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Fix early termination in GJK. It's possible for x_k to be the origin, so we should run the previous test to conclude that the objects are colliding.

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PiperOrigin-RevId: 673834101
Change-Id: I596b30d2847670261f8067840b34dc13de401ecb
This commit is contained in:
Kyle Bayes
2024-09-12 07:16:38 -07:00
committed by Copybara-Service
parent e3d3a24b36
commit 8d165d5cc7
2 changed files with 18 additions and 15 deletions
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src/engine/engine_collision_gjk.c
+8 -7
View File
@@ -141,11 +141,6 @@ static mjtNum gjk(mjCCDStatus* status, mjCCDObj* obj1, mjCCDObj* obj2) {
gjkSupport(s1, s2, obj1, obj2, x_k);
mju_sub3(s_k, s1, s2);
// return early if geom distance isn't needed
if (!get_dist && mju_dot3(x_k, s_k) > 0) {
return mjMAXVAL;
}
// the stopping criteria relies on the Frank-Wolfe duality gap given by
// |f(x_k) - f(x_min)|^2 <= < grad f(x_k), (x_k - s_k) >
mjtNum diff[3];
@@ -154,6 +149,12 @@ static mjtNum gjk(mjCCDStatus* status, mjCCDObj* obj1, mjCCDObj* obj2) {
break;
}
// check if hyperplane is separating the Minkowski difference and the origin;
// if so the objects don't collide, so return early if geom distance isn't needed
if (!get_dist && mju_dot3(x_k, s_k) > 0) {
return mjMAXVAL;
}
// TODO(kylebayes): signedVolume has been written to assume the first vertex is the latest
// support to be added. Once the logic has been updated, then this hack should be removed.
for (int i = n; i > 0; i--) {
@@ -1165,8 +1166,8 @@ mjtNum mjc_ccd(const mjCCDConfig* config, mjCCDStatus* status, mjCCDObj* obj1, m
} else {
dist = 0;
}
mju_free(pt.faces);
mju_free(pt.verts);
free(pt.faces);
free(pt.verts);
}
return dist;
}
test/engine/engine_collision_gjk_test.cc
+10 -8
View File
@@ -101,10 +101,11 @@ int PenetrationWrapper(mjCCDObj* obj1, mjCCDObj* obj2, const ccd_t* ccd,
}
mjtNum Penetration(mjModel* m, mjData* d, int g1, int g2,
mjtNum dir[3] = nullptr, mjtNum pos[3] = nullptr) {
mjCCDObj obj1 = {m, d, g1, -1, -1, -1, -1, 0, {1, 0, 0, 0}, mjc_center,
mjtNum dir[3] = nullptr, mjtNum pos[3] = nullptr,
mjtNum margin = 0) {
mjCCDObj obj1 = {m, d, g1, -1, -1, -1, -1, margin, {1, 0, 0, 0}, mjc_center,
mjc_support};
mjCCDObj obj2 = {m, d, g2, -1, -1, -1, -1, 0, {1, 0, 0, 0}, mjc_center,
mjCCDObj obj2 = {m, d, g2, -1, -1, -1, -1, margin, {1, 0, 0, 0}, mjc_center,
mjc_support};
ccd_t ccd;
// CCD_INIT(&ccd); // uncomment to run ccdMPRPenetration
@@ -120,7 +121,8 @@ mjtNum Penetration(mjModel* m, mjData* d, int g1, int g2,
ccd_vec3_t ccd_dir, ccd_pos;
int ret = PenetrationWrapper(&obj1, &obj2, &ccd, &depth, &ccd_dir, &ccd_pos);
if (ret) return 0; // objects not colliding
// objects not colliding, return max value as geom distance was never computed
if (ret) return mjMAXVAL;
if (dir) mju_copy3(dir, ccd_dir.v);
if (pos) mju_copy3(pos, ccd_pos.v);
return -depth;
@@ -216,8 +218,8 @@ TEST_F(MjGjkTest, EllipsoidEllipsoidIntersect) {
static constexpr char xml[] = R"(
<mujoco>
<worldbody>
<geom name="geom1" type="ellipsoid" pos="1.5 0 -.5" size="2.25 4.5 3"/>
<geom name="geom2" type="ellipsoid" pos="1.5 .5 .5" size="1.5 1.5 2.25"/>
<geom name="geom1" type="ellipsoid" pos="1.5 0 -.5" size=".15 .30 .20"/>
<geom name="geom2" type="ellipsoid" pos="1.5 .5 .5" size=".10 .10 .15"/>
</worldbody>
</mujoco>)";
@@ -230,9 +232,9 @@ TEST_F(MjGjkTest, EllipsoidEllipsoidIntersect) {
int geom1 = mj_name2id(model, mjOBJ_GEOM, "geom1");
int geom2 = mj_name2id(model, mjOBJ_GEOM, "geom2");
mjtNum dist = GeomDist(model, data, geom1, geom2, nullptr, nullptr);
mjtNum dist = Penetration(model, data, geom1, geom2, nullptr, nullptr, 15);
EXPECT_NEAR(dist, 0, kTolerance);
EXPECT_LT(dist, 0);
mj_deleteData(data);
mj_deleteModel(model);
}