# async fn run() -> Result<(), Box<dyn std::error::Error>> {

use fragmentcolor::{Renderer, Shader, Pass, Frame};

// Example window. We officially support winit.
let window = fragmentcolor::headless_window(800, 600);

// Initializes a renderer and a target compatible with the OS window.
let renderer = Renderer::new();
let target = renderer.create_target(&window).await?;

// You can pass the shader as a source string, file path, or URL:
let circle = Shader::new("./path/to/circle.wgsl")?;
let triangle = Shader::new("https://fragmentcolor.org/shaders/triangle.wgsl")?;
let wgsl = r#"
struct VertexOutput {
    @builtin(position) coords: vec4<f32>,
}

struct MyStruct {
    my_field: vec3<f32>,
}

@group(0) @binding(0)
var<uniform> my_struct: MyStruct;

@group(0) @binding(1)
var<uniform> my_vec2: vec2<f32>;

@vertex
fn vs_main(@builtin(vertex_index) in_vertex_index: u32) -> VertexOutput {
    const vertices = array(
        vec2( -1., -1.),
        vec2(  3., -1.),
        vec2( -1.,  3.)
    );
    return VertexOutput(vec4<f32>(vertices[in_vertex_index], 0.0, 1.0));
}

@fragment
fn fs_main() -> @location(0) vec4<f32> {
    return vec4<f32>(my_struct.my_field, 1.0);
}
"#;

let shader = Shader::new(wgsl)?;

// The library binds and updates the uniforms automatically
shader.set("my_struct.my_field", [0.1f32, 0.8, 0.9])?;
shader.set("my_vec2", [1.0f32, 1.0])?;

// One shader is all you need to render
renderer.render(&shader, &target)?;

// But you can also combine multiple shaders in a render Pass
let pass = Pass::new("single pass");
pass.add_shader(&circle);
pass.add_shader(&triangle);
pass.add_shader(&shader);
renderer.render(&pass, &target)?;

// You can build arbitrary multi-pass graphs by declaring Pass dependencies
let blurx = Pass::new("blur x");
blurx.add_shader(&Shader::new("./shaders/blur_x.wgsl")?);
blurx.require(&pass)?; // pass renders before blurx

// Finally, you can combine multiple passes linearly in a Frame
let frame = Frame::new();
frame.add_pass(pass);
frame.add_pass(Pass::new("GUI pass"));
renderer.render(&frame, &target)?;

// To animate, simply update the uniforms in a loop
for i in 0..10 {
    circle.set("position", [i, i])?;
    renderer.render(&frame, &target)?;
}

# Ok(())
# }
# fn main() -> Result<(), Box<dyn std::error::Error>> { pollster::block_on(run()) }