Replace SdfLib with linear octree interpolation of TriangleMeshDistance.
Temporary changes to the octree: - Changed frame from mesh to geom Before change (tolerance 1e-3): ``` Simulation time : 2.34 s Steps per second : 4275 Realtime factor : 8.55 x Time per step : 233.9 µs Newton iters / step : 2.26 Contacts / step : 3.69 Constraints / step : 14.76 Degrees of freedom : 12 Dynamic memory usage : 0.7% of 14M ``` After change (6 octree levels): ``` Simulation time : 2.24 s Steps per second : 4472 Realtime factor : 8.94 x Time per step : 223.6 µs Newton iters / step : 2.47 Contacts / step : 3.37 Constraints / step : 13.49 Degrees of freedom : 12 Dynamic memory usage : 0.2% of 14M ``` PiperOrigin-RevId: 781019754 Change-Id: Ib15581244dfe9e571e1c6c2cac4a101cf3d8ba3d
This commit is contained in:
Alessio Quaglino
committed by
Copybara-Service
Copybara-Service
parent
e6c5715903
commit
b81f1db8af
@@ -37,7 +37,7 @@ set(MUJOCO_SDF_SRCS
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add_library(sdf_plugin SHARED)
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target_sources(sdf_plugin PRIVATE ${MUJOCO_SDF_SRCS})
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target_include_directories(sdf_plugin PRIVATE ${MUJOCO_SDF_INCLUDE})
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target_link_libraries(sdf_plugin PRIVATE mujoco SdfLib)
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target_link_libraries(sdf_plugin PRIVATE mujoco)
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target_compile_options(
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sdf_plugin
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PRIVATE ${AVX_COMPILE_OPTIONS}
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@@ -66,11 +66,11 @@ Parameters:
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Implemented in [sdflib.cc](sdflib.cc). Example usage in [cow.xml](../../model/plugin/sdf/cow.xml).
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This plugin uses the library [SdfLib](https://github.com/UPC-ViRVIG/SdfLib) to compute a voxel-based approximation of a
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user-specified mesh. The mesh can be arbitrary and not necessarily convex. This offers an alternative to
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convex-decomposed meshes. The performance is likely to be slower than that of analytic SDFs, since a cubic
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approximation has to be evaluated on the convex grid. However, the SDF generation is done automatically, simplifying the
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task of creating an SDF, which can be difficult for complex shapes.
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This plugin uses the library [TriangleMeshDistance](https://github.com/InteractiveComputerGraphics/TriangleMeshDistance)
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to compute a voxel-based approximation of a user-specified mesh. The mesh can be arbitrary and not necessarily convex.
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This offers an alternative to convex-decomposed meshes. The performance is likely to be slower than that of analytic
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SDFs, since a cubic approximation has to be evaluated on the convex grid. However, the SDF generation is done
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automatically, simplifying the task of creating an SDF, which can be difficult for complex shapes.
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### How to make your own SDF
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+138
-46
@@ -13,12 +13,12 @@
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// limitations under the License.
