Per-point colors in point clouds

[chapulina]

🎉 New feature

• Part of Generic point cloud visualization gz-sim#1156
• Needed by Set per-point color on markers gz-gui#318

Summary

We have been populating the colors vector in Ogre2DynamicRenderable, but not using the colors for anything.

For most dynamic renderables, we fill the vertex buffer with position and normal. But points don't have normals, so we've been leaving half the buffer empty. The implementation on this PR takes advantage of those empty slots to place per-point colors (only RGB, no A).

Thanks @WilliamLewww for helping me out with this!

Test it

The marker example on gazebosim/gz-gui#318 uses this:

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)
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[codecov]

Codecov Report

Merging #494 (2eb00dd) into main (8143932) will increase coverage by 1.93%.
The diff coverage is 63.79%.

@@            Coverage Diff             @@
##             main     #494      +/-   ##
==========================================
+ Coverage   52.22%   54.16%   +1.93%     
==========================================
  Files         203      203              
  Lines       20215    20227      +12     
==========================================
+ Hits        10557    10955     +398     
+ Misses       9658     9272     -386     

Impacted Files	Coverage Δ
ogre2/src/Ogre2Camera.cc	84.84% <ø> (+13.33%)	⬆️
ogre2/src/Ogre2Marker.cc	41.93% <ø> (+1.05%)	⬆️
ogre2/src/Ogre2RayQuery.cc	72.54% <0.00%> (+31.54%)	⬆️
src/Utils.cc	98.70% <ø> (+22.91%)	⬆️
ogre2/src/Ogre2LidarVisual.cc	81.55% <20.00%> (+0.87%)	⬆️
ogre2/src/Ogre2DynamicRenderable.cc	73.42% <50.00%> (-1.58%)	⬇️
ogre2/src/Ogre2SelectionBuffer.cc	93.17% <83.87%> (+93.17%)	⬆️
ogre2/src/Ogre2RenderTarget.cc	85.38% <0.00%> (+0.92%)	⬆️
src/base/BaseScene.cc	72.54% <0.00%> (+1.84%)	⬆️
ogre2/src/Ogre2Scene.cc	76.80% <0.00%> (+2.46%)	⬆️
... and 7 more

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[iche033]

works for me. I made some changes in the iche033/6/marker_point_color branch for Metal. I don't have a working mac setup to test it though.

Using the normal buffer is fine. I know that in ogre 1.x, you can create vertex element of type VES_DIFFUSE to store colors per vertex (e.g. in place of VES_NORMAL if operationType is point list) but I couldn't find examples that does it in ogre 2.x so not sure how well it's working. Otherwise, that would probably be a more semantically correct way to pass colors to shaders.

[chapulina]

I made some changes in the iche033/6/marker_point_color branch for Metal.

Thanks! Merged in.

[chapulina]

FYI, I rebased this PR to Garden (main), because downstream PRs have breaking changes that need to target Garden. If there's a need to backport this to Fortress later I can open a separate PR.

[iche033]

looks good to me.