Add texture attribute to lights.

PiperOrigin-RevId: 763739805
Change-Id: I333ed2ac68f30f79f688ca01d7b5fd6bf2d836c9

src/user/user_objects.h

@@ -793,6 +793,9 @@ class mjCLight_ : public mjCBase {
  protected:
   mjCBody* body;                  // light's body
   int targetbodyid;               // id of target body; -1: none
+  int texid;                      // id of texture; -1: none
+  std::string texture_;
+  std::string spec_texture_;
   std::string targetbody_;
   std::string spec_targetbody_;
 };
@@ -814,6 +817,7 @@ class mjCLight : public mjCLight_, private mjsLight {
 
   // used by mjXWriter and mjCModel
   const std::string& get_targetbody() const { return targetbody_; }
+  const std::string& get_texture() const { return texture_; }
 
   void SetParent(mjCBody* _body) { body = _body; }
   mjCBody* GetParent() const { return body; }