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#include <cstdint>
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#include <cstring>
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#include <optional>
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#include <utility>
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#include <vector>
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#include <SdfLib/utils/Mesh.h>
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#include <SdfLib/OctreeSdf.h>
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#include <TriangleMeshDistance/include/tmd/TriangleMeshDistance.h>
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#include <mujoco/mjplugin.h>
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#include <mujoco/mujoco.h>
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#include "sdf.h"
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@@ -27,38 +27,107 @@
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namespace mujoco::plugin::sdf {
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namespace {
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inline unsigned int* MakeNonConstUnsigned(const int* ptr) {
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return reinterpret_cast<unsigned int*>(const_cast<int*>(ptr));
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}
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mjtNum boxProjection(glm::vec3& point, const sdflib::BoundingBox& box) {
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glm::vec3 r = point - box.getCenter();
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glm::vec3 q = glm::abs(r) - 0.5f * box.getSize();
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mjtNum boxProjection(mjtNum point[3], const mjtNum box[6]) {
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mjtNum r[3] = {point[0] - box[0], point[1] - box[1], point[2] - box[2]};
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mjtNum q[3] = {mju_abs(r[0]) - box[3], mju_abs(r[1]) - box[4],
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mju_abs(r[2]) - box[5]};
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mjtNum dist_sqr = 0;
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mjtNum eps = 1e-6;
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// skip the projection if inside
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if (q.x <= 0 && q.y <= 0 && q.z <= 0) {
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return glm::max(q.x, glm::max(q.y, q.z));
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if (q[0] <= 0 && q[1] <= 0 && q[2] <= 0) {
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return mju_max(q[0], mju_max(q[1], q[2]));
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}
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// in-place projection inside the box if outside
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if ( q.x >= 0 ) {
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dist_sqr += q.x * q.x;
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point.x -= r.x > 0 ? (q.x+eps) : -(q.x+eps);
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if ( q[0] >= 0 ) {
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dist_sqr += q[0] * q[0];
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point[0] -= r[0] > 0 ? (q[0]+eps) : -(q[0]+eps);
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}
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if ( q.y >= 0 ) {
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dist_sqr += q.y * q.y;
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point.y -= r.y > 0 ? (q.y+eps) : -(q.y+eps);
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if ( q[1] >= 0 ) {
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dist_sqr += q[1] * q[1];
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point[1] -= r[1] > 0 ? (q[1]+eps) : -(q[1]+eps);
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}
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if ( q.z >= 0 ) {
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dist_sqr += q.z * q.z;
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point.z -= r.z > 0 ? (q.z+eps) : -(q.z+eps);
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if ( q[2] >= 0 ) {
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dist_sqr += q[2] * q[2];
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point[2] -= r[2] > 0 ? (q[2]+eps) : -(q[2]+eps);
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}
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return mju_sqrt(dist_sqr);
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}
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// find the octree leaf containing the point p, return the index of the leaf and
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// populate the weights of the interpolated function (if w is not null) and of
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// its gradient (if dw is not null) using the vertices as degrees of freedom for
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// trilinear interpolation.
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static int findOct(mjtNum w[8], mjtNum dw[8][3], const mjtNum* oct_aabb,
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const int* oct_child, const mjtNum p[3]) {
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std::vector<int> stack = {0};
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mjtNum eps = 1e-8;
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while (!stack.empty()) {
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int node = stack.back();
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stack.pop_back();
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mjtNum vmin[3], vmax[3];
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if (node == -1) { // SHOULD NOT OCCUR
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mju_error("Invalid node number");
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return -1;
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}
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for (int j = 0; j < 3; j++) {
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vmin[j] = oct_aabb[6*node+j] - oct_aabb[6*node+3+j];
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vmax[j] = oct_aabb[6*node+j] + oct_aabb[6*node+3+j];
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}
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// check if the point is inside the aabb of the octree node
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if (p[0] + eps < vmin[0] || p[0] - eps > vmax[0] ||
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p[1] + eps < vmin[1] || p[1] - eps > vmax[1] ||
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p[2] + eps < vmin[2] || p[2] - eps > vmax[2]) {
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continue;
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}
