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https://github.com/izabera/pseudo3d

a raycaster in bash
https://github.com/izabera/pseudo3d

3d bash gamedev raycasting terminal terminal-based terminal-game tui

Last synced: 5 months ago
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a raycaster in bash

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# a raycaster in bash



https://github.com/user-attachments/assets/59851903-cf4c-4dfc-afae-3c533f6241f7



more screenshots/vidoes at https://imgur.com/a/izas-wolfenstein-bash-journey-bAy5zhp



largely a port of https://lodev.org/cgtutor/raycasting.html



use the arrow keys to rotate and move around, and q to quit



### why this was a bit hard



- bash is slow.  this is by far the biggest issue.  it's so slow that you

  cannot possibly achieve an acceptable frame rate if you have to execute even

  a single command per pixel.  this implies that you also cannot keep the state

  of the screen in memory, neither as an array of colours (did you know that

  accessing a random element in an array takes linear time?) nor as a single

  long string (did you know that accessing the nth character in a string takes

  linear time even in LANG=C?), because literally just reading this

  representation to dump it to the screen will take longer than a frame



- bash has no floating point support nor access to a library of maths

  functions. all the maths is done on integers, scaled up by 64k



- terminals are ugly if you use a full character to represent each pixel, so

  this uses unicode half blocks with different foreground and background

  colours, which effectively doubles the vertical resolution.  there is

  unfortunately no way to update only one of the two colours in a cell, nor any

  way to query the current colours of a cell (besides, it would be too slow for

  bash), so every time we write a pixel we need to know the colour of an

  adjacent pixel.  it would be really convenient if bash could store the state

  somehow but alas it cannot



- various misc annoyances:

    - making sure all the terminal is updated at once is not trivial with a

      slow language like bash



    - most terminals are not designed to play video games in (shockingly), so

      you cannot test if a key is currently pressed.  instead you can only get

      a single key that's being held down, usually really slowly debounced and

      with a low limit for continued presses, so you probably get like 5-6

      characters a second.  you cannot even get multiple keys pressed at the

      same time unless some are modifiers.  the kitty keyboard protocol 100%

      fixes all this, and i'm sure it will become a widely implemented standard

      by the year 2100



    - turns out that filling a terminal with colours takes a lot of data.  at

      my normal font size this does ~10mb of i/o per second, which isn't very

      much in the grand scheme of things, but, you know, it's bash



    - bash will never use a single syscall to print a string with more than one

      newline, regardless of the type of file you're writing to.  this is

      pointless and dumb, and it's the reason why this never prints \n and

      always moves the cursor in other ways.  ultimately this ended up printing

      more data than the size your terminal is likely getting in each read, so

      it might not matter too much, but it still bothered me



    - ecma48/vt100/vt200/xterm... were all designed by insane people who hated

      me specifically



    - holy shit i'm bad at maths, i went to uni for this what the fuck



### faq



- q: it fucks things up when i resize the window/it's a flickery mess/it

     generally looks like shite on my terminal

- a: open an issue please



- q: my cpu heats up like crazy/my computer from 2005 slows down to a crawl

- a: try to reduce the resolution, or set the env variable FPS to something less

     than 30.  also, microsoft defender is known to do everything it can to tank

     any resemblance of performance, so maybe disable it



- q: it doesn't work on my bash < 5.2

- a: yep



- q: is this code all pure bash?

- a: no.  it also calls stty once at startup to disable echo, and once at exit

     to re enable it.  and some stats at the end are collected via other tools



### roadmap



- [x] semi-accurate pseudo 3d

- [x] fluid movement

- [x] decent framerate

- [x] parallel rendering

- [x] 24 bit colours

- [x] kitty keyboard protocol

- [ ] mouse support

- [x] framerate-independent speed

- [ ] textures

- [ ] sprites

- [ ] objects/enemies

- [ ] particles

- [x] sound (VERY EARLY PROTOTYPE)

- [ ] better perf

- [ ] multiplayer

- [x] dynamic wall colours

- [x] dynamic map (it technically is but no events change it at the moment)

- [x] basic animations effects for walls

- [x] basic on-screen minimap