SDL_Universe

SDL_Universe is a small and basic software renderer written in C++ with SDL. It is just a hobby project for my own entertainment, but you can use it as you want and contribute to it freely.

Disclaimer

This is purely a hobby project, I started it to learn and experience 3D programming closely. It should not be compared to modern 3D graphic libraries, such as OpenGL or Direct3D. One could see it as a totally needless and unnecessary project, but I want to work on it, so I will. Feature request and improvement suggestions are welcome, but I want to keep the project reasonably simple.

Screenshots

In the screenshots folder with explanations.

Planned (or already implemented) features

Render colored points, lines and filled triangles positioned in 3D space (these are called the "primitives")
SU::Model class to bundle these primitives, also to save and load them via an external file
SU::Object class to create a hierarchy of SU::Models and to transform them, even a full group of them (transforming means to rotate, stretch, move, etc.)
Fast distance-based shorting, optional Z-buffer for pixel-perfect renders
Very basic lighting system (ambiance and global directional light, as well as location based light sources)
"Collision" detectiton, line and triangle cutting appropriately (for example if a line goes through a filled triangle, the line should be cut to 2 pieces)
Documentation
...

"Wishlist" features

Texturing
Multiple backends (immediate OpenGL for example)
A dynamic Level of Detail system (SU::Models have several versions, each detailed a little less, so those far away are rendered with less detail for better performance - and the system does this internally)
Alpha channel for colors (for example half-opaque triangle)
Higher level bodies (sphere, cylinder, cone, etc.) and runtime tessellation
...

What is done

Flag system to toggle features
Can bundle primitives in a SU::Model and render them
Can create tree-like SU::Object hierarchy
All kinds of transformations work and inherit properly
Camera management is fully implemented

Notes and known bugs

The way to display an SDL_Surface with SDL2 is a bit complicated. You need an SDL_Window, an SDL_Renderer for that window, an SDL_Texture to render, and finally an SDL_Surface to create the texture from. It seems that the process of this takes up 9ms on my machine, no matter if I draw 1 single line on a surface or a hundred. I should find a faster way to display a single SDL_Surface in the window when using SDL2.
- Probably SDL_UpdateTexture() is what slows down the process, from 3ms to 10ms latency.
- SDL1 port added for compatibility and performance, see more below
The current implementation is not idiot-proof, use everything as intended. Variable and function names are pretty straightforward, but if something does not work, feel free to ask.

SDL1 vs. SDL2

The library can be compiled with SDL1 or SDL2, because it is only using SDL_Surface, which is the same in both SDL versions. But I think SDL1.2 is superior in this case, because:

it is simpler to get some visuals on the screen (there is no separate renderer, texture, etc., just an SDL_Surface and flipping)
it is faster (everything is on CPU side, so no data transfer between GPU and CPU takes place, which would slow down the process pretty much - as it does when using SDL2)
consumes less CPU time
consumes significantly less memory

These statements are based on my own experience, but there is going to be a more detailed benchmarking after the library is mostly finished.

Licence

Not yet chosen, likely zlib or CC-by.

Contact

You can contact me here on GitHub or via email at iamsemmu AT gmail DOT com

Semmu/sdl_universe

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