First game on a VulkanSceneGraph

[maisvendoo]

Hi! We are very small development team from Russia. We develop railway simulator since 2018. Early, it was based on OpenSceneGraph. Now we released on VulkanSceneGraph. Robert, thanks for you attention to problem in developmennt, you advice was very userfull in our work. I hope, Robert, you not angry, that we use VSG logo in this project. It based on VSG, I think it is right

You can see it here: https://github.com/maisvendoo/RRS/releases

I think, it is the first game in the World, wich uses VulkanSceneGraph...

[robertosfield]

Congratulations on the release.

We will need add some screenshots and details of the project to the https://vsg-dev.github.io/vsg-dev.io/screenshots/ :-)

I'm sure I'm not the only one who is curious about this stuff so...

• How long did it take you to port over the VulkanSceneGraph?
• What were the challenges?
• And benefits you saw?
• Future plans?

[maisvendoo]

Answer, by Nikolay Avilkin, our graphics programmer:

Details:
It is an open source railway simulator that allows you to ride on Russian railways and tries to accurately represent the physical processes occurring with rolling stock.
It is divided on 3 parts:

1. simulator (server), that is responsible for physics and processing of incoming signals from clients. It doesn't have a GUI and doesn't display anything by itself;
2. viewer (client), that is responsible for rendering the route and rolling stock, audio output, keyboard and mouse processing;
3. route-map - GUI app that lets you perform the work of a dispatcher and control traffic lights.
   Simulator have modular structure that lets people add their own routes, rolling stock and write their own dynamic libraries on C++ for handling their physics. This applies not only to whole mobile unit (like locomotive or wagon) but also to separate components (like train driver's crane and so forth), what lets you make some experiments with your equipment.

Port time:
We have only 3 people working with graphics and some of them had no previous experience with Vulkan or with graphics programming at all, so it took about a year to dive in graphics programming world and another year to actually transfer all features from OSG viewer to VSG viewer.

Challenges:
Across the development, there were many moments when viewer already shown close to necessary results but with strange artifacts, or crashing in half of case, or crashing with a specific rolling stock. These cases were hard to debug and required deep understanding of VSG and Vulkan.

Benefit:
New viewer already shows higher and, what's more important, more stable FPS and it is despite the fact, that we probably don't use some optimization technics yet.

Future plans:
Our plans for next release is astronomically correct daylight imitating, with shadows. Now enabling shadows greatly reduces FPS and we don't understand why yet.
Here are some more features that we want to add in future versions:

• custom ReaderWriter for glTF (currently animations in our models are connected to animations described in according .xml files through mesh name, so we need to fully load model and keep it in memory, we can't use PagedLOD in this way)
• quadratic division of route map, so that PagedLOD could be handled faster
• upgrading lightning
• our own route editor
• control with mouse (now mouse controls only camera, while keyboard is responsible for pressing buttons, switching tumblers and so on. It would be nice if everything could be controlled with mouse also)

Some screenshots from game
screenshots1.zip
screenshots2.zip

[robertosfield]

Thanks for the screenshots. Once I've cleared more on my work backlog I will create a specific page on the VSG Github Pages website for it.

FYI, the new vsgXchange::gltf ReaderWriter reads the gltf into a local gltf specific data structure including meta data, and has a SceneGraphBuilder class for converting the gltf data structure into VSG scene graph, so you can pass in your own subclass from SceneGraphBuilder to override how it creates the scene graph. I haven't created the wiring up to enable this but the basic design is written with this in mind so it's just a matter of setting things up so you can pass in your own SceneGraphBuilder via vsg::Options meta data.

I would have thought you'd be able to leverage this to provide you custom behaviors even when using PagedLOD. In fact the design on the new gltf and Tiles3D loaders are meant to facilitate this - as the new Tiles3D load uses PagedLOD.

[maisvendoo]

Some screens with custom shadow add lighting settings, from our user
screens.zip