More detailed demos and better doc coverage

[C0D3-M4513R]

Given the following shader, with "sierra::ShaderLanguage::WGSL".
How would I need to adapt the shader, to get it to output a triangle?

The current example is simplistic sure, but it is too simplistic, to be usable.

I thought, that I maybe need to bind my own descriptor, to set the vertex input. I then spent 1-2 hours trying to understand the sierra::descriptors macro code, only to realise, that that is something completely different (for bindings, and sets).
The next day, I looked closer at the wgsl spec and a little at vulkan c code.
That gave me the insight, that I'd need to specifiy the layouts I need in the sierra::pipeline layout.
Now as I am writing this, I would probably also then need to modify the sierra::pass struct, to then actually specify the contents of the locations to the pipeline?

Ontop there is no description, on what the macros do.
That is exspecially true for proc_macro_attributes, since one might want to modify descriptors, the pipline, add pipline inputs and more.

The current state of this library is in my view horrible/unusable for programmers.
vulkano has great examples, but it's types are too complex for me to understand.
With vulkano I was however able to render my own simple shapes, and create circle shaders without a problem.
That is not something, that can be said for this crate.

Most basic programms will at least require a shader such as the one below.
It would go a long way for usablility, if you could provide an example with the next release, and better explain what the macros do.

Looking for 1-2 hours at a single proc-macro, just to understand, that it doesn't do what you want is frustrating.

struct VertexInput {
    [[location(0)]] a_position: vec3<f32>;
    [[location(2)]] a_color: vec4<f32>;
};
struct VertexOutput {
    [[builtin(position)]] Position: vec4<f32>;
    [[location(2)]] v_color: vec4<f32>;
};

[[stage(vertex)]]
fn vs_main(in: VertexInput) -> VertexOutput {
    var output: VertexOutput;
    output.Position=in.a_position;
    output.v_color=in.a_color;
    return output;
}
[[stage(fragment)]]
fn fs_main(in:VertexOutput) -> [[location(0)]] vec4<f32> {
    return in.v_color;
}

EDIT:
As it stands now, I could probably create a different shader for each possible vertex/color combination I need, and be done faster.
Creating the shader source code is simple, since only the vec values would change.
I don't know however if that approach would work at all for even rendering a simple triangle.
I also don't know, if runtime shader compilation is even something, that could be done (because I don't know how you compile the shaders).

[zakarumych]

Well sure, having more demos and examples would be great.
Right now you can use arcana engine as an example of sierra usage.