This engine uses the second core of the RP2040 microcontroller as a rasterizer to render 3D graphics.
It contains a small city as well as an outskirts featuring shootable zombies.
If all you want are .uf2 binaries, check the releases for the newest version.
You will need the PicoSystem SDK and the Pico SDK.
Create and enter a build folder and use the following command to configure Cmake:
cmake -DPICO_SDK_PATH=/path/to/pico-sdk -DPICOSYSTEM_DIR=/path/to/picosystem path/to/Pico3D
and then use make to build a .uf2 file.
- Creating and exporting a game world in Blender
- Material, lights and textures in Blender
- Exporting individual meshes
Check out Daft's Emulator for RP2040.
Pico3D was created as part of a master's thesis at the Kempten University of Applied Sciences (Hochschule Kempten).
It was designed to answer the question of whether a modern $1 microcontroller could run a complete open world 3D game.
The thesis is available here and should answer most of the design decisions behind the engine.
Daft-Freak has created a fork using the 32blit SDK available here. It allows the engine to run on different 32blit enabled hardware including single-core STM32 systems and RP2350. Other MCUs may require a 32blit sdk port to run, but this is recommended as the engine might move to it in the future.
Check out the Blender tutorials on creating your own game worlds.
The main.cpp file contains a general overview of the game and engine. The most important Pico3D feature is going to be the render_triangle() function.
This function basically does all of the hard work of transforming a triangle (in world space) and pushing it into the renderer (no deep engine/graphics knowledge needed!).
See the test models and the render_model_16bit functions for an example on how to put in your own meshes.
The rasterizer itself (performance critical code) is contained within render_rasterize.cpp.
The included game has a grid size of 12x12 chunks (each chunk is 10x10m in size -> world size of 120x120m).
Right now the chunk cache uses an 8 bit int for each direction limiting the world size to 256x256 chunks (2.56x2.56km).
This can be extended if needed and the use of a different/modified chunk system can work around the limited storage available on most MCUs.
Right now the game simply simulates all 50 NPCs and 50 zombies at the same time since that is pretty cheap compared to the actual rendering.
It's also more realistic that way and uncovers any big issues in the self-made RNG ;).
Rendering is optimized with distance and view frustum culling.
These show how to make a possible variant of the game for developers: Picocean (picocean branch) - A Wind Waker inspired demo extending the chunk size to 50x50m with a single island while utilizing a fake ocean/horizon. Gamescom (compile define) - This version was used to demonstrate the engine at Gamescom and replaces the zombies with balloons to conform to USK ratings.
The city itself was inspired heavily by Cyberpunk 2077 and the Yakuza series of games. The outskirts have a Legend of Zelda: Breath of the Wild influence.
Divisions are relatively expensive on the RP2040 if performed in quick succession such as when interpolating vertices for mesh blending.
Performance can be tested by changing the NPC or Zombie walk animations to a non power of 2 number such as 127, forcing the compiler to apply actual divisions instead of cheaper bit shifts.
As the compiler does not know during compilation time if a variable will be a power of 2 or not, it will simply apply divisions regardless if the value is not fixed as it is now.
There are likely ways to improve on this code redundancy but I have not taken the time to think of one yet (don't forget, function calls themselves are relatively expensive).