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engine_collision_driver.c
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engine_collision_driver.c
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// Copyright 2021 DeepMind Technologies Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "engine/engine_collision_driver.h"
#include <stddef.h>
#include <string.h>
#include <mujoco/mjdata.h>
#include <mujoco/mjmacro.h>
#include <mujoco/mjmodel.h>
#include "engine/engine_callback.h"
#include "engine/engine_collision_convex.h"
#include "engine/engine_collision_primitive.h"
#include "engine/engine_core_constraint.h"
#include "engine/engine_crossplatform.h"
#include "engine/engine_io.h"
#include "engine/engine_util_blas.h"
#include "engine/engine_util_errmem.h"
#include "engine/engine_util_misc.h"
#include "engine/engine_util_solve.h"
#include "engine/engine_util_spatial.h"
// table of pair-wise collision functions
mjfCollision mjCOLLISIONFUNC[mjNGEOMTYPES][mjNGEOMTYPES] = {
/* PLANE HFIELD SPHERE CAPSULE ELLIPSOID CYLINDER BOX MESH */
/*PLANE */ {0, 0, mjc_PlaneSphere, mjc_PlaneCapsule, mjc_PlaneConvex, mjc_PlaneCylinder, mjc_PlaneBox, mjc_PlaneConvex},
/*HFIELD */ {0, 0, mjc_ConvexHField, mjc_ConvexHField, mjc_ConvexHField, mjc_ConvexHField, mjc_ConvexHField, mjc_ConvexHField},
/*SHPERE */ {0, 0, mjc_SphereSphere, mjc_SphereCapsule, mjc_Convex, mjc_SphereCylinder, mjc_SphereBox, mjc_Convex},
/*CAPSULE */ {0, 0, 0, mjc_CapsuleCapsule, mjc_Convex, mjc_Convex, mjc_CapsuleBox, mjc_Convex},
/*ELLIPSOID */ {0, 0, 0, 0, mjc_Convex, mjc_Convex, mjc_Convex, mjc_Convex},
/*CYLINDER */ {0, 0, 0, 0, 0, mjc_Convex, mjc_Convex, mjc_Convex},
/*BOX */ {0, 0, 0, 0, 0, 0, mjc_BoxBox, mjc_Convex},
/*MESH */ {0, 0, 0, 0, 0, 0, 0, mjc_Convex}
};
//------------------------------------ static functions --------------------------------------------
// plane to geom_center squared distance, g1 is a plane
static mjtNum plane_geom(const mjModel* m, mjData* d, int g1, int g2) {
mjtNum* mat1 = d->geom_xmat + 9*g1;
mjtNum norm[3] = {mat1[2], mat1[5], mat1[8]};
mjtNum dif[3];
mju_sub3(dif, d->geom_xpos + 3*g2, d->geom_xpos + 3*g1);
return mju_dot3(dif, norm);
}
// squared Euclidean distance between 3D vectors
static inline mjtNum squaredDist3(const mjtNum pos1[3], const mjtNum pos2[3]) {
mjtNum dif[3] = {pos1[0]-pos2[0], pos1[1]-pos2[1], pos1[2]-pos2[2]};
return dif[0]*dif[0] + dif[1]*dif[1] + dif[2]*dif[2];
}
// bounding-sphere collision
static int mj_collideSphere(const mjModel* m, mjData* d, int g1, int g2, mjtNum margin) {
// neither geom is a plane
if (m->geom_rbound[g1] > 0 && m->geom_rbound[g2] > 0) {
mjtNum bound = m->geom_rbound[g1] + m->geom_rbound[g2] + margin;
if (squaredDist3(d->geom_xpos+3*g1, d->geom_xpos+3*g2) > bound*bound) {
return 0;
}
}
// one geom is a plane
if (m->geom_type[g1] == mjGEOM_PLANE && m->geom_rbound[g2] > 0
&& plane_geom(m, d, g1, g2) > margin+m->geom_rbound[g2]) {
return 0;
}
if (m->geom_type[g2] == mjGEOM_PLANE && m->geom_rbound[g1] > 0
&& plane_geom(m, d, g2, g1) > margin+m->geom_rbound[g1]) {
return 0;
}
return 1;
}
//------------------------------------ binary tree search ------------------------------------------
// checks if the proposed collision pair is already present in pair_geom and calls narrow phase
void mj_collidePair(const mjModel* m, mjData* d, int g1, int g2, int merged,
int startadr, int pairadr) {
// merged: make sure geom pair is not repeated
if (merged) {
// find matching pair
int found = 0;
for (int k=startadr; k < pairadr; k++) {
if ((m->pair_geom1[k] == g1 && m->pair_geom2[k] == g2) ||
(m->pair_geom1[k] == g2 && m->pair_geom2[k] == g1)) {
found = 1;
break;
}
}
// not found: test
if (!found) {
mj_collideGeoms(m, d, g1, g2, 0, 0);
}
}
// not merged: always test
else {
mj_collideGeoms(m, d, g1, g2, 0, 0);
}
}
// oriented bounding boxes collision (see Gottschalk et al.)
