duplicate evaluation of expr1 */ \
+    s2 = dFabs(expr1_val) - (expr2); \
+    if (s2 > 0) return 0; \
+    if (s2 > s) { \
+    s = s2; \
+    normalR = norm; \
+    invert_normal = ((expr1_val) < 0); \
+    code = (cc); \
+    if (flags & CONTACTS_UNIMPORTANT) break; \
+    }
+
+        s = -dInfinity;
+        invert_normal = 0;
+        code = 0;
+
+        // separating axis = u1,u2,u3
+        TST (pp[0],(A[0] + B[0]*Q11 + B[1]*Q12 + B[2]*Q13),R1+0,1);
+        TST (pp[1],(A[1] + B[0]*Q21 + B[1]*Q22 + B[2]*Q23),R1+1,2);
+        TST (pp[2],(A[2] + B[0]*Q31 + B[1]*Q32 + B[2]*Q33),R1+2,3);
+
+        // separating axis = v1,v2,v3
+        TST (dCalcVectorDot3_41(R2+0,p),(A[0]*Q11 + A[1]*Q21 + A[2]*Q31 + B[0]),R2+0,4);
+        TST (dCalcVectorDot3_41(R2+1,p),(A[0]*Q12 + A[1]*Q22 + A[2]*Q32 + B[1]),R2+1,5);
+        TST (dCalcVectorDot3_41(R2+2,p),(A[0]*Q13 + A[1]*Q23 + A[2]*Q33 + B[2]),R2+2,6);
+
+        // note: cross product axes need to be scaled when s is computed.
+        // normal (n1,n2,n3) is relative to box 1.
+#undef TST
+#define TST(expr1,expr2,n1,n2,n3,cc) \
+    expr1_val = (expr1); /* Avoid duplicate evaluation of expr1 */ \
+    s2 = dFabs(expr1_val) - (expr2); \
+    if (s2 > 0) return 0; \
+    l = dSqrt ((n1)*(n1) + (n2)*(n2) + (n3)*(n3)); \
+    if (l > 0) { \
+    s2 /= l; \
+    if (s2*fudge_factor > s) { \
+    s = s2; \
+    normalR = 0; \
+    normalC[0] = (n1)/l; normalC[1] = (n2)/l; normalC[2] = (n3)/l; \
+    invert_normal = ((expr1_val) < 0); \
+    code = (cc); \
+    if (flags & CONTACTS_UNIMPORTANT) break; \
+    } \
+    }
+
+        // We only need to check 3 edges per box 
+        // since parallel edges are equivalent.
+
+        // separating axis = u1 x (v1,v2,v3)
+        TST(pp[2]*R21-pp[1]*R31,(A[1]*Q31+A[2]*Q21+B[1]*Q13+B[2]*Q12),0,-R31,R21,7);
+        TST(pp[2]*R22-pp[1]*R32,(A[1]*Q32+A[2]*Q22+B[0]*Q13+B[2]*Q11),0,-R32,R22,8);
+        TST(pp[2]*R23-pp[1]*R33,(A[1]*Q33+A[2]*Q23+B[0]*Q12+B[1]*Q11),0,-R33,R23,9);
+
+        // separating axis = u2 x (v1,v2,v3)
+        TST(pp[0]*R31-pp[2]*R11,(A[0]*Q31+A[2]*Q11+B[1]*Q23+B[2]*Q22),R31,0,-R11,10);
+        TST(pp[0]*R32-pp[2]*R12,(A[0]*Q32+A[2]*Q12+B[0]*Q23+B[2]*Q21),R32,0,-R12,11);
+        TST(pp[0]*R33-pp[2]*R13,(A[0]*Q33+A[2]*Q13+B[0]*Q22+B[1]*Q21),R33,0,-R13,12);
+
+        // separating axis = u3 x (v1,v2,v3)
+        TST(pp[1]*R11-pp[0]*R21,(A[0]*Q21+A[1]*Q11+B[1]*Q33+B[2]*Q32),-R21,R11,0,13);
+        TST(pp[1]*R12-pp[0]*R22,(A[0]*Q22+A[1]*Q12+B[0]*Q33+B[2]*Q31),-R22,R12,0,14);
+        TST(pp[1]*R13-pp[0]*R23,(A[0]*Q23+A[1]*Q13+B[0]*Q32+B[1]*Q31),-R23,R13,0,15);
+#undef TST
+    } while (0);
+
+    if (!code) return 0;
+
+    // if we get to this point, the boxes interpenetrate. compute the normal
+    // in global coordinates.
