Well, a few thing about PHP :
- Performance are quiet good ! We talk here about an embedded language : a lot of native C function calls, a few if/else/for and that's all. No 3D calculation is done with PHP
- We do not provide PHP bindings, we provide a native PHP interpreter in the engine, and that makes a real difference ! PHP is used for RayPHP, a set of functions in Raydium that allows things like automatic downloading of data. We also use it for SOAP WebServices in ManiaDrive (all on-line score management), and so on. Before anything, it's the huge versatility of PHP that makes me add it into the engine.
- A last good thing with PHP is that it's now a very common language: that exactly what we're trying to do with Raydium: easy.
- The available functions with RayPHP can be found in reg_api.c file. It's only a very small set of Raydium, as needed by RayPHP.
You may want to have a look to how current Python bindings are created with SWIG, it can probably help you.