int mj_collideOBB(const mjtNum aabb1[6], const mjtNum aabb2[6],
const mjtNum xpos1[3], const mjtNum xmat1[9],
const mjtNum xpos2[3], const mjtNum xmat2[9],
mjtNum product[36], mjtNum offset[12], mjtByte* initialize) {
// get infinite dimensions (planes only)
mjtByte inf1[3] = {aabb1[3] >= mjMAXVAL, aabb1[4] >= mjMAXVAL, aabb1[5] >= mjMAXVAL};
mjtByte inf2[3] = {aabb2[3] >= mjMAXVAL, aabb2[4] >= mjMAXVAL, aabb2[5] >= mjMAXVAL};
// if a bounding box is infinite, there must be a collision
if ((inf1[0] && inf1[1] && inf1[2]) || (inf2[0] && inf2[1] && inf2[2])) {
return 1;
}
const mjtNum* aabb[2] = {aabb1, aabb2};
const mjtNum *xmat[2] = {xmat1, xmat2};
const mjtNum *xpos[2] = {xpos1, xpos2};
mjtNum xcenter[2][3], normal[2][3][3];
mjtNum proj[2], radius[2];
mjtByte infinite[2] = {inf1[0] || inf1[1] || inf1[2], inf2[0] || inf2[1] || inf2[2]};
// compute centers in local coordinates
if (product == NULL) {
for (int i=0; i < 2; i++) { // bounding boxes
for (int j=0; j < 3; j++) { // axes
mju_rotVecMat(xcenter[i], aabb[i], xmat[i]);
mju_addTo3(xcenter[i], xpos[i]);
}
}
}
// compute normals in global coordinates
for (int i=0; i < 2; i++) { // bounding boxes
for (int j=0; j < 3; j++) { // faces
for (int k=0; k < 3; k++) { // world axes
normal[i][j][k] = xmat[i][3*k+j];
}
}
}
// precompute dot products
if (product && offset && *initialize) {
for (int i=0; i < 2; i++) { // bodies
for (int j=0; j < 2; j++) { // bodies
for (int k=0; k < 3; k++) { // axes
for (int l=0; l < 3; l++) { // axes
product[18*i + 9*j + 3*k + l] = mju_dot3(normal[i][l], normal[j][k]);
}
offset[6*i + 3*j + k] = mju_dot3(xpos[i], normal[j][k]);
}
}
}
*initialize = 0;
}
// check intersections
for (int j=0; j < 2; j++) { // bounding boxes
if (infinite[1-j]) {
continue; // skip test against an infinite body
}
for (int k=0; k < 3; k++) { // face
for (int i=0; i < 2; i++) { // bounding boxes
if (product == NULL) {
proj[i] = mju_dot3(xcenter[i], normal[j][k]);
radius[i] = fabs(aabb[i][3]*mju_dot3(normal[i][0], normal[j][k])) +
fabs(aabb[i][4]*mju_dot3(normal[i][1], normal[j][k])) +
fabs(aabb[i][5]*mju_dot3(normal[i][2], normal[j][k]));
} else {
int adr = 18*i + 9*j + 3*k;
proj[i] = aabb[i][0] * product[adr + 0] +
aabb[i][1] * product[adr + 1] +
aabb[i][2] * product[adr + 2] +
offset[6*i + 3*j + k];
radius[i] = fabs(aabb[i][3]*product[adr + 0]) +
fabs(aabb[i][4]*product[adr + 1]) +
fabs(aabb[i][5]*product[adr + 2]);
}
}
if (radius[0]+radius[1] < fabs(proj[1]-proj[0])) {
return 0;
}
}
}
return 1;
}
static mjCollisionTree* mj_stackAllocTree(mjData* d, int max_stack) {
// check that the quotient is an integer
_Static_assert(sizeof(mjCollisionTree*) % sizeof(mjtNum) == 0,
"mjCollisionTree has a different size from mjtNum");
return (mjCollisionTree*)mj_stackAlloc(
d, max_stack * sizeof(mjCollisionTree*) / sizeof(mjtNum));
}
// binary search between two body trees
void mj_collideTree(const mjModel* m, mjData* d, int b1, int b2,
int merged, int startadr, int pairadr) {
const int bvhadr1 = m->body_bvhadr[b1];
const int bvhadr2 = m->body_bvhadr[b2];
const mjtNum* bvh1 = m->bvh_aabb + 6 * bvhadr1;
const mjtNum* bvh2 = m->bvh_aabb + 6 * bvhadr2;
const int* child1 = m->bvh_child + 2 * bvhadr1;
const int* child2 = m->bvh_child + 2 * bvhadr2;
mjtNum product[36]; // 2 bb x 2 bb x 3 axes (body) x 3 axes (world)
mjtNum offset[12]; // 2 bb x 2 bb x 3 axes (world)
mjtByte initialize = 1;
mjMARKSTACK;
// TODO(b/273737633): Store bvh max depths to make this bound tighter.