+    if (normalR) {
+        normal[0] = normalR[0];
+        normal[1] = normalR[4];
+        normal[2] = normalR[8];
+    }
+    else {
+        dMultiply0_331 (normal,R1,normalC);
+    }
+    if (invert_normal) {
+        normal[0] = -normal[0];
+        normal[1] = -normal[1];
+        normal[2] = -normal[2];
+    }
+    *depth = -s;
+
+    // compute contact point(s)
+
+    if (code > 6) {
+        // An edge from box 1 touches an edge from box 2.
+        // find a point pa on the intersecting edge of box 1
+        dVector3 pa;
+        dReal sign;
+        // Copy p1 into pa
+        for (i=0; i<3; i++) pa[i] = p1[i]; // why no memcpy?
+        // Get world position of p2 into pa
+        for (j=0; j<3; j++) {
+            sign = (dCalcVectorDot3_14(normal,R1+j) > 0) ? REAL(1.0) : REAL(-1.0);
+            for (i=0; i<3; i++) pa[i] += sign * A[j] * R1[i*4+j];
+        }
+
+        // find a point pb on the intersecting edge of box 2
+        dVector3 pb;
+        // Copy p2 into pb
+        for (i=0; i<3; i++) pb[i] = p2[i]; // why no memcpy?
+        // Get world position of p2 into pb
+        for (j=0; j<3; j++) {
+            sign = (dCalcVectorDot3_14(normal,R2+j) > 0) ? REAL(-1.0) : REAL(1.0);
+            for (i=0; i<3; i++) pb[i] += sign * B[j] * R2[i*4+j];
+        }
+
+        dReal alpha,beta;
+        dVector3 ua,ub;
+        // Get direction of first edge
+        for (i=0; i<3; i++) ua[i] = R1[((code)-7)/3 + i*4];
+        // Get direction of second edge
+        for (i=0; i<3; i++) ub[i] = R2[((code)-7)%3 + i*4];
+        // Get closest points between edges (one at each)
+        dLineClosestApproach (pa,ua,pb,ub,&alpha,&beta);    
+        for (i=0; i<3; i++) pa[i] += ua[i]*alpha;
+        for (i=0; i<3; i++) pb[i] += ub[i]*beta;
+        // Set the contact point as halfway between the 2 closest points
+        for (i=0; i<3; i++) contact[0].pos[i] = REAL(0.5)*(pa[i]+pb[i]);
+        contact[0].depth = *depth;
+        *return_code = code;
+        return 1;
+    }
+
+    // okay, we have a face-something intersection (because the separating
+    // axis is perpendicular to a face). define face 'a' to be the reference
+    // face (i.e. the normal vector is perpendicular to this) and face 'b' to be
+    // the incident face (the closest face of the other box).
+    // Note: Unmodified parameter values are being used here
+    const dReal *Ra,*Rb,*pa,*pb,*Sa,*Sb;
+    if (code <= 3) { // One of the faces of box 1 is the reference face
+        Ra = R1; // Rotation of 'a'
+        Rb = R2; // Rotation of 'b'
+        pa = p1; // Center (location) of 'a'
+        pb = p2; // Center (location) of 'b'
+        Sa = A;  // Side Lenght of 'a'
+        Sb = B;  // Side Lenght of 'b'
+    }
+    else { // One of the faces of box 2 is the reference face
+        Ra = R2; // Rotation of 'a'
+        Rb = R1; // Rotation of 'b'
+        pa = p2; // Center (location) of 'a'
+        pb = p1; // Center (location) of 'b'
+        Sa = B;  // Side Lenght of 'a'
+        Sb = A;  // Side Lenght of 'b'
+    }
+
+    // nr = normal vector of reference face dotted with axes of incident box.
+    // anr = absolute values of nr.
+    /*
+    The normal is flipped if necessary so it always points outward from box 'a',
+    box 'b' is thus always the incident box
+    */
+    dVector3 normal2,nr,anr;
+    if (code <= 3) {
+        normal2[0] = normal[0];
+        normal2[1] = normal[1];
+        normal2[2] = normal[2];
+    }
+    else {
+        normal2[0] = -normal[0];
+        normal2[1] = -normal[1];
+        normal2[2] = -normal[2];
+    }
+    // Rotate normal2 in incident box opposite direction
+    dMultiply1_331 (nr,Rb,normal2);
+    anr[0] = dFabs (nr[0]);
+    anr[1] = dFabs (nr[1]);
+    anr[2] = dFabs (nr[2]);
+
+    // find the largest compontent of anr: this corresponds to the normal
+    // for the incident face. the other axis numbers of the incident face
+    // are stored in a1,a2.
