Allow to convert URDF color to SDF material tag

[ahcorde]

Signed-off-by: ahcorde ahcorde@gmail.com

🦟 Bug fix

This PR tries to fix this issue #513 where the URDF gazebo material tags are incorrectly translated

As a general overview:

• URDF defined the color as rgba but in ignition the color is defined as ambient, specular and diffuse. URDF definition
• The other way to use a color in the URDF format is with OGRE materials, but according with the migration guide there is no support for this.

This solution will not break the old behaviour, if there is any <material> tag under a <gazebo> tag, then the tag will be replaced.

Summary

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Code check passed (In source directory, run sh tools/code_check.sh)
• All tests passed (See
  test coverage)
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[nkoenig]

Is it possible to add a test?

[peci1]

Will this be compatible with Gazebo Classic in case only the URDF color is defined?

[ahcorde]

Will this be compatible with Gazebo Classic in case only the URDF color is defined?

Gazebo11 (classic) is using sdformat9, this PR is targeting sdformat11. This should not affect Gazebo classic: Gazebo9 or Gazebo11.

What do you think @nkoenig ? should I retarget this to sdformat9? and make it compatible with Citadel ?

[nkoenig]

Will this be compatible with Gazebo Classic in case only the URDF color is defined?

Gazebo11 (classic) is using sdformat9, this PR is targeting sdformat11. This should not affect Gazebo classic: Gazebo9 or Gazebo11.

What do you think @nkoenig ? should I retarget this to sdformat9? and make it compatible with Citadel ?

I don't see a problem leaving this PR targeted toward sdformat11. No reason to potentially upset Gazebo classic.

[ahcorde]

@nkoenig Test added

[ahcorde]

I'm going to close this PR because there is a way to include the color without adding new code, for example:

<link name='cart'>
...
</link>
<gazebo reference="cart">
    <visual>
      <material>
        <ambient>0 0 1 1</ambient>
        <diffuse>0 0 1 1</diffuse>
        <specular>0 0 1 1</specular>
      </material>
    </visual>
</gazebo>

[peci1]

there is a way to include the color without adding new code

That's only part-wise solution. This way, you can only set a single material to all <visual> tags of the link. Using the URDF color tags, you set the color per-<visual>. This can be overcome by splitting the visual elements to multiple lumped links, but it's impractical at least...

[ahcorde]

friendly ping @nkoenig

[ahcorde]

friendly ping @azeey

[azeey]

I tried to using an example to compare the colors between Rviz and ign-gazebo (with examples/world/empty.sdf). It still doesn't match quite right. ign-gazebo is much brighter.
. I don't know if this an issue with ign-gazebo or not. I'll go ahead and approve since the values used for the conversion seem reasonable to me.

[ahcorde]

Merging I ticketed an issue

[peci1]

Are there plans for backporting to sdf10?