const int max_stack = m->body_bvhnum[b1] + m->body_bvhnum[b2];
mjCollisionTree* stack = mj_stackAllocTree(d, max_stack);
int nstack = 1;
stack[0].node1 = stack[0].node2 = 0;
while (nstack) {
// pop from stack
nstack--;
int node1 = stack[nstack].node1;
int node2 = stack[nstack].node2;
mjtByte isleaf1 = (child1[2*node1] == -1) && (child1[2*node1+1] == -1);
mjtByte isleaf2 = (child2[2*node2] == -1) && (child2[2*node2+1] == -1);
int nodeid1 = m->bvh_geomid[bvhadr1 + node1];
int nodeid2 = m->bvh_geomid[bvhadr2 + node2];
// both are leaves
if (isleaf1 && isleaf2 && nodeid1 != -1 && nodeid2 != -1) {
if (mj_collideSphere(m, d, nodeid1, nodeid2, /*margin=*/ 0)) {
if (mj_collideOBB(m->geom_aabb + 6*nodeid1, m->geom_aabb + 6*nodeid2,
d->geom_xpos + 3*nodeid1, d->geom_xmat + 9*nodeid1,
d->geom_xpos + 3*nodeid2, d->geom_xmat + 9*nodeid2,
NULL, NULL, &initialize)) {
mj_collidePair(m, d, nodeid1, nodeid2, merged, startadr, pairadr);
d->bvh_active[node1 + bvhadr1] = 1;
d->bvh_active[node2 + bvhadr2] = 1;
}
}
continue;
}
// if no intersection at intermediate levels, stop
if (!mj_collideOBB(bvh1 + 6*node1, bvh2 + 6*node2,
d->xipos + 3*b1, d->ximat + 9*b1,
d->xipos + 3*b2, d->ximat + 9*b2,
product, offset, &initialize)) {
continue;
}
d->bvh_active[node1 + bvhadr1] = 1;
d->bvh_active[node2 + bvhadr2] = 1;
// keep traversing the tree
if (!isleaf1 && isleaf2) {
for (int i=0; i < 2; i++) {
if (child1[2*node1+i] != -1) {
if (nstack >= max_stack) {
mjERROR("BVH stack depth exceeded."); // SHOULD NOT OCCUR
}
stack[nstack].node1 = child1[2*node1+i];
stack[nstack].node2 = node2;
nstack++;
}
}
} else if (isleaf1 && !isleaf2) {
for (int i=0; i < 2; i++) {
if (child2[2*node2+i] != -1) {
if (nstack >= max_stack) {
mjERROR("BVH stack depth exceeded."); // SHOULD NOT OCCUR
}
stack[nstack].node1 = node1;
stack[nstack].node2 = child2[2*node2+i];
nstack++;
}
}
} else {
// compute surface areas of bounding boxes
mjtNum x1 = bvh1[6*node1+3]-bvh1[6*node1+0];
mjtNum y1 = bvh1[6*node1+4]-bvh1[6*node1+1];
mjtNum z1 = bvh1[6*node1+5]-bvh1[6*node1+2];
mjtNum x2 = bvh2[6*node2+3]-bvh2[6*node2+0];
mjtNum y2 = bvh2[6*node2+4]-bvh2[6*node2+1];
mjtNum z2 = bvh2[6*node2+5]-bvh2[6*node2+2];
mjtNum surface1 = x1*y1 + y1*z1 + z1*x1;
mjtNum surface2 = x2*y2 + y2*z2 + z2*x2;
// traverse the hierarchy whose bounding box has the larger surface area
if (surface1 > surface2) {
for (int i = 0; i < 2; i++) {
if (child1[2 * node1 + i] != -1) {
if (nstack >= max_stack) {
mjERROR("BVH stack depth exceeded."); // SHOULD NOT OCCUR
}
stack[nstack].node1 = child1[2 * node1 + i];
stack[nstack].node2 = node2;
nstack++;
}
}
} else {
for (int i = 0; i < 2; i++) {
if (child2[2 * node2 + i] != -1) {
if (nstack >= max_stack) {
mjERROR("BVH stack depth exceeded."); // SHOULD NOT OCCUR
}
stack[nstack].node1 = node1;
stack[nstack].node2 = child2[2*node2+i];
nstack++;
}
}
}
}
}
mjFREESTACK;
}
//----------------------------- collision detection entry point ------------------------------------
// compare contact pairs by their geom IDs
quicksortfunc(contactcompare, context, el1, el2) {
