Mouse functionality for segmentation camera demo is incomplete

[adlarkin]

Environment

• OS Version: Ubuntu 18.04
• Source or binary build?
  Source: Segmentation Camera #329
• If this is a GUI or sensor rendering bug, describe your GPU and rendering system. Otherwise delete this section.
  • Rendering plugin: ogre2

Description

There are several mouse features that don't work with the segmentation camera demo:

1. Ray query code causes a crash: https://github.com/ignitionrobotics/ign-rendering/blob/e185ecd74c3dd979a06740d54fd010bf146eb15b/examples/segmentation_camera/GlutWindow.cc#L160
2. Mouse wheel scrool zoom doesn't work: https://github.com/ignitionrobotics/ign-rendering/blob/e185ecd74c3dd979a06740d54fd010bf146eb15b/examples/segmentation_camera/GlutWindow.cc#L170-L171
3. Right mouse button zoom doesn't work: https://github.com/ignitionrobotics/ign-rendering/blob/e185ecd74c3dd979a06740d54fd010bf146eb15b/examples/segmentation_camera/GlutWindow.cc#L206-L207

Steps to reproduce

1. build the segmentation camera demo example:

cd ign-rendering/examples/segmentation_camera
mkdir build
cd build
cmake .. && make

2. Run the example and try to use the scroll wheel or right click button on your mouse (they won't work):

./segmentation_camera

3. Try to uncomment the ray query code (point 1 in the Description section above) and the rebuild/re-test the example. A crash occurs when you click on the GUI display

[darksylinc]

If you post a callstack of the crash to the rayquery:

    // TODO(anyone) figure out why this code is causing a crash
    // g_rayQuery->SetFromCamera(rayCamera, ignition::math::Vector2d(nx, ny));
    // g_target  = g_rayQuery->ClosestPoint();
    // if (!g_target)
    // {
    //   // set point to be 10m away if no intersection found
    //   g_target.point = g_rayQuery->Origin() + g_rayQuery->Direction() * 10;
    //   return;
    // }

I might be able to spot what's going on, or at least give you a hint.

[adlarkin]

If you post a callstack of the crash to the rayquery

If I uncomment the code you highlighted in your comment and then run the example again, I get a crash with the only output being this:

Segmentation fault (core dumped)

It looks like it's coming from this line: https://github.com/ignitionrobotics/ign-rendering/blob/d2ff058e0b93d61cec514ead5293f6f53c2c8597/examples/segmentation_camera/GlutWindow.cc#L161

Doing some more digging, I find that the segfault actually occurs here: https://github.com/ignitionrobotics/ign-rendering/blob/d2ff058e0b93d61cec514ead5293f6f53c2c8597/ogre2/src/Ogre2RayQuery.cc#L67

It looks like the input camera pointer (_camera) is not null, but when it's converted to an Ogre2Camera, it is null. So, this must mean that the input _camera is not of type Ogre2Camera? Looking at the example code, the segmentation camera is created here. Is there something wrong with the inheritance structure of the segmentation camera?

[iche033]

Ogre2SegmentationCamera :
      public BaseSegmentationCamera<Ogre2Sensor>

oh looks like it inherits from Ogre2Sensor and not Ogre2Camera so the cast fails.

[adlarkin]

Would it be possible to change the inheritance template type to Ogre2Camera without breaking ABI since ogre2 is a separate component/plugin?

Also, I believe that mouse functionality with the ray query for the example in #334 works just fine (at least, it did last time I tried it) and it looks like the inheritance structure is similar to the segmentation camera 🤔

[iche033]

Would it be possible to change the inheritance template type to Ogre2Camera without breaking ABI since ogre2 is a separate component/plugin?

we are installing the ogre2 comopnent headers so that'll break ABI.

looks like the bounding box demo creates 2 cameras: 1 regular camera, and 2 bounding box camera. Ray queries are created by the regular camera. We could probably do the same workaround for the segmentation camera demo

[azeey]

Fixed by #483