Error casting user data: Unexpected index

[darksylinc]

Chasing this bug where INTEGRATION_lidar_visual prints:

[Err] [Ogre2GpuRays.cc:262] Error casting user data: Unexpected index

in stderr which aren't happening in Edifice which ended up not being a rendering bug, I noticed that if I force retroValue = -1 the items from INTEGRATION_lidar_visual still do get rendered using standard PBS shaders in both Edifice (2.1) and Fortress (2.2).

These reveals two possible bugs:

1. laser_retro is not set anywhere. except ign-gazebo/src/rendering/SceneManager.cc and ign-rendering/test/integration/gpu_rays.cc but neither of them are set during INTEGRATION_lidar_visual test. Due to this change, it appears that previously by default Variant would return int 0, whereas now a default Variant will throw when trying to cast to any type because none is set.

2. If I force retroValue = -1 the items from INTEGRATION_lidar_visual still do get rendered using standard PBS shaders even though the code later messes with visibility flags:

if (retroValue >= 0)
{
  // set visibility flag so the camera can see it
  item->addVisibilityFlags(0x01000000);
  // ...
}

which suggests that the intended path is that items whose retroValue is not set should not be rendered; however they are being rendered.

Environment

• OS Version: Ubuntu 18.04 LTS
• Source or binary build?
  Source. main branch

Description

• Expected behavior: No errors printed on stderr. Likely appropriate objects should switch to use the custom low level material while the rest is not rendered (instead of being rendered using standard PBS).
• Actual behavior in main: Errors are printed on stderr and objects are being rendered using PBS shaders
• Behavior in Edifice: No stderr. All objects are switched to low level material because laser_retro defaults to 0 when unset. However if an object explicitly sets laser_retro to a negative value, objects will still be rendered using PBS, which is likely a bug.

Steps to reproduce

1. Run INTEGRATION_lidar_visual in main

Output

Lots of:

[Err] [Ogre2GpuRays.cc:262] Error casting user data: Unexpected index

Test still passes anyway but looks like random chance. Inspecting the RenderTarget shows results are quite different

Reference result (uses custom low level material shader):

Reference wireframe:

Failure result (uses PBS shaders. I don't think this element should be getting rendered at all!):

Failure wireframe:

[darksylinc]

I noticed the error got fixed and closed but the behavior is still different.

• Before Prevent default-constructed variants from holding a type #371, not setting laser_retro would result in the material getting swapped because it defaulted to 0
• With the current fix, the object will be rendered using PBR shaders which is likely unwanted

If this new behavior is desired then ignore my comment

Update: ahhh nevermind, I missed that visibility flags were updated too