/*
this is code that was once useful but has now been obseleted.
this file should not be compiled as part of ODE!
*/
//***************************************************************************
// intersect a line segment with a plane
extern "C" int dClipLineToBox (const dVector3 p1, const dVector3 p2,
const dVector3 p, const dMatrix3 R,
const dVector3 side)
{
// compute the start and end of the line (p1 and 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,e;
tmp[0] = p1[0] - p[0];
tmp[1] = p1[1] - p[1];
tmp[2] = p1[2] - p[2];
dMULTIPLY1_331 (s,R,tmp);
tmp[0] = p2[0] - p[0];
tmp[1] = p2[1] - p[1];
tmp[2] = p2[2] - p[2];
dMULTIPLY1_331 (e,R,tmp);
// compute the vector 'v' from the start point to the end point
dVector3 v;
v[0] = e[0] - s[0];
v[1] = e[1] - s[1];
v[2] = e[2] - s[2];
// a point on the line is defined by the parameter 't'. t=0 corresponds
// to the start of the line, t=1 corresponds to the end of the line.
// we will clip the line to the box by finding the range of t where a
// point on the line is inside the box. the currently known bounds for
// t and tlo..thi.
dReal tlo=0,thi=1;
// clip in the X/Y/Z direction
for (int i=0; i<3; i++) {
// first adjust s,e for the current t range. this is redundant for the
// first iteration, but never mind.
e[i] = s[i] + thi*v[i];
s[i] = s[i] + tlo*v[i];
// compute where t intersects the positive and negative sides.
dReal tp = ( side[i] - s[i])/v[i]; // @@@ handle case where denom=0
dReal tm = (-side[i] - s[i])/v[i];
// handle 9 intersection cases
if (s[i] <= -side[i]) {
tlo = tm;
if (e[i] <= -side[i]) return 0;
else if (e[i] >= side[i]) thi = tp;
}
else if (s[i] <= side[i]) {
if (e[i] <= -side[i]) thi = tm;
else if (e[i] >= side[i]) thi = tp;
}
else {
tlo = tp;
if (e[i] <= -side[i]) thi = tm;
else if (e[i] >= side[i]) return 0;
}
}
//... @@@ AT HERE @@@
return 1;
}
//***************************************************************************
// a nice try at C-B collision. unfortunately it doesn't work. the logic
// for testing for line-box intersection is correct, but unfortunately the
// closest-point distance estimates are often too large. as a result contact
// points are placed incorrectly.
int dCollideCB (const dxGeom *o1, const dxGeom *o2, int flags,
dContactGeom *contact, int skip)
{
int i;
dIASSERT (skip >= (int)sizeof(dContactGeom));
dIASSERT (o1->_class->num == dCCylinderClass);
dIASSERT (o2->_class->num == dBoxClass);
contact->g1 = const_cast<dxGeom*> (o1);
contact->g2 = const_cast<dxGeom*> (o2);
dxCCylinder *cyl = (dxCCylinder*) CLASSDATA(o1);
dxBox *box = (dxBox*) CLASSDATA(o2);
// get p1,p2 = cylinder axis endpoints, get radius
dVector3 p1,p2;
dReal clen = cyl->lz * REAL(0.5);
p1[0] = o1->pos[0] + clen * o1->R[2];
p1[1] = o1->pos[1] + clen * o1->R[6];
p1[2] = o1->pos[2] + clen * o1->R[10];
p2[0] = o1->pos[0] - clen * o1->R[2];
p2[1] = o1->pos[1] - clen * o1->R[6];
p2[2] = o1->pos[2] - clen * o1->R[10];
dReal radius = cyl->radius;
// copy out box center, rotation matrix, and side array
dReal *c = o2->pos;
dReal *R = o2->R;
dReal *side = box->side;
// compute the start and end of the line (p1 and 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 tmp3,s,e;
tmp3[0] = p1[0] - c[0];
tmp3[1] = p1[1] - c[1];
tmp3[2] = p1[2] - c[2];
dMULTIPLY1_331 (s,R,tmp3);
tmp3[0] = p2[0] - c[0];
tmp3[1] = p2[1] - c[1];
tmp3[2] = p2[2] - c[2];
dMULTIPLY1_331 (e,R,tmp3);
// compute the vector 'v' from the start point to the end point
dVector3 v;
v[0] = e[0] - s[0];
v[1] = e[1] - s[1];
v[2] = e[2] - s[2];
// compute the half-sides of the box
dReal S0 = side[0] * REAL(0.5);
dReal S1 = side[1] * REAL(0.5);
dReal S2 = side[2] * REAL(0.5);
// compute the size of the bounding box around the line segment
dReal B0 = dFabs (v[0]);
dReal B1 = dFabs (v[1]);
dReal B2 = dFabs (v[2]);
// for all 6 separation axes, measure the penetration depth. if any depth is
// less than 0 then the objects don't penetrate at all so we can just
// return 0. find the axis with the smallest depth, and record its normal.
