In Leadwerks, required files were always a slightly awkward issue. The engine requires a BFN texture and a folder of shaders, in order to display anything. One of my goals is to make the Ultra Engine editor flexible enough to work with any game. It should be able to load the folder of an existing game, even if it doesn't use Ultra Engine, and display all the models and scenes with some accuracy. Of course the Quake game directory isn't going to include a bunch of Ultra Engine shaders, so what to do?

One solution could be to load shaders and other files from the editor directory, but this introduces other issues. My solution is to build shaders, shader families, and the default BRDF texture into the engine itself. This is done with a utility that reads a list of files to includes, then loads each one and turns it into an array in C++ code that gets compiled into the engine: The code looks like this:

       if (rpath == RealPath("Shaders/Sky.json"))
       {
            static const std::array<uint64_t, 62> data = {0x61687322090a0d7bULL,0x6c696d6146726564ULL,0xd7b090a0d3a2279ULL,0x746174732209090aULL,0x9090a0d3a226369ULL,0x66220909090a0d7bULL,0xa0d3a2274616f6cULL,0x9090a0d7b090909ULL,0x555141504f220909ULL,0x909090a0d3a2245ULL,0x90909090a0d7b09ULL,0x6c75616665642209ULL,0x909090a0d3a2274ULL,0x909090a0d7b0909ULL,0x6573616222090909ULL,0x90909090a0d3a22ULL,0x909090a0d7b0909ULL,0x7265762209090909ULL,0x5322203a22786574ULL,0x532f737265646168ULL,0x762e796b532f796bULL,0x227670732e747265ULL,0x9090909090a0d2cULL,0x6d67617266220909ULL,0x5322203a22746e65ULL,0x532f737265646168ULL,0x662e796b532f796bULL,0x227670732e676172ULL,0x909090909090a0dULL,0x9090909090a0d7dULL,0x7d090909090a0d7dULL,0xd2c7d0909090a0dULL,0x756f64220909090aULL,0x90a0d3a22656c62ULL,0x909090a0d7b0909ULL,0x45555141504f2209ULL,0x90909090a0d3a22ULL,0x9090909090a0d7bULL,0x746c756166656422ULL,0x90909090a0d3a22ULL,0x90909090a0d7b09ULL,0x2265736162220909ULL,0x9090909090a0d3aULL,0x90909090a0d7b09ULL,0x7472657622090909ULL,0x685322203a227865ULL,0x6b532f7372656461ULL,0x34365f796b532f79ULL,0x732e747265762e66ULL,0x9090a0d2c227670ULL,0x7266220909090909ULL,0x3a22746e656d6761ULL,0x7265646168532220ULL,0x6b532f796b532f73ULL,0x72662e6634365f79ULL,0xd227670732e6761ULL,0x7d0909090909090aULL,0x7d09090909090a0dULL,0xd7d090909090a0dULL,0x90a0d7d0909090aULL,0xa0d7d090a0d7d09ULL,0xcdcdcdcdcdcdcd7dULL  };
            auto buffer = CreateBuffer(489); 
            buffer->Poke(0,(const char*)data.data(),489);
            return CreateBufferStream(buffer);
       }

An unsigned 64-bit integer is used for the data type, as this results in the smallest generated code file size.

Files are searched for in the following order:

1. A file on the hard drive in the specified path.
2. A file from a loaded package with the specified relative path.
3. A file built into the engine.

Therefore, if your game includes a modified version of a shader, the shader module will still be loaded from the file in your game directory. However, if you don't include any shaders at all, the engine will just fall back on its own set of shaders compiled into the core engine.

This gives Ultra Engine quite a lot more flexibility in loading scenes and models, and allows creation of 3D applications that can work without any required files at all, while still allowing for user control over the game shaders.

The screenshot here shows the Ultra Engine editor loading a Leadwerks project folder and displaying 3D graphics using the Ultra Engine renderer, even though the Leadwerks project does not contain any of the shaders and other files Ultra Engine needs to run: