Make mjs_findElement find textures by file name.

This is done if the model is uncompiled and their name is empty.

PiperOrigin-RevId: 772885774
Change-Id: I827d5b679637fa0571cfb0a69833ed688df16304

python/mujoco/specs_test.py

@@ -1001,6 +1001,14 @@ class SpecsTest(absltest.TestCase):
     texture.data = np.zeros((2, 2, 3), dtype=np.uint8).tobytes()
     spec.compile()
 
+  def test_find_unnamed_texture(self):
+    spec = mujoco.MjSpec()
+    texture_file = spec.add_texture(file='file.png')
+    texture_name = spec.add_texture(name='name')
+    self.assertEqual(spec.texture('file'), texture_file)
+    self.assertEqual(spec.texture('name'), texture_name)
+    self.assertIsNone(spec.texture('none'))
+
   def test_attach_units(self):
     child = mujoco.MjSpec()
     parent = mujoco.MjSpec()

src/user/user_api.cc

@@ -936,6 +936,8 @@ mjsElement* mjs_findElement(mjSpec* s, mjtObj type, const char* name) {
     case mjOBJ_LIGHT:
     case mjOBJ_FRAME:
       return model->FindTree(model->GetWorld(), type, std::string(name));  // recursive search
+    case mjOBJ_TEXTURE:
+      return model->FindTexture(std::string(name));  // check filename too
     default:
       return model->FindObject(type, std::string(name));  // always available
   }

src/user/user_model.cc

@@ -24,6 +24,7 @@
 #include <cstdlib>
 #include <cstring>
 #include <exception>
+#include <filesystem>  // NOLINT(build/c++17)
 #include <functional>
 #include <mutex>
 #include <string>
@@ -1369,6 +1370,23 @@ static T* findobject(std::string_view name, const vector<T*>& list, const mjKeyM
   return list[id->second];
 }
 
+
+
+mjCBase* mjCModel::FindTexture(std::string_view name) const {
+  for (unsigned int i=0; i < textures_.size(); i++) {
+    if (textures_[i]->name == name) {
+      return textures_[i];
+    }
+    if (textures_[i]->name.empty() &&
+        std::filesystem::path(textures_[i]->spec_file_).filename().stem() == name) {
+      return textures_[i];
+    }
+  }
+  return nullptr;
+}
+
+
+
 // find object in global lists given string type and name
 mjCBase* mjCModel::FindObject(mjtObj type, string name) const {
   if (!object_lists_[type]) {

src/user/user_model.h

@@ -248,6 +248,7 @@ class mjCModel : public mjCModel_, private mjSpec {
   mjCDef* FindDefault(std::string name);                            // find defaults class name
   mjCDef* AddDefault(std::string name, mjCDef* parent = nullptr);   // add defaults class to array
   mjCBase* FindObject(mjtObj type, std::string name) const;         // find object given type and name
+  mjCBase* FindTexture(std::string_view name) const;                // find texture given name
   mjCBase* FindTree(mjCBody* body, mjtObj type, std::string name);  // find tree object given name
   mjSpec* FindSpec(std::string name) const;                         // find spec given name
   mjSpec* FindSpec(const mjsCompiler* compiler_);                   // find spec given mjsCompiler