// note: normalR is set to point to a column of R if that is the smallest
// depth normal so far. otherwise normalR is 0 and normalC is set to a
// vector relative to the box. invert_normal is 1 if the sign of the normal
// should be flipped.
dReal depth,trial_depth,tmp,length;
const dReal *normalR=0;
dVector3 normalC;
int invert_normal = 0;
int code = 0; // 0=no contact, 1-3=face contact, 4-6=edge contact
depth = dInfinity;
// look at face-normal axes
#undef TEST
#define TEST(center,depth_expr,norm,contact_code) \
tmp = (center); \
trial_depth = radius + REAL(0.5) * ((depth_expr) - dFabs(tmp)); \
if (trial_depth < 0) return 0; \
if (trial_depth < depth) { \
depth = trial_depth; \
normalR = (norm); \
invert_normal = (tmp < 0); \
code = contact_code; \
}
TEST (s[0]+e[0], side[0] + B0, R+0, 1);
TEST (s[1]+e[1], side[1] + B1, R+1, 2);
TEST (s[2]+e[2], side[2] + B2, R+2, 3);
// look at v x box-edge axes
#undef TEST
#define TEST(box_radius,line_offset,nx,ny,nz,contact_code) \
tmp = (line_offset); \
trial_depth = (box_radius) - dFabs(tmp); \
length = dSqrt ((nx)*(nx) + (ny)*(ny) + (nz)*(nz)); \
if (length > 0) { \
length = dRecip(length); \
trial_depth = trial_depth * length + radius; \
if (trial_depth < 0) return 0; \
if (trial_depth < depth) { \
depth = trial_depth; \
normalR = 0; \
normalC[0] = (nx)*length; \
normalC[1] = (ny)*length; \
normalC[2] = (nz)*length; \
invert_normal = (tmp < 0); \
code = contact_code; \
} \
}
TEST (B2*S1+B1*S2,v[1]*s[2]-v[2]*s[1], 0,-v[2],v[1], 4);
TEST (B2*S0+B0*S2,v[2]*s[0]-v[0]*s[2], v[2],0,-v[0], 5);
TEST (B1*S0+B0*S1,v[0]*s[1]-v[1]*s[0], -v[1],v[0],0, 6);
#undef TEST
// if we get to this point, the box and ccylinder interpenetrate.
// compute the normal in global coordinates.
dReal *normal = contact[0].normal;
if (normalR) {
normal[0] = normalR[0];
normal[1] = normalR[4];
normal[2] = normalR[8];
}
else {
dMULTIPLY0_331 (normal,R,normalC);
}
if (invert_normal) {
normal[0] = -normal[0];
normal[1] = -normal[1];
normal[2] = -normal[2];
}
// set the depth
contact[0].depth = depth;
if (code == 0) {
return 0; // should never get here
}
else if (code >= 4) {
// handle edge contacts
// find an endpoint q1 on the intersecting edge of the box
dVector3 q1;
dReal sign[3];
for (i=0; i<3; i++) q1[i] = c[i];
sign[0] = (dDOT14(normal,R+0) > 0) ? REAL(1.0) : REAL(-1.0);
for (i=0; i<3; i++) q1[i] += sign[0] * S0 * R[i*4];
sign[1] = (dDOT14(normal,R+1) > 0) ? REAL(1.0) : REAL(-1.0);
for (i=0; i<3; i++) q1[i] += sign[1] * S1 * R[i*4+1];
sign[2] = (dDOT14(normal,R+2) > 0) ? REAL(1.0) : REAL(-1.0);
for (i=0; i<3; i++) q1[i] += sign[2] * S2 * R[i*4+2];
// find the other endpoint q2 of the intersecting edge
dVector3 q2;
for (i=0; i<3; i++)
q2[i] = q1[i] - R[code-4 + i*4] * (sign[code-4] * side[code-4]);
// determine the closest point between the box edge and the line segment
dVector3 cp1,cp2;
dClosestLineSegmentPoints (q1,q2, p1,p2, cp1,cp2);
for (i=0; i<3; i++) contact[0].pos[i] = cp1[i] - REAL(0.5)*normal[i]*depth;
return 1;
}
else {
// handle face contacts.
// @@@ temporary: make deepest vertex on the line the contact point.
// @@@ this kind of works, but we sometimes need two contact points for
// @@@ stability.