const mjModel* m = (const mjModel*) context;
mjContact* con1 = (mjContact*)el1;
mjContact* con2 = (mjContact*)el2;
// reproduce the order contacts without mj_collideTree
// normally sorted by (g1, g2), but in mj_collideGeoms, g1 and g2 are swapped based on geom_type.
// here we undo this swapping for the purpose of sorting - needs to be done for each mjContact
int con1_g1 = con1->geom1;
int con1_g2 = con1->geom2;
if (m->geom_type[con1_g1] > m->geom_type[con1_g2]) {
int tmp = con1_g1;
con1_g1 = con1_g2;
con1_g2 = tmp;
}
int con2_g1 = con2->geom1;
int con2_g2 = con2->geom2;
if (m->geom_type[con2_g1] > m->geom_type[con2_g2]) {
int tmp = con2_g1;
con2_g1 = con2_g2;
con2_g2 = tmp;
}
if (con1_g1 < con2_g1) return -1;
if (con1_g1 > con2_g1) return 1;
if (con1_g2 < con2_g2) return -1;
if (con1_g2 > con2_g2) return 1;
return 0;
}
void mj_collision(const mjModel* m, mjData* d) {
int g1, g2, merged, b1 = 0, b2 = 0, exadr = 0, pairadr = 0, startadr;
int nexclude = m->nexclude, npair = m->npair, nbodypair = ((m->nbody-1)*m->nbody)/2;
int *broadphasepair = 0;
mjMARKSTACK;
// reset the size of the contact array
d->ncon = 0;
// reset diagnostics
d->nbodypair_broad = 0;
d->nbodypair_narrow = 0;
d->ngeompair_mid = 0;
d->ngeompair_narrow = 0;
// reset the visualization flags
memset(d->bvh_active, 0, m->nbvh);
// return if disabled
if (mjDISABLED(mjDSBL_CONSTRAINT) || mjDISABLED(mjDSBL_CONTACT)
|| m->nconmax == 0 || m->nbody < 2) {
return;
}
// predefined only; ignore exclude
if (m->opt.collision == mjCOL_PAIR) {
d->nbodypair_broad = npair;
for (pairadr=0; pairadr < npair; pairadr++) {
int ngeompair_narrow_before = d->ngeompair_narrow;
int ngeompair_mid_before = d->ngeompair_mid;
mj_collideGeoms(m, d, pairadr, -1, 0, 0);
if (d->ngeompair_narrow > ngeompair_narrow_before) d->nbodypair_narrow++;
if (d->ngeompair_mid > ngeompair_mid_before) d->nbodypair_broad++;
}
}
// dynamic only or merge; apply exclude
else {
// call broadphase collision detector
int npairs = (m->nbody*(m->nbody - 1))/2;
broadphasepair = mj_stackAllocInt(d, npairs);
nbodypair = mj_broadphase(m, d, broadphasepair, npairs);
unsigned int last_signature = -1;
// loop over body pairs (broadphase or all)
for (int i=0; i < nbodypair; i++) {
// reconstruct body pair ids
b1 = (broadphasepair[i]>>16) & 0xFFFF;
b2 = broadphasepair[i] & 0xFFFF;
// compute signature for this body pair
unsigned int signature = ((b1+1)<<16) + (b2+1);
// pairs come sorted by signature, but may not be unique
// if signature is repeated, skip it
if (signature == last_signature) {
continue;
}
last_signature = signature;
// merge predefined pairs
merged = 0;
startadr = pairadr;
if (npair && m->opt.collision == mjCOL_ALL) {
// test all predefined pairs for which pair_signature<=signature
while (pairadr < npair && m->pair_signature[pairadr] <= signature) {
if (m->pair_signature[pairadr] == signature) {
merged = 1;
}
mj_collideGeoms(m, d, pairadr++, -1, 0, 0);
}
}
// handle exclusion
if (nexclude) {
// advance exadr while exclude_signature < signature
while (exadr < nexclude && m->exclude_signature[exadr] < signature) {
exadr++;
}
