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Why another game library?

These are the times that try men's souls. The harder the conflict, the more glorious the triumph; what we obtain too cheap, we esteem too lightly.

I'm not following...

We're drowning in abstractions and I want out, hombre! Game engines are a kitchen sink full of utencils to help you make the same game that a dozen people have already made, and the rest of us have already played. Delay your gratification, millenial. Let's make games with hand tools again.

You want to get rid of abstractions? I don't see any assembly here.

No, I just want to choose them more carefully. It's the same way I approach alcohol. In my foolish youth I bought Natty Light and Jack Daniels, but now I savor a glass of Woodford Reserve and do various other things that make me better than you.

What can it do?

As little as possible while still being useful. The core abstraction is called an "entity", which is definitely not a horribly overloaded word. It is a bundle of state that lets you draw something. There's a really basic one built in called a TwoDEntity that can draw simple shapes:

# examples/src/ex02_rect.nim

var entity: TwoDEntity

proc init*(game: var Game) =
  doAssert glInit()

  # create a rectangle and put it somewhere
  var uncompiledEntity = initTwoDEntity(primitives.rectangle[GLfloat]())
  uncompiledEntity.project(float(game.frameWidth), float(game.frameHeight))
  uncompiledEntity.translate(50f, 50f)
  uncompiledEntity.scale(100f, 100f)
  uncompiledEntity.color(vec4(1f, 0f, 0f, 1f))

  # compile it so it can be rendered
  entity = compile(game, uncompiledEntity)

proc tick*(game: Game) =
  glClearColor(1f, 1f, 1f, 1f)
  glViewport(0, 0, GLsizei(game.frameWidth), GLsizei(game.frameHeight))
  render(game, entity)

Notice what we don't wrap. There is no need to wrap glInit, glClear, etc. They work fine, why hide them behind a stupid layer?

All that does is draw a red square. What about an image?

There is an ImageEntity for that. You need to use an external library called STB image to load the image:

# examples/src/ex01_image.nim

const image = staticRead("assets/aintgottaexplainshit.jpg")

var entity: ImageEntity

proc init*(game: var Game) =
  doAssert glInit()

    width, height, channels: int
    data: seq[uint8]
  data = stbi.loadFromMemory(cast[seq[uint8]](image), width, height, channels, stbi.RGBA)
  var uncompiledImage = initImageEntity(data, width, height)
  uncompiledImage.project(float(game.frameWidth), float(game.frameHeight))
  uncompiledImage.translate(0f, 0f)
  uncompiledImage.scale(float(width), float(height))
  entity = compile(game, uncompiledImage)

How many can I render at once?

I don't know, try it. At some point you should start using instanced rendering, which lets you draw multiple things with one render call. Both of the above entities have "instanced" versions. For example, you can put a bunch of rectangles together like this:

# examples/src/ex03_rand_rects.nim

var entity: InstancedTwoDEntity

proc init*(game: var Game) =
  doAssert glInit()

  let baseEntity = initTwoDEntity(primitives.rectangle[GLfloat]())
  var uncompiledEntity = initInstancedEntity(baseEntity)

  for _ in 0 ..< 50:
    var e = baseEntity
    e.project(float(game.frameWidth), float(game.frameHeight))
    e.translate(cfloat(rand(game.frameWidth)), cfloat(rand(game.frameHeight)))
    e.scale(cfloat(rand(300)), cfloat(rand(300)))
    e.color(vec4(cfloat(rand(1.0)), cfloat(rand(1.0)), cfloat(rand(1.0)), 1f))

  entity = compile(game, uncompiledEntity)

What if I want to render something that isn't a simple shape or an image? What about 3D?

You can make your own entities. All the 3D examples just make custom entities with the right shaders and attributes/uniforms. See the tutorial for a small example of how to create a custom entity.

Paranim wraps a few other things that are normally hard to do manually. The ex17_perspective_texture_meta_3d example shows how to render to a texture, and the group of examples starting with ex19_spheres_3d show how to create an IndexedEntity (which calls OpenGL's glDrawElements function).

How do I render text?

There is a separate library for that: paratext. See the ex27_text example.

How do I play sounds?

To play wav or mp3 files, you can use parasound. Additionally, you can even produce your own MIDI music with paramidi.

Is there any state management thingy? I want to use an entity component system like all cool people do.

For state management I'm making a separate library (notice a pattern here?) called pararules which is a rules engine for Nim. This is uncharted territory for games but I think it is a more powerful solution compared to the typical ECS. If so, maybe one day it'll go through the same maddening hype cycle that ECSs have gone through. A boy can dream.

Wait, what the hell is a Nim?

A programming language. Like all good things, you probably haven't heard of it. I am mainly using it because it's the only "systems" language with a good AST macro system, which is essential to building a rules engine like pararules.

Rust has macros, no?

Rust has "procedural" macros but they are unhygenic and limited. I get the feeling that it is hard to add a good macro system to a language after it matures...just like it's hard to add a static type system to a dynamic language. A good macro system grows with its language, and ideally is used to implement a large part of the language.

I also don't want to pay Rust's hefty complexity tax just to get rid of that GC. My Rust code would easily be twice as long as my Nim code and far harder to read, write, and refactor. GC will not be the reason you never finish your game — complexity will. Buena suerte, amigo.

What about Vulkan? And WebGPU? And multi-threading?

As my grandma would say, "Don't give in to trend-chasing or mindless dogma that is totally detached from the realities of your problem domain." She said that shit to me when I was like five. True story.

I would like to add an abstraction for whatever replaces OpenGL when the dust settles, but for 99% of you I think OpenGL is still OK. If you are experiencing performance problems, it's probably your fault. And multi-threading is not a silver bullet. You are better off sticking to one thread for as long as you can.

How do I build games for the web?

Paranim supports Emscripten. See the README in the parakeet example game for more on how to build with it. Nim is particularly great for this because its C backend fits Emscripten's tools like a glove. Just be careful...Web browsers and Emscripten add a whole new layer of complexity.


A Nim game library







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