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mjtNum coord[3] = {(p[0] - vmin[0]) / (vmax[0] - vmin[0]),
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(p[1] - vmin[1]) / (vmax[1] - vmin[1]),
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(p[2] - vmin[2]) / (vmax[2] - vmin[2])};
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// check if the node is a leaf
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if (oct_child[8*node+0] == -1 && oct_child[8*node+1] == -1 &&
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oct_child[8*node+2] == -1 && oct_child[8*node+3] == -1 &&
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oct_child[8*node+4] == -1 && oct_child[8*node+5] == -1 &&
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oct_child[8*node+6] == -1 && oct_child[8*node+7] == -1) {
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for (int j = 0; j < 8; j++) {
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if (w) {
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w[j] = (j & 1 ? coord[0] : 1 - coord[0]) *
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(j & 2 ? coord[1] : 1 - coord[1]) *
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(j & 4 ? coord[2] : 1 - coord[2]);
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}
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if (dw) {
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dw[j][0] = (j & 1 ? 1 : -1) *
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(j & 2 ? coord[1] : 1 - coord[1]) *
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(j & 4 ? coord[2] : 1 - coord[2]);
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dw[j][1] = (j & 1 ? coord[0] : 1 - coord[0]) *
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(j & 2 ? 1 : -1) *
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(j & 4 ? coord[2] : 1 - coord[2]);
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dw[j][2] = (j & 1 ? coord[0] : 1 - coord[0]) *
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(j & 2 ? coord[1] : 1 - coord[1]) *
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(j & 4 ? 1 : -1);
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}
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}
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return node;
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}
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// compute which of 8 children to visit next
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int x = coord[0] < .5 ? 1 : 0;
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int y = coord[1] < .5 ? 1 : 0;
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int z = coord[2] < .5 ? 1 : 0;
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stack.push_back(oct_child[8*node + 4*z + 2*y + x]);
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}
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mju_error("Node not found"); // SHOULD NOT OCCUR
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return -1;
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}
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} // namespace
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// factory function
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@@ -76,30 +145,40 @@ std::optional<SdfLib> SdfLib::Create(const mjModel* m, mjData* d,
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int nface = m->mesh_facenum[meshid];
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int* indices = m->mesh_face + 3*m->mesh_faceadr[meshid];
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float* verts = m->mesh_vert + 3*m->mesh_vertadr[meshid];
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std::vector<glm::vec3> vertices(nvert);
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std::vector<double> vertices(3*nvert);
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for (int i = 0; i < nvert; i++) {
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mjtNum vert[3] = {verts[3*i+0], verts[3*i+1], verts[3*i+2]};
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mju_rotVecQuat(vert, vert, m->mesh_quat + 4*meshid);
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mju_addTo3(vert, m->mesh_pos + 3*meshid);
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vertices[i].x = vert[0];
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vertices[i].y = vert[1];
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vertices[i].z = vert[2];
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vertices[3*i+0] = vert[0];
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vertices[3*i+1] = vert[1];
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vertices[3*i+2] = vert[2];
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}
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sdflib::Mesh mesh(vertices.data(), nvert,
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MakeNonConstUnsigned(indices), 3*nface);
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mesh.computeBoundingBox();
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return SdfLib(std::move(mesh));
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tmd::TriangleMeshDistance mesh(vertices.data(), nvert, indices, nface);
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return SdfLib(mesh, m, meshid);
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}
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// plugin constructor
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SdfLib::SdfLib(sdflib::Mesh&& mesh) {
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sdflib::BoundingBox box = mesh.getBoundingBox();
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const glm::vec3 modelBBsize = box.getSize();
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box.addMargin(
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0.1f * glm::max(glm::max(modelBBsize.x, modelBBsize.y), modelBBsize.z));
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sdf_func_ =
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sdflib::OctreeSdf(mesh, box, 8, 3, 1e-3,
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sdflib::OctreeSdf::InitAlgorithm::CONTINUITY, 1);
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SdfLib::SdfLib(const tmd::TriangleMeshDistance& sdf, const mjModel* m,
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int meshid) {
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// TODO: do not evaluate the SDF multiple times at the same vertex
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// TODO: the value at hanging vertices should be computed from the parent
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int octadr = m->mesh_octadr[meshid];
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int octnum = m->mesh_octnum[meshid];
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oct_aabb_.assign(m->oct_aabb + 6*octadr,
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m->oct_aabb + 6*octadr + 6*octnum);
