let mut glfw_ctx = GlfwContext::new(900, 700, false)?;

init(Config::default())?;

let surface = glfw_ctx.create_surface(900, 700, false)?;

let graphics = graphics_create(surface, 900, 700, TextureFormat::Rgba16Float)?;

graphics_mode_3d(graphics)?;

transform_set_position(graphics, Vec3::new(0.0, 4.0, 18.0))?;

transform_look_at(graphics, Vec3::new(0.0, 0.0, 0.0))?;

let _light =

light_create_directional(graphics, bevy::color::Color::srgb(0.95, 0.9, 0.85), 200.0)?;

let source = geometry_sphere(5.0, 32, 24)?;

let position_attr = geometry_attribute_position();

let uv_attr = geometry_attribute_uv();

let color_attr = geometry_attribute_color();

let p = particles_create_from_geometry(source, vec![position_attr, uv_attr, color_attr])?;

let uv_buf = particles_buffer(p, uv_attr)?.ok_or(error::ProcessingError::ParticlesNotFound)?;

let color_buf =

particles_buffer(p, color_attr)?.ok_or(error::ProcessingError::ParticlesNotFound)?;

let uv_bytes = buffer_read(uv_buf)?;

let mut colors: Vec<u8> = Vec::with_capacity(uv_bytes.len() * 2);

for chunk in uv_bytes.chunks_exact(8) {

let u = f32::from_le_bytes([chunk[0], chunk[1], chunk[2], chunk[3]]);

let (r, g, b) = hsv_to_rgb(u, 0.85, 1.0);

for f in [r, g, b, 1.0] {

colors.extend_from_slice(&f.to_le_bytes());

}

}

buffer_write(color_buf, colors)?;

let particle = geometry_sphere(0.18, 10, 8)?;

let mat = {

let m = material_create_pbr()?;

material_set_albedo_buffer(m, color_buf)?;

m

};

let noise = particles_kernel_noise()?;

while glfw_ctx.poll_events() {

graphics_begin_draw(graphics)?;

graphics_record_command(

graphics,

DrawCommand::BackgroundColor(bevy::color::Color::srgb(0.06, 0.06, 0.08)),

)?;

graphics_record_command(graphics, DrawCommand::Material(mat))?;

graphics_record_command(

graphics,

DrawCommand::Particles {

particles: p,

geometry: Some(particle),

topology: Default::default(),

},

)?;

graphics_end_draw(graphics)?;

let t = elapsed_time()?;

compute_set(noise, "scale", shader_value::ShaderValue::Float(0.25))?;

compute_set(noise, "strength", shader_value::ShaderValue::Float(0.02))?;

compute_set(noise, "time", shader_value::ShaderValue::Float(t * 0.5))?;

particles_apply(p, noise)?;

}

Ok(())

let i = (h * 6.0).floor();

let f = h * 6.0 - i;

let p = v * (1.0 - s);

let q = v * (1.0 - f * s);

let t = v * (1.0 - (1.0 - f) * s);

match (i as i32).rem_euclid(6) {

0 => (v, t, p),

1 => (q, v, p),

2 => (p, v, t),

3 => (p, q, v),

4 => (t, p, v),

_ => (v, p, q),

}