Add light ids.

PiperOrigin-RevId: 805755907
Change-Id: I92a1b1ea4ce1495c2746fd518f33ab2d1ad81399

doc/includes/references.h

@@ -2861,6 +2861,7 @@ struct mjvGeom_ {                 // abstract geom
 };
 typedef struct mjvGeom_ mjvGeom;
 struct mjvLight_ {                // OpenGL light
+  int      id;                    // light id, -1 for headlight
   float    pos[3];                // position rel. to body frame
   float    dir[3];                // direction rel. to body frame
   int      type;                  // type (mjtLightType)

include/mujoco/mjvisualize.h

@@ -259,6 +259,7 @@ typedef struct mjvGeom_ mjvGeom;
 //---------------------------------- mjvLight ------------------------------------------------------
 
 struct mjvLight_ {                // OpenGL light
+  int      id;                    // light id, -1 for headlight
   float    pos[3];                // position rel. to body frame
   float    dir[3];                // direction rel. to body frame
   int      type;                  // type (mjtLightType)

python/mujoco/introspect/structs.py

@@ -6697,6 +6697,11 @@ STRUCTS: Mapping[str, StructDecl] = dict([
          name='mjvLight',
          declname='struct mjvLight_',
          fields=(
+             StructFieldDecl(
+                 name='id',
+                 type=ValueType(name='int'),
+                 doc='light id, -1 for headlight',
+             ),
              StructFieldDecl(
                  name='pos',
                  type=ArrayType(

python/mujoco/structs.cc

@@ -1076,6 +1076,7 @@ This is useful for example when the MJB is not available as a file on disk.)"));
       [](MjvLightWrapper& c, decltype(raw::MjvLight::var) rhs) {   \
         c.get()->var = rhs;                                        \
       })
+  X(id);
   X(cutoff);
   X(exponent);
   X(headlight);

src/engine/engine_vis_visualize.c

@@ -2310,6 +2310,7 @@ void mjv_makeLights(const mjModel* m, const mjData* d, mjvScene* scn) {
 
     // set default properties
     memset(thislight, 0, sizeof(mjvLight));
+    thislight->id = -1;
     thislight->headlight = 1;
     thislight->texid = -1;
     thislight->type = mjLIGHT_DIRECTIONAL;
@@ -2341,6 +2342,7 @@ void mjv_makeLights(const mjModel* m, const mjData* d, mjvScene* scn) {
 
       // copy properties
       memset(thislight, 0, sizeof(mjvLight));
+      thislight->id = i;
       thislight->type = m->light_type[i];
       thislight->texid = m->light_texid[i];
       thislight->castshadow = m->light_castshadow[i];

unity/Runtime/Bindings/MjBindings.cs

@@ -6110,6 +6110,7 @@ public unsafe struct mjvGeom_ {
 
 [StructLayout(LayoutKind.Sequential)]
 public unsafe struct mjvLight_ {
+  public int id;
   public fixed float pos[3];
   public fixed float dir[3];
   public int type;