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oct_child_.assign(m->oct_child + 8 * octadr,
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m->oct_child + 8 * octadr + 8 * octnum);
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for (int i = 0; i < octnum; ++i) {
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for (int j = 0; j < 8; j++) {
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mjtNum v[3];
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v[0] = oct_aabb_[6*i+0] + (j&1 ? 1 : -1) * oct_aabb_[6*i+3];
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v[1] = oct_aabb_[6*i+1] + (j&2 ? 1 : -1) * oct_aabb_[6*i+4];
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v[2] = oct_aabb_[6*i+2] + (j&4 ? 1 : -1) * oct_aabb_[6*i+5];
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sdf_coeff_.push_back(sdf.signed_distance(v).distance);
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}
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}
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mju_copy(box_, m->oct_aabb + 6*octadr, 6);
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}
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// plugin computation
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@@ -120,22 +199,35 @@ void SdfLib::Visualize(const mjModel* m, mjData* d, const mjvOption* opt,
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// sdf
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mjtNum SdfLib::Distance(const mjtNum p[3]) const {
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glm::vec3 point(p[0], p[1], p[2]);
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mjtNum boxDist = boxProjection(point, sdf_func_.getGridBoundingBox());
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return sdf_func_.getDistance(point) + (boxDist <= 0 ? 0 : boxDist);
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mjtNum w[8];
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mjtNum sdf = 0;
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mjtNum point[3] = {p[0], p[1], p[2]};
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mjtNum boxDist = boxProjection(point, box_);
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if (boxDist > 0) {
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return boxDist;
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}
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int node = findOct(w, nullptr, oct_aabb_.data(), oct_child_.data(), point);
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for (int i = 0; i < 8; ++i) {
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sdf += w[i] * sdf_coeff_[8*node + i];
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}
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return sdf;
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}
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// gradient of sdf
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void SdfLib::Gradient(mjtNum grad[3], const mjtNum point[3]) const {
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glm::vec3 gradient;
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glm::vec3 p(point[0], point[1], point[2]);
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mjtNum p[3] = {point[0], point[1], point[2]};
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// analytic in the interior
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if (boxProjection(p, sdf_func_.getGridBoundingBox()) <= 0) {
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sdf_func_.getDistance(p, gradient);
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grad[0] = gradient[0];
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grad[1] = gradient[1];
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grad[2] = gradient[2];
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if (boxProjection(p, box_) <= 0) {
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mjtNum dw[8][3];
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mju_zero3(grad);
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int node = findOct(nullptr, dw, oct_aabb_.data(), oct_child_.data(), p);
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for (int i = 0; i < 8; ++i) {
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grad[0] += dw[i][0] * sdf_coeff_[8*node + i];
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grad[1] += dw[i][1] * sdf_coeff_[8*node + i];
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grad[2] += dw[i][2] * sdf_coeff_[8*node + i];
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}
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return;
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}
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+8
-4
@@ -16,14 +16,14 @@
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#define MUJOCO_PLUGIN_SDF_SDFLIB_H_
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#include <optional>
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#include <vector>
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#include <SdfLib/utils/Mesh.h>
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#include <SdfLib/OctreeSdf.h>
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#include <mujoco/mjdata.h>
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#include <mujoco/mjmodel.h>
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#include <mujoco/mjtnum.h>
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#include <mujoco/mjvisualize.h>
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#include "sdf.h"
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#include <TriangleMeshDistance/include/tmd/TriangleMeshDistance.h>
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namespace mujoco::plugin::sdf {
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class SdfLib {
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@@ -44,9 +44,13 @@ class SdfLib {
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static void RegisterPlugin();
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private:
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SdfLib(sdflib::Mesh&& mesh);
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SdfLib(const tmd::TriangleMeshDistance& sdf, const mjModel* m, int meshid);
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SdfVisualizer visualizer_;
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sdflib::OctreeSdf sdf_func_;
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std::vector<double> sdf_coeff_;
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mjtNum box_[6];
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std::vector<mjtNum> oct_aabb_;
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std::vector<int> oct_child_;
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};
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} // namespace mujoco::plugin::sdf
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