// compute 'v' in global coordinates
dVector3 gv;
for (i=0; i<3; i++) gv[i] = p2[i] - p1[i];
if (dDOT (normal,gv) > 0) {
for (i=0; i<3; i++)
contact[0].pos[i] = p1[i] + (depth*REAL(0.5)-radius)*normal[i];
}
else {
for (i=0; i<3; i++)
contact[0].pos[i] = p2[i] + (depth*REAL(0.5)-radius)*normal[i];
}
return 1;
}
}
//***************************************************************************
// this function works, it's just not being used for anything at the moment:
// given a box (R,side), `R' is the rotation matrix for the box, and `side'
// is a vector of x/y/z side lengths, return the size of the interval of the
// box projected along the given axis. if the axis has unit length then the
// return value will be the actual diameter, otherwise the result will be
// scaled by the axis length.
static inline dReal boxDiameter (const dMatrix3 R, const dVector3 side,
const dVector3 axis)
{
dVector3 q;
dMULTIPLY1_331 (q,R,axis); // transform axis to body-relative
return dFabs(q[0])*side[0] + dFabs(q[1])*side[1] + dFabs(q[2])*side[2];
}
//***************************************************************************
// the old capped cylinder to capped cylinder collision code. this fails to
// detect cap-to-cap contact points when the cylinder axis are aligned, but
// other that that it is pretty robust.
// this returns at most one contact point when the two cylinder's axes are not
// aligned, and at most two (for stability) when they are aligned.
// the algorithm minimizes the distance between two "sample spheres" that are
// positioned along the cylinder axes according to:
// sphere1 = pos1 + alpha1 * axis1
// sphere2 = pos2 + alpha2 * axis2
// alpha1 and alpha2 are limited to +/- half the length of the cylinders.
// the algorithm works by finding a solution that has both alphas free, or
// a solution that has one or both alphas fixed to the ends of the cylinder.
int dCollideCCylinderCCylinder (dxGeom *o1, dxGeom *o2,
int flags, dContactGeom *contact, int skip)
{
int i;
const dReal tolerance = REAL(1e-5);
dIASSERT (skip >= (int)sizeof(dContactGeom));
dIASSERT (o1->type == dCCylinderClass);
dIASSERT (o2->type == dCCylinderClass);
dxCCylinder *cyl1 = (dxCCylinder*) o1;
dxCCylinder *cyl2 = (dxCCylinder*) o2;
contact->g1 = o1;
contact->g2 = o2;
// copy out some variables, for convenience
dReal lz1 = cyl1->lz * REAL(0.5);
dReal lz2 = cyl2->lz * REAL(0.5);
dReal *pos1 = o1->pos;
dReal *pos2 = o2->pos;
dReal axis1[3],axis2[3];
axis1[0] = o1->R[2];
axis1[1] = o1->R[6];
axis1[2] = o1->R[10];
axis2[0] = o2->R[2];
axis2[1] = o2->R[6];
axis2[2] = o2->R[10];
dReal alpha1,alpha2,sphere1[3],sphere2[3];
int fix1 = 0; // 0 if alpha1 is free, +/-1 to fix at +/- lz1
int fix2 = 0; // 0 if alpha2 is free, +/-1 to fix at +/- lz2
for (int count=0; count<9; count++) {
// find a trial solution by fixing or not fixing the alphas
if (fix1) {
if (fix2) {
// alpha1 and alpha2 are fixed, so the solution is easy
if (fix1 > 0) alpha1 = lz1; else alpha1 = -lz1;
if (fix2 > 0) alpha2 = lz2; else alpha2 = -lz2;
for (i=0; i<3; i++) sphere1[i] = pos1[i] + alpha1*axis1[i];
for (i=0; i<3; i++) sphere2[i] = pos2[i] + alpha2*axis2[i];
}
else {
// fix alpha1 but let alpha2 be free
if (fix1 > 0) alpha1 = lz1; else alpha1 = -lz1;
for (i=0; i<3; i++) sphere1[i] = pos1[i] + alpha1*axis1[i];
alpha2 = (axis2[0]*(sphere1[0]-pos2[0]) +
axis2[1]*(sphere1[1]-pos2[1]) +
axis2[2]*(sphere1[2]-pos2[2]));
for (i=0; i<3; i++) sphere2[i] = pos2[i] + alpha2*axis2[i];
}
}
else {
if (fix2) {
// fix alpha2 but let alpha1 be free