+    int lanr,a1,a2;
+    if (anr[1] > anr[0]) {
+        if (anr[1] > anr[2]) {
+            a1 = 0;
+            lanr = 1;
+            a2 = 2;
+        }
+        else {
+            a1 = 0;
+            a2 = 1;
+            lanr = 2;
+        }
+    }
+    else {
+        if (anr[0] > anr[2]) {
+            lanr = 0;
+            a1 = 1;
+            a2 = 2;
+        }
+        else {
+            a1 = 0;
+            a2 = 1;
+            lanr = 2;
+        }
+    }
+
+    // compute center point of incident face, in reference-face coordinates
+    dVector3 center;
+    if (nr[lanr] < 0) {
+        for (i=0; i<3; i++) center[i] = pb[i] - pa[i] + Sb[lanr] * Rb[i*4+lanr];
+    }
+    else {
+        for (i=0; i<3; i++) center[i] = pb[i] - pa[i] - Sb[lanr] * Rb[i*4+lanr];
+    }
+
+    // find the normal and non-normal axis numbers of the reference box
+    int codeN,code1,code2;
+    if (code <= 3) codeN = code-1; else codeN = code-4;
+    if (codeN==0) {
+        code1 = 1;
+        code2 = 2;
+    }
+    else if (codeN==1) {
+        code1 = 0;
+        code2 = 2;
+    }
+    else {
+        code1 = 0;
+        code2 = 1;
+    }
+
+    // find the four corners of the incident face, in reference-face coordinates
+    dReal quad[8];	// 2D coordinate of incident face (x,y pairs)
+    dReal c1,c2,m11,m12,m21,m22;
+    c1 = dCalcVectorDot3_14 (center,Ra+code1);
+    c2 = dCalcVectorDot3_14 (center,Ra+code2);
+    // optimize this? - we have already computed this data above, but it is not
+    // stored in an easy-to-index format. for now it's quicker just to recompute
+    // the four dot products.
+    m11 = dCalcVectorDot3_44 (Ra+code1,Rb+a1);
+    m12 = dCalcVectorDot3_44 (Ra+code1,Rb+a2);
+    m21 = dCalcVectorDot3_44 (Ra+code2,Rb+a1);
+    m22 = dCalcVectorDot3_44 (Ra+code2,Rb+a2);
+    {
+        dReal k1 = m11*Sb[a1];
+        dReal k2 = m21*Sb[a1];
+        dReal k3 = m12*Sb[a2];
+        dReal k4 = m22*Sb[a2];
+        quad[0] = c1 - k1 - k3;
+        quad[1] = c2 - k2 - k4;
+        quad[2] = c1 - k1 + k3;
+        quad[3] = c2 - k2 + k4;
+        quad[4] = c1 + k1 + k3;
+        quad[5] = c2 + k2 + k4;
+        quad[6] = c1 + k1 - k3;
+        quad[7] = c2 + k2 - k4;
+    }
+
+    // find the size of the reference face
+    dReal rect[2];
+    rect[0] = Sa[code1];
+    rect[1] = Sa[code2];
+
+    // intersect the incident and reference faces
+    dReal ret[16];
+    int n = intersectRectQuad (rect,quad,ret);
+    if (n < 1) return 0;		// this should never happen
+
+    // convert the intersection points into reference-face coordinates,
+    // and compute the contact position and depth for each point. only keep
+    // those points that have a positive (penetrating) depth. delete points in
+    // the 'ret' array as necessary so that 'point' and 'ret' correspond.
+    dReal point[3*8];		// penetrating contact points
+    dReal dep[8];			// depths for those points
+    dReal det1 = dRecip(m11*m22 - m12*m21);
+    m11 *= det1;
+    m12 *= det1;
+    m21 *= det1;
+    m22 *= det1;
+    int cnum = 0;			// number of penetrating contact points found
+    for (j=0; j < n; j++) {
+        dReal k1 =  m22*(ret[j*2]-c1) - m12*(ret[j*2+1]-c2);
+        dReal k2 = -m21*(ret[j*2]-c1) + m11*(ret[j*2+1]-c2);
+        for (i=0; i<3; i++) point[cnum*3+i] =
+            center[i] + k1*Rb[i*4+a1] + k2*Rb[i*4+a2];
+        dep[cnum] = Sa[codeN] - dCalcVectorDot3(normal2,point+cnum*3);
+        if (dep[cnum] >= 0) {
+            ret[cnum*2] = ret[j*2];
+            ret[cnum*2+1] = ret[j*2+1];
+            cnum++;
+            if ((cnum | CONTACTS_UNIMPORTANT) == (flags & (NUMC_MASK | CONTACTS_UNIMPORTANT))) {
+                break;
+            }
+        }
+    }
+    if (cnum < 1) { 
+        return 0;	// this should not happen, yet does at times (demo_plane2d single precision).
