// G-buffer rasterization shader for CNN v3
// Pass 1: Proxy geometry → MRT (albedo rgba16float, normal_mat rgba16float, depth32)
// Uses GlobalUniforms, ObjectData, ObjectsBuffer from common_uniforms.
// SPHERE objects use ray-sphere impostor (correct silhouette + normal + depth).

#include "common_uniforms"
#include "math/normal"
#include "ray_sphere"

@group(0) @binding(0) var<uniform> globals: GlobalUniforms;
@group(0) @binding(1) var<storage, read> object_data: ObjectsBuffer;

struct VertexOutput {
    @builtin(position)              position:       vec4f,
    @location(0)                    world_pos:      vec3f,
    @location(1)                    world_normal:   vec3f,
    @location(2)                    color:          vec4f,
    @location(3) @interpolate(flat) instance_index: u32,
}

@vertex
fn vs_main(
    @builtin(vertex_index)   vertex_index:   u32,
    @builtin(instance_index) instance_index: u32
) -> VertexOutput {
    // Proxy box vertices (same as renderer_3d.wgsl)
    var pos = array<vec3f, 36>(
        vec3f(-1.0, -1.0,  1.0), vec3f( 1.0, -1.0,  1.0), vec3f( 1.0,  1.0,  1.0),
        vec3f(-1.0, -1.0,  1.0), vec3f( 1.0,  1.0,  1.0), vec3f(-1.0,  1.0,  1.0),
        vec3f(-1.0, -1.0, -1.0), vec3f(-1.0,  1.0, -1.0), vec3f( 1.0,  1.0, -1.0),
        vec3f(-1.0, -1.0, -1.0), vec3f( 1.0,  1.0, -1.0), vec3f( 1.0, -1.0, -1.0),
        vec3f(-1.0,  1.0, -1.0), vec3f(-1.0,  1.0,  1.0), vec3f( 1.0,  1.0,  1.0),
        vec3f(-1.0,  1.0, -1.0), vec3f( 1.0,  1.0,  1.0), vec3f( 1.0,  1.0, -1.0),
        vec3f(-1.0, -1.0, -1.0), vec3f( 1.0, -1.0, -1.0), vec3f( 1.0, -1.0,  1.0),
        vec3f(-1.0, -1.0, -1.0), vec3f( 1.0, -1.0,  1.0), vec3f(-1.0, -1.0,  1.0),
        vec3f( 1.0, -1.0, -1.0), vec3f( 1.0,  1.0, -1.0), vec3f( 1.0,  1.0,  1.0),
        vec3f( 1.0, -1.0, -1.0), vec3f( 1.0,  1.0,  1.0), vec3f( 1.0, -1.0,  1.0),
        vec3f(-1.0, -1.0, -1.0), vec3f(-1.0, -1.0,  1.0), vec3f(-1.0,  1.0,  1.0),
        vec3f(-1.0, -1.0, -1.0), vec3f(-1.0,  1.0,  1.0), vec3f(-1.0,  1.0, -1.0)
    );

    // Proxy face normals (one per 2 triangles = 6 faces × 6 verts = 36)
    var nrm = array<vec3f, 36>(
        vec3f(0,0,1), vec3f(0,0,1), vec3f(0,0,1),
        vec3f(0,0,1), vec3f(0,0,1), vec3f(0,0,1),
        vec3f(0,0,-1), vec3f(0,0,-1), vec3f(0,0,-1),
        vec3f(0,0,-1), vec3f(0,0,-1), vec3f(0,0,-1),
        vec3f(0,1,0), vec3f(0,1,0), vec3f(0,1,0),
        vec3f(0,1,0), vec3f(0,1,0), vec3f(0,1,0),
        vec3f(0,-1,0), vec3f(0,-1,0), vec3f(0,-1,0),
        vec3f(0,-1,0), vec3f(0,-1,0), vec3f(0,-1,0),
        vec3f(1,0,0), vec3f(1,0,0), vec3f(1,0,0),
        vec3f(1,0,0), vec3f(1,0,0), vec3f(1,0,0),
        vec3f(-1,0,0), vec3f(-1,0,0), vec3f(-1,0,0),
        vec3f(-1,0,0), vec3f(-1,0,0), vec3f(-1,0,0)
    );

    let obj = object_data.objects[instance_index];
    let p = pos[vertex_index];
    let n = nrm[vertex_index];

    let world_pos    = obj.model * vec4f(p, 1.0);
    let clip_pos     = globals.view_proj * world_pos;
    // Transform normal: use model matrix (correct for uniform scale + rotation).
    let world_normal = normalize((obj.model * vec4f(n, 0.0)).xyz);

    var out: VertexOutput;
    out.position       = clip_pos;
    out.world_pos      = world_pos.xyz;
    out.world_normal   = world_normal;
    out.color          = obj.color;
    out.instance_index = instance_index;
    return out;
}

struct GBufOutput {
    @location(0)            albedo:     vec4f,  // rgba16float: material color
    @location(1)            normal_mat: vec4f,  // rgba16float: oct-normal XY in RG, mat_id/255 in B
    @builtin(frag_depth)    depth:      f32,    // corrected depth (sphere impostor)
}

@fragment
fn fs_main(in: VertexOutput) -> GBufOutput {
    let obj      = object_data.objects[in.instance_index];
    let obj_type = u32(obj.params.x);
    let mat_id   = f32(in.instance_index) / 255.0;

    var world_normal = normalize(in.world_normal);
    var frag_depth   = in.position.z;  // default: hardware depth

    // Sphere impostor: ray-sphere intersection for correct silhouette and normal.
    if (obj_type == 1u) {
        let sphere_center = obj.model[3].xyz;
        let sphere_radius = length(obj.model[0].xyz);  // uniform scale in col0
        let cam_pos = globals.camera_pos_time.xyz;
        let rd = normalize(in.world_pos - cam_pos);
        let isect = ray_sphere_intersection(cam_pos, rd, sphere_center, sphere_radius);
        if (!isect.hit) { discard; }
        let hit = cam_pos + rd * isect.t;
        world_normal = normalize(hit - sphere_center);
        // Reproject hit point to get correct clip-space depth.
        let clip_hit = globals.view_proj * vec4f(hit, 1.0);
        frag_depth   = clip_hit.z / clip_hit.w;
    }

    let oct = oct_encode_unorm(world_normal);

    var out: GBufOutput;
    out.albedo     = vec4f(in.color.rgb, 1.0);
    out.normal_mat = vec4f(oct.x, oct.y, mat_id, 0.0);
    out.depth      = frag_depth;
    return out;
}