Add multiccd fields to MJX and add simplex box-mesh model.

PiperOrigin-RevId: 813190617
Change-Id: Idc450da59d6420825077a642719525750f6551ec

mjx/mujoco/mjx/_src/types.py

@@ -615,6 +615,15 @@ class ModelC(PyTreeNode):
   D_colind: jax.Array  # pylint:disable=invalid-name
   mapM2D: jax.Array  # pylint:disable=invalid-name
   mapD2M: jax.Array  # pylint:disable=invalid-name
+  mesh_polynum: jax.Array
+  mesh_polyadr: jax.Array
+  mesh_polynormal: jax.Array
+  mesh_polyvertadr: jax.Array
+  mesh_polyvertnum: jax.Array
+  mesh_polyvert: jax.Array
+  mesh_polymapadr: jax.Array
+  mesh_polymapnum: jax.Array
+  mesh_polymap: jax.Array
 
 
 class ModelJAX(PyTreeNode):
@@ -649,6 +658,9 @@ class Model(PyTreeNode):
   nmeshtexcoord: int
   nmeshface: int
   nmeshgraph: int
+  nmeshpoly: int
+  nmeshpolyvert: int
+  nmeshpolymap: int
   nhfield: int
   nhfielddata: int
   ntex: int

test/engine/testdata/collision_convex/box_boxmesh.xml

@@ -0,0 +1,25 @@
+<mujoco model="Box mesh with multiccd">
+  <option>
+    <flag multiccd="enable"/>
+  </option>
+
+  <asset>
+    <mesh name="box"
+          vertex="-1 -1 -1
+                   1 -1 -1
+                   1  1 -1
+                   1  1  1
+                   1 -1  1
+                  -1  1 -1
+                  -1  1  1
+                  -1 -1  1"/>
+  </asset>
+
+  <worldbody>
+    <geom pos="0 0 -1" type="box" size="5 5 1"/>
+    <body pos="0 0 0.9999">
+      <freejoint/>
+      <geom type="mesh" mesh="box"/>
+    </body>
+  </worldbody>
+</mujoco>