+    }
+
+    // we can't generate more contacts than we actually have
+    int maxc = flags & NUMC_MASK;
+    if (maxc > cnum) maxc = cnum;
+    if (maxc < 1) maxc = 1;	// Even though max count must not be zero this check is kept for backward compatibility as this is a public function
+
+    if (cnum <= maxc) {
+        // we have less contacts than we need, so we use them all
+        for (j=0; j < cnum; j++) {
+            dContactGeom *con = CONTACT(contact,skip*j);
+            for (i=0; i<3; i++) con->pos[i] = point[j*3+i] + pa[i];
+            con->depth = dep[j];
+        }
+    }
+    else {
+        dIASSERT(!(flags & CONTACTS_UNIMPORTANT)); // cnum should be generated not greater than maxc so that "then" clause is executed
+        // we have more contacts than are wanted, some of them must be culled.
+        // find the deepest point, it is always the first contact.
+        int i1 = 0;
+        dReal maxdepth = dep[0];
+        for (i=1; i<cnum; i++) {
+            if (dep[i] > maxdepth) {
+                maxdepth = dep[i];
+                i1 = i;
+            }
+        }
+
+        int iret[8];
+        cullPoints (cnum,ret,maxc,i1,iret);
+
+        for (j=0; j < maxc; j++) {
+            dContactGeom *con = CONTACT(contact,skip*j);
+            for (i=0; i<3; i++) con->pos[i] = point[iret[j]*3+i] + pa[i];
+            con->depth = dep[iret[j]];
+        }
+        cnum = maxc;
+    }
+
+    *return_code = code;
+    return cnum;
+}
+
+
+
+int dCollideBoxBox (dxGeom *o1, dxGeom *o2, int flags,
+                    dContactGeom *contact, int skip)
+{
+    dIASSERT (skip >= (int)sizeof(dContactGeom));
+    dIASSERT (o1->type == dBoxClass);
+    dIASSERT (o2->type == dBoxClass);
+    dIASSERT ((flags & NUMC_MASK) >= 1);
+
+    dVector3 normal;
+    dReal depth;
+    int code;
+    dxBox *b1 = (dxBox*) o1;
+    dxBox *b2 = (dxBox*) o2;
+    int num = dBoxBox (o1->final_posr->pos,o1->final_posr->R,b1->side, o2->final_posr->pos,o2->final_posr->R,b2->side,
+        normal,&depth,&code,flags,contact,skip);
+    for (int i=0; i<num; i++) {
+        dContactGeom *currContact = CONTACT(contact,i*skip);
+        currContact->normal[0] = -normal[0];
+        currContact->normal[1] = -normal[1];
+        currContact->normal[2] = -normal[2];
+        currContact->g1 = o1;
+        currContact->g2 = o2;
+        currContact->side1 = -1;
+        currContact->side2 = -1;
+    }
+    return num;
+}
+
+
+int dCollideBoxPlane (dxGeom *o1, dxGeom *o2,
+                      int flags, dContactGeom *contact, int skip)
+{
+    dIASSERT (skip >= (int)sizeof(dContactGeom));
+    dIASSERT (o1->type == dBoxClass);
+    dIASSERT (o2->type == dPlaneClass);
+    dIASSERT ((flags & NUMC_MASK) >= 1);
+
+    dxBox *box = (dxBox*) o1;
+    dxPlane *plane = (dxPlane*) o2;
+
+    contact->g1 = o1;
+    contact->g2 = o2;
+    contact->side1 = -1;
+    contact->side2 = -1;
+
+    int ret = 0;
+
+    //@@@ problem: using 4-vector (plane->p) as 3-vector (normal).
