Add mj_multiRay function to perform multiple ray intersection with the same source.

PiperOrigin-RevId: 528684535
Change-Id: I6e1747a4a0910e6061d6154e19ad8723f56c22e3

src/engine/engine_ray.h

@@ -23,6 +23,16 @@
 extern "C" {
 #endif
 
+MJAPI void mju_multiRayPrepare(const mjModel* m, const mjData* d, const mjtNum pnt[3],
+                               const mjtNum* ray_xmat, const mjtByte* geomgroup, mjtByte flg_static,
+                               int bodyexclude, mjtNum* geom_ba, int* geom_eliminate);
+
+// Intersect multiple rays emanating from a single source
+// Similar semantics to mj_ray, but vec is an array of (nray x 3) directions.
+MJAPI void mj_multiRay(const mjModel* m, mjData* d, const mjtNum pnt[3], const mjtNum* vec,
+                       const mjtByte* geomgroup, mjtByte flg_static, int bodyexclude,
+                       int* geomid, mjtNum* dist, int nray);
+
 // intersect ray (pnt+x*vec, x>=0) with visible geoms, except geoms on bodyexclude
 //  return geomid and distance (x) to nearest surface, or -1 if no intersection
 //  geomgroup, flg_static are as in mjvOption; geomgroup==NULL skips group exclusion