If you like this, you may also like my similar project: [raycastlib](https://gitlab.com/drummyfish/raycastlib). These two libraries can very easily be combined together -- here is a proof-of-concept gif (environment rendered with raycastlib, cubes with small3dlib):
- **Different drawing strategies** to choose from: none, z-buffer (none, full, reduced), triangle sorting (back-to-front, fron-to-back with stencil buffer).
- Triangles provide **barycentric coordinates**, thanks to which practically anything that can be achieved with OpenGL can be achieved (texturing, shading, normal-mapping, texture fitering, transparency, PBR, shadow mapping, MIP mapping, ...).
- There is a near plane, but a **proper culling by it (subdividing triangles) is missing**. You can either cull whole triangles completely or "push" them by the near plane. These options are okay when drawing a model not very close to the camera, but e.g. 3D environments may suffer from artifacts.
- Due to the limitations of 32bit integer arithmetics, some types of movement (particularly camera) **may look jerky, and artifact may appear** in specific situations.
For start take a look at the [helloTerminal.c](https://gitlab.com/drummyfish/small3dlib/blob/master/programs/helloTerminal.c) program. It is only a little bit more complex than a simple hello world.
For more see the other examples and **the library code itself**, it is meant to be self-documenting -- you'll find the description of a lot of things at the start of the file.
- Also init screen resolution, either by defining `S3L_RESOLUTION_X` and `S3L_RESOLUTION_Y` (before including the library) or by setting `S3L_resolutionX` and `S3L_resolutionY` variables.
- Your pixel drawing function (`S3L_PIXEL_FUNC`) will mostly be the performance bottleneck, try to make it as fast as possible. The number of pixels is usually much higher than the number of triangles or vertices processed, so you should focus on pixels the most.
- In your `S3L_PIXEL_FUNC`**use a per-triangle cache!** This saves a lot of CPU time. Basically make sure you don't compute per-triangle values per-pixel, but only once, with the first pixel of the triangle. You can do this by remembering the last `triangleID` and only recompute the value when the ID changes. See the examples for how this is done.
- Some things, such as screen resolution, can be specified as static (compile time, can't change during run time) or dynamic. If you can, prefer setting them to static and a power of two (e.g. `#define S3L_RESOLUTION_X 512`) to increase performance!
- Seeing buggy triangles flashing in front of the camera? With the limited 32bit arithmetic far-away things may be overflowing. Try to scale down the scene. If you also don't mind it, set `S3L_STRICT_NEAR_CULLING` to `1` -- this should probably solve it.
- Seeing triangles weirdly deform in front of the camera? Due to the lack of proper near plane culling one of the options (`S3L_STRICT_NEAR_CULLING == 0`) deals with this by pushing the vertices in front of the near plane. To fix this either manually subdivide your model into more triangles or turn on `S3L_STRICT_NEAR_CULLING` (which will however make the close triangles disappear).
- Seeing triangles disappear randomly in sorted modes? This is because the size of the memory for triangle sorting is limited by default -- increase `S3L_MAX_TRIANGLES_DRAWN`.
- Sorted mode sorts triangles before drawing, but sometimes you need to control the drawing order more precisely. This can be done by reordering the objects in the scene list or rendering the scene multiple times without clearing the screen.
