Both internal and external plugins do not get loaded when running simulate executable

[HuronSPerera]

Intro

Hi!

I am a researcher at WebAI, I use MuJoCo for my research on robotics simulation. I tried to run MujocoTactileSensorPlugin using sample_tactile_sensor.xml provided with its GitHub repo. I used version 3.2.4 since that plugin uses the deprecated mju_rotVecMatT. The plugin does not get loaded and I get an XML Erro
r. Then I ran gear.xml in model\plugin\sdf with the latest mujoco version and I get the same error. I tracked down the issue to line 257 of engine_global_table.h where it is calling the function GetByKeyUnsafe() and the problem seems to be that the count() comes out as zero.

My setup

The issue was detected in Linux Ubuntu 18.04 and the debugging was done using MS Visual Studio on Windows 11.

What's happening? What did you expect?

Setting rgba="1 0 0 1" renders as green, I expected it to render as red.

Here is a screen-shot showing a green sphere:

Steps for reproduction

1. Load the model below.
2. Run the code below.
3. See green sphere (should be red).

Minimal model for reproduction

If you encountered the issue in a complex model, please simplify it as much as possible (while still reproducing the issue).

minimal XML

<mujoco>
  <worldbody>
    <light pos="0 0 1"/>
    <geom type="sphere" size="1" rgba="1 0 0 1"/>
  </worldbody>
</mujoco>

Code required for reproduction

import mujoco
import mediapy as media
model = mujoco.MjModel.from_xml_string(xml)
data = mujoco.MjData(model)

with mujoco.Renderer(model) as renderer:
  mujoco.mj_forward(model, data)
  renderer.update_scene(data)

  media.show_image(renderer.render())

Confirmations

• I searched the latest documentation thoroughly before posting.
• I searched previous Issues and Discussions, I am certain this has not been raised before.

[HuronSPerera]

Please ignore all the default answers that I left unedited below "My setup" in the bug report.

[Phaneendra293]

I am new to contributing to GitHub, and I want to contribute to this project. I want to try to reproduce the error. Do you think this would be a good first issue for me?

[Phaneendra293]

Which OS should I try for reproduction? Should I use Ubuntu or Windows? Does the error persist across OS?

[yuvaltassa]

I used version 3.2.4 since that plugin uses the deprecated mju_rotVecMatT

Eh? That function was just renamed and the plugin should be completely functional in 3.4.0 (right, @quagla ?)

Could you please try and upgrade to 3.4.0, and see if you still hgve a problem?

[HuronSPerera]

Which OS should I try for reproduction? Should I use Ubuntu or Windows? Does the error persist across OS?

Yes. The error persists across Ububtu, Windows and MacOS.

[HuronSPerera]

I used version 3.2.4 since that plugin uses the deprecated mju_rotVecMatT

Eh? That function was just renamed and the plugin should be completely functional in 3.4.0 (right, @quagla ?)

Could you please try and upgrade to 3.4.0, and see if you still hgve a problem?

I ran the gear.xml to load an internal plugin using the latest mujoco version and the error persists.

[vishalharkal15]

.take

[HuronSPerera]

Hi. I tested this out of the latest release instead of building from source. Then the plugin in gear.xml gets loaded. When building from source. I create a sub-directory called "build" and run cmake from that directory by the command "cmake ..". This is probably why the plugin libraries are not getting loaded in my source build. My question then is should I run cmake in the main folder instead of creating a sub-directory and running cmake from it.

[nickjrz]

The issue seems to be that internal and external plugins (SDF, elasticity, etc) aren't loading when you drag XML files into ./simulate. Turns out their CMakeLists.txt files were missing install directives, so while they were building fine they never got copied over to build/bin/mujoco_plugin/ where simulate actually looks for them. And the plugin loader only reads actual files, not symlinks.
A quick workaround is manually copy the plugins from build/lib/ to build/bin/mujoco_plugin/ for now so things work, pretty sure you can also do this with external plugins. Long term fix is add install directives to all plugins CMakeLists.txt files so they automatically get copied to the right place when you build.