#import bevy_pbr::{
    forward_io::{VertexOutput, FragmentOutput},
    mesh_view_bindings::view,
}

struct VoluMaterial {
    mesh_translation: vec3<f32>,
    sphere_radius: f32,
    color: vec4<f32>,
}

@group(2) @binding(100)
var<storage, read> volu_material: VoluMaterial;

fn raymarch_hit(position_: vec3<f32>, direction: vec3<f32>) -> bool {
    var position = position_;
    for (var i = 0; i < 200; i++) {
        if sphere_hit(position) {
          return true;
        }
        position += direction * 0.01;
    }
    return false;
}

fn sphere_hit(p: vec3<f32>) -> bool {
    return distance(p, volu_material.mesh_translation) < volu_material.sphere_radius;
}

@fragment
fn fragment(
    in: VertexOutput,
    @builtin(front_facing) is_front: bool,
) -> FragmentOutput {
    let view_direction = normalize(in.world_position.xyz - view.world_position);

    var out: FragmentOutput;
    if (raymarch_hit(in.world_position.xyz, view_direction)) {
      out.color = volu_material.color;
    } else {
      out.color = vec4(1.0, 1.0, 1.0, 0.2);
    }

    return out;
}