// skip this body pair if its signature is found in exclude array
if (exadr < nexclude && m->exclude_signature[exadr] == signature) {
continue;
}
}
int ngeompair_narrow_before = d->ngeompair_narrow;
int ngeompair_mid_before = d->ngeompair_mid;
// test all geom pairs within this body pair
if (m->body_geomnum[b1] && m->body_geomnum[b2]) {
if (!mjDISABLED(mjDSBL_MIDPHASE) && m->body_geomnum[b1]*m->body_geomnum[b2] > 1) {
int ncon_before = d->ncon;
mj_collideTree(m, d, b1, b2, merged, startadr, pairadr);
int ncon_after = d->ncon;
void* context = (void*) m;
mjQUICKSORT(d->contact + ncon_before, ncon_after - ncon_before,
sizeof(mjContact), contactcompare, context);
} else {
for (g1=m->body_geomadr[b1]; g1 < m->body_geomadr[b1]+m->body_geomnum[b1]; g1++) {
for (g2=m->body_geomadr[b2]; g2 < m->body_geomadr[b2]+m->body_geomnum[b2]; g2++) {
mj_collidePair(m, d, g1, g2, merged, startadr, pairadr);
}
}
}
}
if (d->ngeompair_narrow > ngeompair_narrow_before) d->nbodypair_narrow++;
if (d->ngeompair_mid > ngeompair_mid_before) d->nbodypair_broad++;
}
// finish merging predefined pairs
if (npair && m->opt.collision == mjCOL_ALL) {
while (pairadr < npair) {
mj_collideGeoms(m, d, pairadr++, -1, 0, 0);
}
}
}
mjFREESTACK;
}
//----------------------------- broad-phase collision detection ------------------------------------
// helper structure for SAP sorting
struct _mjtBroadphase {
float value;
int body_ismax;
};
typedef struct _mjtBroadphase mjtBroadphase;
// make AABB for one body
static void makeAABB(const mjModel* m, mjData* d, mjtNum* aabb, int body, const mjtNum* frame) {
int geom;
mjtNum _aabb[6], cen;
// no geoms attached to body: set to 0
if (m->body_geomnum[body] == 0) {
mju_zero(aabb, 6);
return;
}
// process all body geoms
for (int i=0; i < m->body_geomnum[body]; i++) {
// get geom id
geom = m->body_geomadr[body]+i;
// set _aabb for this geom
for (int j=0; j < 3; j++) {
cen = mju_dot3(d->geom_xpos+3*geom, frame+3*j);
_aabb[2*j] = cen - m->geom_rbound[geom] - m->geom_margin[geom];
_aabb[2*j+1] = cen + m->geom_rbound[geom] + m->geom_margin[geom];
}
// update body aabb
if (i == 0) {
mju_copy(aabb, _aabb, 6);
} else {
for (int j=0; j < 3; j++) {
aabb[2*j] = mju_min(aabb[2*j], _aabb[2*j]);
aabb[2*j+1] = mju_max(aabb[2*j+1], _aabb[2*j+1]);
}
}
}
}
// return 1 if body has plane or hfield geom, 0 otherwise
static int has_plane_or_hfield(const mjModel* m, int body) {
int start = m->body_geomadr[body];
int end = m->body_geomadr[body] + m->body_geomnum[body];
// scan geoms belonging to body
int g;
for (g=start; g < end; g++) {
if (m->geom_type[g] == mjGEOM_PLANE || m->geom_type[g] == mjGEOM_HFIELD) {
return 1;
}
}
return 0;
}
// filter body pair: 1- discard, 0- proceed
static int body_pair_filter(int weldbody1, int weldparent1, int weldbody2,
int weldparent2, int dsbl_filterparent) {
// same weldbody check
if (weldbody1 == weldbody2) {
return 1;
}
// weldparent check
if ((!dsbl_filterparent && weldbody1 != 0 && weldbody2 != 0) &&
(weldbody1 == weldparent2 || weldbody2 == weldparent1)) {
return 1;
}
// all tests passed
return 0;
}
// add body pair in buffer
