Add description in README what is a valid input file for the example files

[dov]

All of the example file fail with the error "3d model or image file on the command line" if run without an argument. But there is no mentioning in the README or anywhere else that I could find what is considered a valid 3d model. I tried with STL, ive, and jpg, non non work. A clarification would be nice.

[robertosfield]

What is a valid model will depend upon whether you've built vsgXchange and for vsgQt's examples to have used this. A full list of 3rd party formats support by vsgXchange, and hence the vsgQt and vsgExamples examples can be found in the vsgXchange/READEME.md:

https://github.com/vsg-dev/vsgXchange/blob/master/README.md

The vsgExamples README.md mentions some of the env vars you can set up to help find the example data/shaders found in vsgExamples/data:

https://github.com/vsg-dev/vsgExamples/blob/master/README.md

If you haven't built vsgXchange and linked vsgQt or vsgExamples then you'll be only able to load the formats supported by the core VulkanSceneGraph, my guess is that you haven't got vsgXchange built and linked to vsgQt as I'd expect .stl and .jpg to both work fine.

For OpenSceneGraph formats you'll need to build VulkanSceneGraph, then osg2vsg then vsgXchange then vsgQt. The you'll be able to load .osgb and ,ive etc. as well as all the file formats supported by the OSG.