Unable to create custom texture reference using an image

[itsron143]

Hi,

I'm trying to create a sand-like texture using a sand.png as the reference image.

(These additions can be found here)

Following the implementations of textures/_checker.py and textures/_.gradient.py, I created textures/._sand.py:

from dataclasses import dataclass, field

from revolve2.simulation.scene.geometry.textures import Texture, TextureReference


@dataclass(kw_only=True, frozen=True)
class Sand(Texture):
    """A sand-like texture using a image as reference"""

    reference: TextureReference = field(
        default_factory=lambda: TextureReference(
            content_type="image/png",
            file="./sand.png"
        )
    )

    repeat: tuple[int, int] = field(default=(100, 100))

I'm using this with a sand.png file to create a custom terrain with a modular robot similar to examples/1b_custom_terrain:

def make_custom_sand_terrain() -> Terrain:
    """
    Create a custom terrain with a sand.png as the texture reference.

    :returns: The created terrain.
    """
    return Terrain(
        static_geometry=[
            GeometryPlane(
                pose=Pose(position=Vector3(), orientation=Quaternion()),
                mass=0.0,
                size=Vector3([20.0, 20.0, 0.0]),
                texture=Sand(map_type=MapType.MAP2D,
                             reference=TextureReference(
                                 content_type="image/png",
                                 file="./sand.png")),
            ),
        ]
    )

However, when I try to run this custom example I get the following error:

File "/Users/rounakvyas/.pyenv/versions/revolve/lib/python3.10/site-packages/dm_control/mjcf/element.py", line 534, in _check_valid_attribute
raise AttributeError( AttributeError: 'content_type' is not a valid attribute for texture )

The complete error stack trace can be found here.

From what I understand, content_type is an attribute of TextureReference and not Texture, so I'm unable to understand how to resolve this.

All my additions to the code can be found here.

Any help will be really appreciated!

Thanks!

[oliverweissl]

Please look at the mujoco xml documentation,
there you see what attributes you need.

https://mujoco.readthedocs.io/en/2.3.6/XMLreference.html#asset-texture

[itsron143]

@oliverweissl Removing the content_type helped with this issue, thanks!

However, it still does not render the texture. When I pass the absolute file path for the reference image, the generated xml for Mujoco updates the file name and states that it does not identify the resource.

I pass the full path of the image file:

texture=Sand(map_type=MapType.MAP2D,
        reference=TextureReference(
        file='/Users/rounakvyas/Desktop/Work/VU/msc_thesis/playground/revolve2/_playground/terrains/sand.png')),

and I get the following error:

  File "/Users/rounakvyas/Desktop/Work/VU/msc_thesis/playground/revolve2/simulators/mujoco_simulator/revolve2/simulators/mujoco_simulator/_simulat
e_scene.py", line 53, in simulate_scene
    model, mapping = scene_to_model(
  File "/Users/rounakvyas/Desktop/Work/VU/msc_thesis/playground/revolve2/simulators/mujoco_simulator/revolve2/simulators/mujoco_simulator/_scene_t
o_model.py", line 138, in scene_to_model
    model = mujoco.MjModel.from_xml_string(xml)
ValueError: Error: resource not found via provider or OS filesystem: 'sand-2bc2fcc6eadee78ac261056a9fa5524812025ec3.png'
Object name = heightmap_0_texture, id = 0, line = 13, column = -1

When I check the xml file generated, I see that the sand.png file was updated to sand-2bc2fcc6eadee78ac261056a9fa5524812025ec3.png

<mujoco model="scene">
  <compiler autolimits="true" angle="radian"/>
  <option timestep="0.001" gravity="0 0 -9.8100000000000005" integrator="RK4"/>
  <visual>
    <headlight active="0"/>
  </visual>
  <default>
    <default class="/"/>
    <default class="mbs0/"/>
    <default class="mbs1/"/>
  </default>
  <asset>
    <texture name="heightmap_0_texture" type="2d" file="sand-2bc2fcc6eadee78ac261056a9fa5524812025ec3.png" rgb1="0 0 0" rgb2="0 0 0" width="100" h
eight="100"/>

It looks like revolve finds the filepath but then the file name gets updated and then mujoco throws a resource not found value error.

[itsron143]

Update: This turned out to be a bug in Mujoco itself :)
google-deepmind/mujoco#1685