// CNN v2 Static Features Compute Shader
// Generates 8D parametric features: [p0, p1, p2, p3, uv.x, uv.y, sin20_y, bias]
// p0-p3: Parametric features from specified mip level (0=mip0, 1=mip1, 2=mip2, 3=mip3)
// Note: Input image RGBD (mip0) fed separately to Layer 0
//
// TODO: Binary format should support arbitrary layout and ordering for feature vector (7D).
//       Current layout is hardcoded. Future versions should allow runtime-specified
//       feature combinations (e.g., [R, G, B, dx, dy, uv_x, bias] or custom encodings).

struct StaticFeatureParams {
  mip_level: u32,
  padding0: u32,
  padding1: u32,
  padding2: u32,
}

@group(0) @binding(0) var input_tex: texture_2d<f32>;
@group(0) @binding(1) var input_tex_mip1: texture_2d<f32>;
@group(0) @binding(2) var input_tex_mip2: texture_2d<f32>;
@group(0) @binding(3) var depth_tex: texture_2d<f32>;
@group(0) @binding(4) var output_tex: texture_storage_2d<rgba32uint, write>;
@group(0) @binding(5) var<uniform> params: StaticFeatureParams;

@compute @workgroup_size(8, 8)
fn main(@builtin(global_invocation_id) id: vec3<u32>) {
  let coord = vec2<i32>(id.xy);
  let dims = textureDimensions(input_tex);

  if (coord.x >= i32(dims.x) || coord.y >= i32(dims.y)) {
    return;
  }

  // Parametric features (p0-p3) - sample from specified mip level
  var rgba: vec4<f32>;
  if (params.mip_level == 0u) {
    rgba = textureLoad(input_tex, coord, 0);
  } else if (params.mip_level == 1u) {
    rgba = textureLoad(input_tex_mip1, coord, 0);
  } else if (params.mip_level == 2u) {
    rgba = textureLoad(input_tex_mip2, coord, 0);
  } else {
    // Mip 3 or higher: use mip 2 as fallback
    rgba = textureLoad(input_tex_mip2, coord, 0);
  }

  let p0 = rgba.r;
  let p1 = rgba.g;
  let p2 = rgba.b;
  let p3 = textureLoad(depth_tex, coord, 0).r;

  // UV coordinates (normalized [0,1], top-left origin - matches training)
  let uv_x = f32(coord.x) / f32(dims.x);
  let uv_y = f32(coord.y) / f32(dims.y);

  // Multi-frequency position encoding
  let sin20_y = sin(20.0 * uv_y);

  // Bias dimension (always 1.0)
  let bias = 1.0;

  // Pack 8×f16 into 4×u32 (rgba32uint)
  // [p0, p1, p2, p3, uv_x, uv_y, sin20_y, bias]
  let packed = vec4<u32>(
    pack2x16float(vec2<f32>(p0, p1)),
    pack2x16float(vec2<f32>(p2, p3)),
    pack2x16float(vec2<f32>(uv_x, uv_y)),
    pack2x16float(vec2<f32>(sin20_y, bias))
  );

  textureStore(output_tex, coord, packed);
}