Optionally disable "render back faces" for the shadow caster

[WilliamLewww]

Added a new SDF parameter ignition:shadow_caster_render_back_faces to specify if back faces should be rendered by the shadow caster.

<scene>
  <ignition:shadow_caster_render_back_faces>0</ignition:shadow_caster_render_back_faces>
  <background>0.0 0.0 0.0 1</background>
</scene>

Currently, the scene is hard-coded to always render back faces.

Based off pull request: #3048

[iche033]

looks good, just some minor comments

[iche033]

this looks fine. I think if we plane to add more shadow params in the future, we can consider adding a <shadows> </shadows> section to group these parameters

[scpeters]

we could consider adding this new field to scene.proto in the ign-msgs main branch, similar to gazebosim/gz-msgs#179

[iche033]

just made one very minor comment. Otherwise looks good.

[scpeters]

we included a test in #3048. would it be hard to do so here as well?

[WilliamLewww]

we included a test in #3048. would it be hard to do so here as well?

I added a test for the shadow caster render back faces.

[scpeters]

we included a test in #3048. would it be hard to do so here as well?

I added a test for the shadow caster render back faces.

thanks! the test looks great. I just fixed one more xml glitch in ef25689 and will merge once CI has finished again

[scpeters]

we included a test in #3048. would it be hard to do so here as well?

I added a test for the shadow caster render back faces.

thanks! the test looks great. I just fixed one more xml glitch in ef25689 and will merge once CI has finished again

unfortunately the new test is failing on macOS

• https://build.osrfoundation.org/job/gazebo-ci-pr_any-homebrew-amd64/2574/testReport/junit/(root)/ShadowCasterRenderBackFacesTest/ShadowCasterBackFaces/

I'll try to reproduce and debug the failure on my laptop

[WilliamLewww]

we included a test in #3048. would it be hard to do so here as well?

I added a test for the shadow caster render back faces.

thanks! the test looks great. I just fixed one more xml glitch in ef25689 and will merge once CI has finished again

unfortunately the new test is failing on macOS

* https://build.osrfoundation.org/job/gazebo-ci-pr_any-homebrew-amd64/2574/testReport/junit/(root)/ShadowCasterRenderBackFacesTest/ShadowCasterBackFaces/

I'll try to reproduce and debug the failure on my laptop

Could this be the same thing that made the test fail for #3048? I remember resorting to excluding the test on MacOS.

[scpeters]

the test passes on my laptop; let's just merge it as is