[wip] Added transparent mode

[atharva-18]

🎉 New feature

Summary

Adds transparent mode to visuals

Test it

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

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[codecov]

Codecov Report

Merging #336 (605d7ee) into main (8c34f9d) will decrease coverage by 0.22%.
The diff coverage is 16.85%.

@@            Coverage Diff             @@
##             main     #336      +/-   ##
==========================================
- Coverage   57.92%   57.70%   -0.23%     
==========================================
  Files         166      166              
  Lines       16433    16522      +89     
==========================================
+ Hits         9519     9534      +15     
- Misses       6914     6988      +74     

Impacted Files	Coverage Δ
include/ignition/rendering/Visual.hh	100.00% <ø> (ø)
include/ignition/rendering/base/BaseVisual.hh	68.82% <0.00%> (-2.96%)	⬇️
ogre/src/OgreVisual.cc	16.57% <0.00%> (-6.63%)	⬇️
ogre2/src/Ogre2Visual.cc	70.12% <46.87%> (-6.10%)	⬇️

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[ahcorde]

TODO

• Add transparent to visualization_demo when this PR is in https://github.com/ignitionrobotics/ign-rendering/pull/326/files

[iche033]

transparency settings can be set through the Material class. Is it not working for your needs?

[atharva-18]

transparency settings can be set through the Material class. Is it not working for your needs?

I wanted to set the transparency for a particular visual rather than a material being used by multiple visuals, similar to the View as transparent mode in Gazebo classic.

[iche033]

I see. To do that, we need to make sure the material that each visual has is unique. That's done when the material is set, i.e. visual->SetMaterial(mat, true), with the second arg telling the visual to clone the material first so it now has a copy instead of an instance of the material. Afterwards, you can do:

auto mat = visual->Material();
mat->SetTransparency(...);

Then it should only affect that particular visual.

It's the same idea that's implemented in gazebo classic, except the transparency logic is being handled in the Material class instead of the Visual class.

[atharva-18]

I see. To do that, we need to make sure the material that each visual has is unique. That's done when the material is set, i.e. visual->SetMaterial(mat, true), with the second arg telling the visual to clone the material first so it now has a copy instead of an instance of the material. Afterwards, you can do:

auto mat = visual->Material();
mat->SetTransparency(...);

Then it should only affect that particular visual.

It's the same idea that's implemented in gazebo classic, except the transparency logic is being handled in the Material class instead of the Visual class.

This would be a better approach. I think we can move the transparency logic to ign-gazebo (since the material is cloned for each visual) -

auto mat = visual->Material();

if (showTransp)
  mat->SetTransparency(0.5);
else
  mat->SetTransparency(0.0);

[ahcorde]

@atharva-18, is this ready to merge?

Transparency test is failing on MacOS

https://build.osrfoundation.org/job/ignition_rendering-ci-pr_any-homebrew-amd64/1569/testReport/junit/(root)/Visual_VisualTest/Transparency_ogre2/

[atharva-18]

@ahcorde I have moved the transparency logic to ign-gazebo. PR - gazebosim/gz-sim#878. The transparency can be set for each material (as @iche033 suggested) since the material is cloned for each visual. This is similar to the Align Tool plugin.

[chapulina]

I have moved the transparency logic to ign-gazebo

Thanks, @atharva-18 . Does this mean this PR can be closed?

[atharva-18]

I have moved the transparency logic to ign-gazebo

Thanks, @atharva-18 . Does this mean this PR can be closed?

Yes, we can close this PR.