static void add_pair(const mjModel* m, int b1, int b2, int* npair, int* pair, int maxpair) {
// add pair if there is room in buffer
if ((*npair) < maxpair) {
// exlude based on contype and conaffinity
if (m && m->body_geomnum[b1] == 1 && m->body_geomnum[b2] == 1) {
// get contypes and conaffinities
int contype1 = m->geom_contype[m->body_geomadr[b1]];
int conaffinity1 = m->geom_conaffinity[m->body_geomadr[b1]];
int contype2 = m->geom_contype[m->body_geomadr[b2]];
int conaffinity2 = m->geom_conaffinity[m->body_geomadr[b2]];
// compatibility check
if (!(contype1 & conaffinity2) && !(contype2 & conaffinity1)) {
return;
}
}
// add pair
if (b1 < b2) {
pair[*npair] = (b1<<16) + b2;
} else {
pair[*npair] = (b2<<16) + b1;
}
(*npair)++;
} else {
mjERROR("broadphase buffer full");
}
}
// comparison function for broadphase
quicksortfunc(broadcompare, context, el1, el2) {
mjtBroadphase* b1 = (mjtBroadphase*)el1;
mjtBroadphase* b2 = (mjtBroadphase*)el2;
if (b1->value < b2->value) {
return -1;
} else if (b1->value == b2->value) {
return 0;
} else {
return 1;
}
}
// comparison function for pair sorting
quicksortfunc(paircompare, context, el1, el2) {
int signature1 = *(int*)el1;
int signature2 = *(int*)el2;
if (signature1 < signature2) {
return -1;
} else if (signature1 == signature2) {
return 0;
} else {
return 1;
}
}
// does body have collidable geoms
static int can_collide(const mjModel* m, int b) {
int g;
// scan geoms; return if collidable
for (g=0; g < m->body_geomnum[b]; g++) {
int ind = m->body_geomadr[b] + g;
if (m->geom_contype[ind] || m->geom_conaffinity[ind]) {
return 1;
}
}
// none found
return 0;
}
// broadphase collision detector
int mj_broadphase(const mjModel* m, mjData* d, int* pair, int maxpair) {
int b1, b2, toremove, cnt, npair = 0, nbody = m->nbody, ngeom = m->ngeom;
mjtNum cov[9], cen[3], dif[3], eigval[3], frame[9], quat[4];
mjtBroadphase *sortbuf, *activebuf;
mjtNum *aabb;
mjMARKSTACK;
int dsbl_filterparent = mjDISABLED(mjDSBL_FILTERPARENT);
// world with geoms, and body with plane or hfield, can collide all bodies
for (b1=0; b1 < nbody; b1++) {
// cannot colide
if (!can_collide(m, b1)) {
continue;
}
// world with geoms, or welded body with plane or hfield
if ((b1 == 0 && m->body_geomnum[b1] > 0) ||
(m->body_weldid[b1] == 0 && has_plane_or_hfield(m, b1))) {
int weld1 = 0;
int parent_weld1 = 0;
for (b2=0; b2 < nbody; b2++) {
int weld2 = m->body_weldid[b2];
int parent_weld2 = m->body_weldid[m->body_parentid[weld2]];
if (!body_pair_filter(weld1, parent_weld1, weld2, parent_weld2,
dsbl_filterparent)) {
add_pair(NULL, b1, b2, &npair, pair, maxpair);
}
}
}
}
// find center of non-world geoms; return if none
cnt = 0;
mju_zero3(cen);
for (int i=0; i < ngeom; i++) {
if (m->geom_bodyid[i]) {
mju_addTo3(cen, d->geom_xpos+3*i);
cnt++;
}
}
if (cnt == 0) {
return npair;
} else {
for (int i=0; i < 3; i++) {
cen[i] /= cnt;
}
}
// compute covariance
mju_zero(cov, 9);
for (int i=0; i < ngeom; i++) {
if (m->geom_bodyid[i]) {
mju_sub3(dif, d->geom_xpos+3*i, cen);
mjtNum D00 = dif[0]*dif[0];
mjtNum D01 = dif[0]*dif[1];
mjtNum D02 = dif[0]*dif[2];
