README.md
doom-nano

A 3d raycast engine for Arduino



See it in action:
- ]]>https://youtu.be/wJG04DSo7Xw]]> (Progress on Feb, 09 2019)
- ]]>https://youtu.be/FX7PQtUAkHk]]> (Progress on Jan, 18 2019)

Just experimenting with an Arduino Nano I bought some time ago. This chip is very limited in process and memory: 16Mhz, only 32kb for program memory and 2kb of RAM, of which 1kb is entirely used for the screen.
Most of problems I´m facing currently are about memory. CPU clock might be a problem too, but can be more or less avoided having more memory for calculation shortcuts.
Despite of all those limitations, I managed to make it run at 8-11 FPS with most of stuff already done. Probably can be optimized and structured much better. Will try to keep learning and improve it.

To be clear. This is not an actual Doom game, just picked some sprites from it (and simplified a lot). The rendering engine is more like a Wolfeistein 3D. The Doom idea came because I started this building the fancy melt-screen effect (included in early version, but not anymore).

Hardware I used:
- Protoboard
- Arduino nano V3 (ATmega328P)
- OLED Display (i2c 128x64)
- 4 buttons
- 4 10k ohms resistors (Optional. You can use internal pull-up resistor by uncommenting the #define USE_INPUT_PULLUPS from constants.h file)

Resources:
- Sprites from ]]>https://www.spriters-resource.com]]>
- Much thanks to ]]>https://lodev.org/cgtutor]]> for so wonderful resource about raycasting engines

Current status:
- The map rendering is working nicely. Even I was able to add a depth effect by using different dithering patterns, depending on the distance to the view.
- Sprites are working too, though has some issues hiding them behind walls because memory limitations (the z-buffer precision has been limited a lot to make it smaller).
- You can move through the map, collide with walls, collect items and interact with enemies. I could also add the jogging effect, like Doom´s one.
- The enemies AI, despite is very simple, I think works very well and it´s enough for the purpose of the game. Looks very similar to  Imp enemy from original Doom.
- For the HUD, I realized that the native print from Adafruit's library uses too much memory. So I've implemented my custom text rendering methods and a custom font which includes only needed characters and some icons. 
- Currently I´m using 99% of program memory, which doesn´t let me adds more code. I need to research how to optimize it to make it smaller.

(I'd like) To do:
- ~~Make possible kill enemies.~~
- Doors and locked doors.
- A game over screen.
- Add more sprites, decorative elements, etc.
- Textures? Very performance expensive. I don't think so.
- Make code looks nicer! Move all to pure c++.
- Sound/Music? Hmmm I wish so, but...

More screens (outdated):