Note: If you are reading this on Github, please not that this is only a mirror
repository and the newest code is hosted on my mercurial repository at
https://hg.basx.dev/games/semicongine/.

# Semicongine

Hi there

This is a little game engine, mainly trying to wrap around vulkan and the
operating system's windowing, input and audio system. I am using the last
programming language you will ever need, [Nim](https://nim-lang.org/)

## Features

The engine currently features the following:

- No dependencies outside of this repo (except zip/unzip on Linux). All
  dependencies are included (`libs` for library dependencies, `tools` for
  binaries/scripts, `semicongine/thirdparty` for code dependencies)
- Low-level, Vulkan-base rendering system
- All vertex/uniform/descriptors/shader-formats can and must be defined
  "freely". The only restriction that we currently have, is that vertex data is
  non-interleaved.
- A ton of compiletime checks to ensure the defined mesh-data and shaders are
  compatible for rendering
- Simple audio mixer, should suffice for most things
- Simple input-system, no controller support at this time
- Resource packaging of images, audio and 3D files as either folders, zip files or embedded in the executable
- Simple font and text rendering
- A few additional utils like a simple storage API, a few algorithms for
  collision detection, noise generation and texture packing, and a simple
  settings API with hot-reloading

## Hello world example

Attention, this project is not optimized for "hello world"-scenarios, so you
have quite a few lines to get something to display:

```nim

import semicongine

# required
InitVulkan()

# set up a simple render pass to render the displayed frame
var renderpass = CreateDirectPresentationRenderPass(depthBuffer = false, samples = VK_SAMPLE_COUNT_1_BIT)

# the swapchain, needs to be attached to the main renderpass
SetupSwapchain(renderpass = renderpass)

# render data is used for memory management on the GPU
var renderdata = InitRenderData()

type
  # define a push constant, to have something moving
  PushConstant = object
    scale: float32
  # This is how we define shaders: the interface needs to be "typed"
  # but the shader code itself can freely be written in glsl
  Shader = object
    position {.VertexAttribute.}: Vec3f
    color {.VertexAttribute.}: Vec3f
    pushConstant {.PushConstantAttribute.}: PushConstant
    fragmentColor {.Pass.}: Vec3f
    outColor {.ShaderOutput.}: Vec4f
    # code
    vertexCode: string = """void main() {
    fragmentColor = color;
    gl_Position = vec4(position * pushConstant.scale, 1);}"""
    fragmentCode: string = """void main() {
    outColor = vec4(fragmentColor, 1);}"""
  # And we also need to define our Mesh, which does describe the vertex layout
  TriangleMesh = object
    position: GPUArray[Vec3f, VertexBuffer]
    color: GPUArray[Vec3f, VertexBuffer]

# instantiate the mesh and fill with data
var mesh = TriangleMesh(
  position: asGPUArray([NewVec3f(-0.5, -0.5), NewVec3f(0, 0.5), NewVec3f(0.5, -0.5)], VertexBuffer),
  color: asGPUArray([NewVec3f(0, 0, 1), NewVec3f(0, 1, 0), NewVec3f(1, 0, 0)], VertexBuffer),
)

# this allocates GPU data, uploads the data to the GPU and flushes any thing that is host-cached
# this is a shortcut version, more fine-grained control is possible
AssignBuffers(renderdata, mesh)
renderdata.FlushAllMemory()

# Now we need to instantiate the shader as a pipeline object that is attached to a renderpass
var pipeline = CreatePipeline[Shader](renderPass = vulkan.swapchain.renderPass)

# the main render-loop will exit if we get a kill-signal from the OS
while UpdateInputs():

  # starts the drawing for the next frame and provides us necesseary framebuffer and commandbuffer objects in this scope
  WithNextFrame(framebuffer, commandbuffer):

    # start the main (and only) renderpass we have, needs to know the target framebuffer and a commandbuffer
    WithRenderPass(vulkan.swapchain.renderPass, framebuffer, commandbuffer, vulkan.swapchain.width, vulkan.swapchain.height, NewVec4f(0, 0, 0, 0)):

      # now activate our shader-pipeline
      WithPipeline(commandbuffer, pipeline):

        # and finally, draw the mesh and set a single parameter
        # more complicated setups with descriptors/uniforms are of course possible
        RenderWithPushConstant(commandbuffer = commandbuffer, pipeline = pipeline, mesh = mesh, pushConstant = PushConstant(scale: 0.3))

# cleanup
checkVkResult vkDeviceWaitIdle(vulkan.device)
DestroyPipeline(pipeline)
DestroyRenderData(renderdata)
vkDestroyRenderPass(vulkan.device, renderpass.vk, nil)
DestroyVulkan()

```

## Future development

For now all features that I need are implemented. I will gradually add more
stuff that I need, based on the games that I am developing. Here are a few
things that I consider integrating at a later point, once I have gather some
more experience what can/should be used across different projects:

- [ ] More support for glTF format (JPEG textures, animations, morphing)
- [ ] Some often used utils like camera-controllers, offscreen-rendering, shadow-map rendering, etc.
- [ ] Some UI-stuff
- [ ] Controller support