https://www.youtube.com/watch?v=PdSdrqhSiZA
The new geom attribute surfacevel (6 numbers: linear and angular velocity in the geom's local frame, angular about the geom frame origin) specifies the velocity of the geom's surface material relative to the geom frame. The relative surface velocity of the two geoms is added to the tangential contact rows of efc_vel in mj_referenceConstraint, so friction drives touching bodies toward the motion of the surface: objects on a conveyor are transported at belt speed, turntables impart omega x r with torsional spin-up for condim >= 4, and surface velocities compose with each other and with body motion. The component along the contact normal is projected out: probe experiments showed that velocity-space emission chatters mass-independently and ingestion merely deepens penetration; normal-direction effects belong to force-space features.
surfacevel is interpreted in the geom frame as authored: for mesh geoms, whose compiled frame absorbs the mesh centering and principal-axes transform, the compiler re-expresses the authored value in the compiled frame.
No special interaction with sleeping: objects being transported do not fall asleep because they are moving; objects at rest on an active surface may sleep like any other resting object.
Includes showcase models (model/surfacevel/): a luggage carousel whose ring is a spinning square-profile supertorus fed by a cascade of belts with matched spinning end rollers, bags dropping in and circulating indefinitely; and a treadmill with a passive humanoid.
PiperOrigin-RevId: 948647785
Change-Id: I0c6559a91cc7ece1237eb8ac2e51986e7342d962
An actuator now owns a block of consecutive controls
(actuator_ctrladr/ctrlnum, width defined by the actuator type) and a block
of consecutive force outputs (actuator_outadr/outnum, width defined by the
transmission type). Force outputs are the scalars of actuation space: one
force, length, velocity and moment row each. nout = dim(actuator_force) is
derived from transmission types; all current types have width 1, so all
three counts coincide for every existing model and behavior is bit-exact.
Array re-keying: ctrlrange/ctrllimited by nu; forcerange/forcelimited/gear/
acc0/length0/lengthrange and the moment row structure by nout; everything
else per actuator. The mjModel actuator block is re-sorted by size key.
Layout-breaking, not behavior-breaking: saved .mjb files are invalidated
(size list changed) and recompilation is required.
PiperOrigin-RevId: 948351772
Change-Id: Icbc196ffa083cb1eaa6f1a3710869c89d8f62540
Previously shell mode required cellcount=1 along at least one axis. This CL
adds support for cellcount > 1 in all three axes by pinning interior grid nodes
to the parent body and reconstructing their positions from boundary nodes via
Transfinite Interpolation (TFI).
PiperOrigin-RevId: 924314800
Change-Id: I8c2438f4866dd4133feed65f535a1ab69f0c9188
Do not allow a mix of `elastic2d != none` with `dof = trilinear` since the latter assumes 3d elasticity.
Also, do not assume that `flex_interp > 0` in the engine. This will enable to use, e.g., `flex_interp = -1` to mean a linear surface finite element instead of a 3d finite element which is currently identified with `flex_interp = 1`.
PiperOrigin-RevId: 903852035
Change-Id: Ia6290b4a05e9e510ffb7f36d141cd525b40d3110
This change introduces an optimization for flexcomp objects defined by a mesh. It identifies grid cells that do not contain any mesh vertices and marks them as empty. Nodes that are exclusively part of empty cells are pinned, preventing them from moving. Stiffness computations are skipped for empty cells, reducing computational cost. The total mass is now distributed only among the non-pinned nodes.
PiperOrigin-RevId: 902565735
Change-Id: Id0a9a685536d5e18a3e42124a25ab08ff3a918f2
This change introduces a `flex_cellcount` field to `mjModel` to specify the number of cells in each dimension for interpolated flexes. The stiffness computation, passive force calculation, and Jacobian derivatives are updated to operate on a per-cell basis, significantly improving performance by localizing computations to the nodes within each cell.
PiperOrigin-RevId: 901216393
Change-Id: Ic23132e609de11e71bb7fef8d1f139daad2ec264
The frustum_top and frustum_bottom assignments in mjv_updateCamera used
the wrong elements of the zver array, causing the principal point cy
offset to be applied with an inverted sign. This shifted the rendered
image vertically by 2*cy pixels.
An earlier refactor incorrectly assumed that only selected bodies needed
labels.
PiperOrigin-RevId: 818568645
Change-Id: I7aea07c5342673dd589e1891d0db1f2b0c489fe4
- Make island visualization off by default
- Give it the keyboard shortcut 'N'
- Use HSV island coloring
PiperOrigin-RevId: 796375514
Change-Id: I3cc8d6f8142412c771b2b8e57e82e70000727770
Also, when a mesh has both an octree and a bvh, render only the octree.
PiperOrigin-RevId: 790680831
Change-Id: Iaf3896933f6728af4db1eaa83ff5b06558ab0d19
This prevents the taxels from being occluded by the convex hull for meshes that do not provide face connectivity.
PiperOrigin-RevId: 790420616
Change-Id: I543fd7b52e4625d921b6b5b5b77b4720020df42a
Yuval Tassa