mjtNum D11 = dif[1]*dif[1];
mjtNum D12 = dif[1]*dif[2];
mjtNum D22 = dif[2]*dif[2];
cov[0] += D00;
cov[1] += D01;
cov[2] += D02;
cov[3] += D01;
cov[4] += D11;
cov[5] += D12;
cov[6] += D02;
cov[7] += D12;
cov[8] += D22;
}
}
for (int i=0; i < 9; i++) {
cov[i] /= cnt;
}
// construct covariance-aligned 3D frame
mju_eig3(eigval, frame, quat, cov);
// allocate AABB; clear world entry (not used)
aabb = mj_stackAlloc(d, 6*nbody);
mju_zero(aabb, 6);
// construct body AABB for the aligned frame, count collidable
int bufcnt = 0;
for (int i=1; i < nbody; i++) {
makeAABB(m, d, aabb+6*i, i, frame);
if (can_collide(m, i)) {
bufcnt++;
}
}
// nothing collidable
if (!bufcnt) {
goto endbroad;
}
// allocate sort buffer
int quot = sizeof(mjtBroadphase)/sizeof(mjtNum);
int rem = sizeof(mjtBroadphase)%sizeof(mjtNum);
sortbuf = (mjtBroadphase*)mj_stackAlloc(d, 2*bufcnt*(quot + (rem ? 1 : 0)));
activebuf = (mjtBroadphase*)mj_stackAlloc(d, 2*bufcnt*(quot + (rem ? 1 : 0)));
// init sortbuf with axis0
int k = 0;
for (int i=1; i < nbody; i++) {
// cannot colide
if (!can_collide(m, i)) {
continue;
}
// init
sortbuf[2*k].body_ismax = i;
sortbuf[2*k].value = (float)aabb[6*i];
sortbuf[2*k+1].body_ismax = i + 0x10000;
sortbuf[2*k+1].value = (float)aabb[6*i+1];
k++;
}
// sanity check; SHOULD NOT OCCUR
if (k != bufcnt) {
mjERROR("internal error: unexpected bufcnt");
}
// sort along axis0
mjQUICKSORT(sortbuf, 2*bufcnt, sizeof(mjtBroadphase), broadcompare, 0);
// sweep and prune
cnt = 0; // size of active list
for (int i=0; i < 2*bufcnt; i++) {
// min value: collide with all in list, add
if (!(sortbuf[i].body_ismax & 0x10000)) {
for (int j=0; j < cnt; j++) {
// get body ids: no need to mask ismax because activebuf entries never have the ismax bit,
// and sortbuf[i].body_ismax is tested above
b1 = activebuf[j].body_ismax;
b2 = sortbuf[i].body_ismax;
int weld1 = m->body_weldid[b1];
int weld2 = m->body_weldid[b2];
int parent_weld1 = m->body_weldid[m->body_parentid[weld1]];
int parent_weld2 = m->body_weldid[m->body_parentid[weld2]];
if (body_pair_filter(weld1, parent_weld1, weld2, parent_weld2,
dsbl_filterparent)) {
continue;
}
// use the other two axes to prune if possible
if (aabb[6*b1+2] > aabb[6*b2+3] ||
aabb[6*b1+3] < aabb[6*b2+2] ||
aabb[6*b1+4] > aabb[6*b2+5] ||
aabb[6*b1+5] < aabb[6*b2+4]) {
continue;
}
// add body pair if there is room in buffer
add_pair(m, b1, b2, &npair, pair, maxpair);
}
// add to list
activebuf[cnt] = sortbuf[i];
cnt++;
}
// max value: remove corresponding min value from list
else {
toremove = sortbuf[i].body_ismax & 0xFFFF;
for (int j=0; j < cnt; j++) {
if (activebuf[j].body_ismax == toremove) {
if (j < cnt-1) {
memmove(activebuf+j, activebuf+j+1, sizeof(mjtBroadphase)*(cnt-1-j));
}
cnt--;
break;
}
}
}
}
endbroad:
// sort pairs by signature
if (npair) {
mjQUICKSORT(pair, npair, sizeof(int), paircompare, 0);
}
mjFREESTACK;
return npair;
}
//----------------------------- narrow-phase collision detection -----------------------------------
// test two geoms for collision, apply filters, add to contact list
