A tiny ray caster game rendered using raw SDL2, written in F#:
This is an F# version of the excellent tutorial here by Dmitry V. Sokolov.
Why? Because I wanted to have a go using raw SDL2 from F# (not even using the SDL2-CS bindings from flibitijibibo).
Also, given that Dmitry's work is just 486 lines of C++, I was interested to see how a language almost on the other end of the high/low spectrum from C++ would do :)
This has been coded in .NET Core 2.2, using VS Community 2017 on Windows 10. You can run it either using VS, or via dotnet run on the command line.
I have not tested it on other platforms - the only likely point of incompatibility would be the SDL2 library: included is the SDL2.dll from 2.0.9 for 64 bit windows.
Alternative versions of SDL can be acquired from here
Things I learned building this include:
- the netbpm format (https://en.wikipedia.org/wiki/Netpbm_format)
- to open/view ppm files, I had to install gimp on windows.
- on linux/osx, it might be easier to install & use display in the terminal
- ppm is an uncompressed image format, so is not generally recommended for images (which is probably why the support is so poor, plus its almost 40 years old)
- Note: when I move to SDL, I removed the ppm code. Its in the history around this commit if you want to see it.
- basic raycasting for wolfenstein 3D-esque rendering
- the 'fish-eye' issue when rendering is something I learned more about (specifically how to solve it) from The Black Book by Fabien Sanglard. I recommend it.
- I didn't include the monsters from Dmitry's demo - I was more interested in ray casting and SDL interop, to be honest. Maybe something to do in future.
- As a performance improvement, the raycasting uses a more granular jump rate, then walks back to find the exact point once it finds a hit.
- SDL2 Interop and Interop and general
- My implementation is a combination of replicating what Dmitry did, with a conversion of the interop declarations by Flibit
- I restricted to just what I need, so the SDL interop module is quite small. Where appropriate, I would declare flag-like constants as their raw value, generally derived by running SDL2-CS as a console app to get the value and then putting it here (e.g. SDL_PIXELFORMAT_ABGR8888 as 376840196u)
- Event polling was complicated, and I ended up restricting to just the event I needed. The union hack in the SDL2-CS lib I couldn't get working with F# (ironic, since F# actually has unions)
- Other reasons for not using SDL2-CS (i.e. other than the educational challenge) is that I only need a small subset of SDL2's signature, and SDL2-CS is not net standard (its Net Framework 4, as opposed to this project which is Net Core 2.2).