+    const dReal *R = o1->final_posr->R;		// rotation of box
+    const dReal *n = plane->p;		// normal vector
+
+    // project sides lengths along normal vector, get absolute values
+    dReal Q1 = dCalcVectorDot3_14(n,R+0);
+    dReal Q2 = dCalcVectorDot3_14(n,R+1);
+    dReal Q3 = dCalcVectorDot3_14(n,R+2);
+    dReal A1 = box->side[0] * Q1;
+    dReal A2 = box->side[1] * Q2;
+    dReal A3 = box->side[2] * Q3;
+    dReal B1 = dFabs(A1);
+    dReal B2 = dFabs(A2);
+    dReal B3 = dFabs(A3);
+
+    // early exit test
+    dReal depth = plane->p[3] + REAL(0.5)*(B1+B2+B3) - dCalcVectorDot3(n,o1->final_posr->pos);
+    if (depth < 0) return 0;
+
+    // find number of contacts requested
+    int maxc = flags & NUMC_MASK;
+    // if (maxc < 1) maxc = 1; // an assertion is made on entry
+    if (maxc > 4) maxc = 4;	// not more than 4 contacts per box allowed
+
+    // find deepest point
+    dVector3 p;
+    p[0] = o1->final_posr->pos[0];
+    p[1] = o1->final_posr->pos[1];
+    p[2] = o1->final_posr->pos[2];
+#define FOO(i,op) \
+    p[0] op REAL(0.5)*box->side[i] * R[0+i]; \
+    p[1] op REAL(0.5)*box->side[i] * R[4+i]; \
+    p[2] op REAL(0.5)*box->side[i] * R[8+i];
+#define BAR(i,iinc) if (A ## iinc > 0) { FOO(i,-=) } else { FOO(i,+=) }
+    BAR(0,1);
+    BAR(1,2);
+    BAR(2,3);
+#undef FOO
+#undef BAR
+
+    // the deepest point is the first contact point
+    contact->pos[0] = p[0];
+    contact->pos[1] = p[1];
+    contact->pos[2] = p[2];
+    contact->depth = depth;
+    ret = 1;		// ret is number of contact points found so far
+    if (maxc == 1) goto done;
+
+    // get the second and third contact points by starting from `p' and going
+    // along the two sides with the smallest projected length.
+
+#define FOO(i,j,op) \
+    CONTACT(contact,i*skip)->pos[0] = p[0] op box->side[j] * R[0+j]; \
+    CONTACT(contact,i*skip)->pos[1] = p[1] op box->side[j] * R[4+j]; \
+    CONTACT(contact,i*skip)->pos[2] = p[2] op box->side[j] * R[8+j];
+#define BAR(ctact,side,sideinc) \
+    if (depth - B ## sideinc < 0) goto done; \
+    if (A ## sideinc > 0) { FOO(ctact,side,+); } else { FOO(ctact,side,-); } \
+    CONTACT(contact,ctact*skip)->depth = depth - B ## sideinc; \
+    ret++;
+
+    if (B1 < B2) {
+        if (B3 < B1) goto use_side_3; else {
+            BAR(1,0,1);	// use side 1
+            if (maxc == 2) goto done;
+            if (B2 < B3) goto contact2_2; else goto contact2_3;
+        }
+    }
+    else {
+        if (B3 < B2) {
+use_side_3:	// use side 3
+            BAR(1,2,3);
+            if (maxc == 2) goto done;
+            if (B1 < B2) goto contact2_1; else goto contact2_2;
+        }
+        else {
+            BAR(1,1,2);	// use side 2
+            if (maxc == 2) goto done;
+            if (B1 < B3) goto contact2_1; else goto contact2_3;
+        }
+    }
+
+contact2_1: BAR(2,0,1); goto done;
+contact2_2: BAR(2,1,2); goto done;
+contact2_3: BAR(2,2,3); goto done;
+#undef FOO
+#undef BAR
+
+done:
+
+    if (maxc == 4 && ret == 3) { // If user requested 4 contacts, and the first 3 were created...
+        // Combine contacts 2 and 3 (vectorial sum) and get the fourth one
+        // Result: if a box face is completely inside a plane, contacts are created for all the 4 vertices
+        dReal d4 = CONTACT(contact,1*skip)->depth + CONTACT(contact,2*skip)->depth - depth;  // depth is the depth for first contact
+        if (d4 > 0) {
+            CONTACT(contact,3*skip)->pos[0] = CONTACT(contact,1*skip)->pos[0] + CONTACT(contact,2*skip)->pos[0] - p[0]; // p is the position of first contact
+            CONTACT(contact,3*skip)->pos[1] = CONTACT(contact,1*skip)->pos[1] + CONTACT(contact,2*skip)->pos[1] - p[1];
+            CONTACT(contact,3*skip)->pos[2] = CONTACT(contact,1*skip)->pos[2] + CONTACT(contact,2*skip)->pos[2] - p[2];
+            CONTACT(contact,3*skip)->depth  = d4;
+            ret++;
+        }
+    }
+
+    for (int i=0; i<ret; i++) {
+        dContactGeom *currContact = CONTACT(contact,i*skip);
+        currContact->g1 = o1;
+        currContact->g2 = o2;
+        currContact->side1 = -1;
+        currContact->side2 = -1;
+
+        currContact->normal[0] = n[0];
+        currContact->normal[1] = n[1];
+        currContact->normal[2] = n[2];
+    }
+    return ret;
+}