// flg_user disables filters and uses usermargin
void mj_collideGeoms(const mjModel* m, mjData* d, int g1, int g2, int flg_user, mjtNum usermargin) {
int num, type1, type2, condim;
mjtNum margin, gap, mix, friction[5], solref[mjNREF], solimp[mjNIMP];
mjtNum solreffriction[mjNREF] = {0};
mjContact con[mjMAXCONPAIR];
int ipair = (g2 < 0 ? g1 : -1);
// get explicit geom ids from pair
if (ipair >= 0) {
g1 = m->pair_geom1[ipair];
g2 = m->pair_geom2[ipair];
}
// order geoms by type
if (m->geom_type[g1] > m->geom_type[g2]) {
int i = g1;
g1 = g2;
g2 = i;
}
// copy types and bodies
type1 = m->geom_type[g1];
type2 = m->geom_type[g2];
// return if no collision function
if (!mjCOLLISIONFUNC[type1][type2]) {
return;
}
// apply filters if not predefined pair and not flg_user
if (ipair < 0 && !flg_user) {
// user filter if defined
if (mjcb_contactfilter) {
if (mjcb_contactfilter(m, d, g1, g2)) {
return;
}
}
// otherwise built-in filter
else if (mj_contactFilter(m->geom_contype[g1], m->geom_conaffinity[g1],
m->geom_contype[g2], m->geom_conaffinity[g2])) {
return;
}
}
// set margin, gap, condim: dynamic
if (ipair < 0) {
// margin and gap: max
margin = mju_max(m->geom_margin[g1], m->geom_margin[g2]);
gap = mju_max(m->geom_gap[g1], m->geom_gap[g2]);
// condim: priority or max
if (m->geom_priority[g1] != m->geom_priority[g2]) {
int gp = (m->geom_priority[g1] > m->geom_priority[g2] ? g1 : g2);
condim = m->geom_condim[gp];
} else {
condim = mjMAX(m->geom_condim[g1], m->geom_condim[g2]);
}
}
// set margin, gap, condim: pair
else {
margin = m->pair_margin[ipair];
gap = m->pair_gap[ipair];
condim = m->pair_dim[ipair];
}
// adjust margin
if (flg_user) {
margin = usermargin;
} else {
margin = mj_assignMargin(m, margin);
}
// bounding sphere filter
if (!mj_collideSphere(m, d, g1, g2, margin)) {
return;
}
// increment counter of expected collisions
d->ngeompair_mid++;
// call collision detector to generate contacts
num = mjCOLLISIONFUNC[type1][type2](m, d, con, g1, g2, margin);
// no contacts from near-phase
if (!num) {
return;
}
// increment counter of actual collisions
d->ngeompair_narrow++;
// check number of contacts, SHOULD NOT OCCUR
if (num > mjMAXCONPAIR) {
mjERROR("too many contacts returned by collision function");
}
// remove repeated contacts in box-box
if (type1 == mjGEOM_BOX && type2 == mjGEOM_BOX) {
// use dim field to mark: -1: bad, 0: good
for (int i=0; i < num; i++) {
con[i].dim = 0;
}
// find bad
for (int i=0; i < num-1; i++) {
for (int j=i+1; j < num; j++) {
if (con[i].pos[0] == con[j].pos[0] &&
con[i].pos[1] == con[j].pos[1] &&
con[i].pos[2] == con[j].pos[2]) {
con[i].dim = -1;
break;
}
}
}
// consolidate good
int i = 0;
for (int j=0; j < num; j++) {
if (con[j].dim == 0) {
// different: copy
if (i < j) {
con[i] = con[j];
}
// advance either way
i++;
}
}
// adjust size
num = i;
}
// set friction, solref, solimp: dynamic
if (ipair < 0) {
// different priority
if (m->geom_priority[g1] != m->geom_priority[g2]) {
int gp = (m->geom_priority[g1] > m->geom_priority[g2] ? g1 : g2);
// friction
for (int i=0; i < 3; i++) {
friction[2*i] = m->geom_friction[3*gp+i];
}