if (fix2 > 0) alpha2 = lz2; else alpha2 = -lz2;
for (i=0; i<3; i++) sphere2[i] = pos2[i] + alpha2*axis2[i];
alpha1 = (axis1[0]*(sphere2[0]-pos1[0]) +
axis1[1]*(sphere2[1]-pos1[1]) +
axis1[2]*(sphere2[2]-pos1[2]));
for (i=0; i<3; i++) sphere1[i] = pos1[i] + alpha1*axis1[i];
}
else {
// let alpha1 and alpha2 be free
// compute determinant of d(d^2)\d(alpha) jacobian
dReal a1a2 = dDOT (axis1,axis2);
dReal det = REAL(1.0)-a1a2*a1a2;
if (det < tolerance) {
// the cylinder axes (almost) parallel, so we will generate up to two
// contacts. the solution matrix is rank deficient so alpha1 and
// alpha2 are related by:
// alpha2 = alpha1 + (pos1-pos2)'*axis1 (if axis1==axis2)
// or alpha2 = -(alpha1 + (pos1-pos2)'*axis1) (if axis1==-axis2)
// first compute where the two cylinders overlap in alpha1 space:
if (a1a2 < 0) {
axis2[0] = -axis2[0];
axis2[1] = -axis2[1];
axis2[2] = -axis2[2];
}
dReal q[3];
for (i=0; i<3; i++) q[i] = pos1[i]-pos2[i];
dReal k = dDOT (axis1,q);
dReal a1lo = -lz1;
dReal a1hi = lz1;
dReal a2lo = -lz2 - k;
dReal a2hi = lz2 - k;
dReal lo = (a1lo > a2lo) ? a1lo : a2lo;
dReal hi = (a1hi < a2hi) ? a1hi : a2hi;
if (lo <= hi) {
int num_contacts = flags & NUMC_MASK;
if (num_contacts >= 2 && lo < hi) {
// generate up to two contacts. if one of those contacts is
// not made, fall back on the one-contact strategy.
for (i=0; i<3; i++) sphere1[i] = pos1[i] + lo*axis1[i];
for (i=0; i<3; i++) sphere2[i] = pos2[i] + (lo+k)*axis2[i];
int n1 = dCollideSpheres (sphere1,cyl1->radius,
sphere2,cyl2->radius,contact);
if (n1) {
for (i=0; i<3; i++) sphere1[i] = pos1[i] + hi*axis1[i];
for (i=0; i<3; i++) sphere2[i] = pos2[i] + (hi+k)*axis2[i];
dContactGeom *c2 = CONTACT(contact,skip);
int n2 = dCollideSpheres (sphere1,cyl1->radius,
sphere2,cyl2->radius, c2);
if (n2) {
c2->g1 = o1;
c2->g2 = o2;
return 2;
}
}
}
// just one contact to generate, so put it in the middle of
// the range
alpha1 = (lo + hi) * REAL(0.5);
alpha2 = alpha1 + k;
for (i=0; i<3; i++) sphere1[i] = pos1[i] + alpha1*axis1[i];
for (i=0; i<3; i++) sphere2[i] = pos2[i] + alpha2*axis2[i];
return dCollideSpheres (sphere1,cyl1->radius,
sphere2,cyl2->radius,contact);
}
else return 0;
}
det = REAL(1.0)/det;
dReal delta[3];
for (i=0; i<3; i++) delta[i] = pos1[i] - pos2[i];
dReal q1 = dDOT (delta,axis1);
dReal q2 = dDOT (delta,axis2);
alpha1 = det*(a1a2*q2-q1);
alpha2 = det*(q2-a1a2*q1);
for (i=0; i<3; i++) sphere1[i] = pos1[i] + alpha1*axis1[i];
for (i=0; i<3; i++) sphere2[i] = pos2[i] + alpha2*axis2[i];
}
}
// if the alphas are outside their allowed ranges then fix them and
// try again
if (fix1==0) {
if (alpha1 < -lz1) {
fix1 = -1;
continue;
}
if (alpha1 > lz1) {
fix1 = 1;
continue;
}
}
if (fix2==0) {
if (alpha2 < -lz2) {
fix2 = -1;
continue;
}
if (alpha2 > lz2) {
fix2 = 1;
continue;
}
}
// unfix the alpha variables if the local distance gradient indicates
// that we are not yet at the minimum
dReal tmp[3];
for (i=0; i<3; i++) tmp[i] = sphere1[i] - sphere2[i];
if (fix1) {
dReal gradient = dDOT (tmp,axis1);
if ((fix1 > 0 && gradient > 0) || (fix1 < 0 && gradient < 0)) {
fix1 = 0;
continue;
}
}
if (fix2) {
dReal gradient = -dDOT (tmp,axis2);
if ((fix2 > 0 && gradient > 0) || (fix2 < 0 && gradient < 0)) {
fix2 = 0;
continue;
}
}
return dCollideSpheres (sphere1,cyl1->radius,sphere2,cyl2->radius,contact);
}
// if we go through the loop too much, then give up. we should NEVER get to
// this point (i hope).
dMessage (0,"dCollideCC(): too many iterations");
return 0;
}
syntax highlighted by Code2HTML, v. 0.9.1