#pragma BLENDER_REQUIRE(common_math_lib.glsl)
#pragma BLENDER_REQUIRE(gpu_shader_codegen_lib.glsl)
#pragma BLENDER_REQUIRE(eevee_nodetree_lib.glsl)

#if defined(USE_BARYCENTRICS) && defined(GPU_FRAGMENT_SHADER) && defined(MAT_GEOM_MESH)
vec3 barycentric_distances_get()
{
  /* NOTE: No need to undo perspective divide since it has not been applied. */
  vec3 pos0 = (ProjectionMatrixInverse * gpu_position_at_vertex(0)).xyz;
  vec3 pos1 = (ProjectionMatrixInverse * gpu_position_at_vertex(1)).xyz;
  vec3 pos2 = (ProjectionMatrixInverse * gpu_position_at_vertex(2)).xyz;
  vec3 edge21 = pos2 - pos1;
  vec3 edge10 = pos1 - pos0;
  vec3 edge02 = pos0 - pos2;
  vec3 d21 = safe_normalize(edge21);
  vec3 d10 = safe_normalize(edge10);
  vec3 d02 = safe_normalize(edge02);
  vec3 dists;
  float d = dot(d21, edge02);
  dists.x = sqrt(dot(edge02, edge02) - d * d);
  d = dot(d02, edge10);
  dists.y = sqrt(dot(edge10, edge10) - d * d);
  d = dot(d10, edge21);
  dists.z = sqrt(dot(edge21, edge21) - d * d);
  return dists.xyz;
}
#endif

void init_globals_mesh()
{
#if defined(USE_BARYCENTRICS) && defined(GPU_FRAGMENT_SHADER) && defined(MAT_GEOM_MESH)
  g_data.barycentric_coords = gpu_BaryCoord.xy;
  g_data.barycentric_dists = barycentric_distances_get();
#endif
}

void init_globals_curves()
{
  /* Shade as a cylinder. */
  float cos_theta = interp.curves_time_width / interp.curves_thickness;
  float sin_theta = sqrt(max(0.0, 1.0 - cos_theta * cos_theta));
  g_data.N = normalize(interp.N * sin_theta + interp.curves_binormal * cos_theta);

  /* Costly, but follows cycles per pixel tangent space (not following curve shape). */
  vec3 V = cameraVec(g_data.P);
  g_data.curve_T = -interp.curves_tangent;
  g_data.curve_B = cross(V, g_data.curve_T);
  g_data.curve_N = safe_normalize(cross(g_data.curve_T, g_data.curve_B));

  g_data.is_strand = true;
  g_data.hair_time = interp.curves_time;
  g_data.hair_thickness = interp.curves_thickness;
  g_data.hair_strand_id = interp.curves_strand_id;
#if defined(USE_BARYCENTRICS) && defined(GPU_FRAGMENT_SHADER) && defined(MAT_GEOM_CURVES)
  g_data.barycentric_coords = hair_resolve_barycentric(interp.barycentric_coords);
#endif
}

void init_globals_gpencil()
{
  /* Undo backface flip as the gpencil normal is already pointing towards the camera. */
  g_data.N = interp.N;
}

void init_globals()
{
  /* Default values. */
  g_data.P = interp.P;
  g_data.N = safe_normalize(interp.N);
  g_data.Ng = g_data.N;
  g_data.is_strand = false;
  g_data.hair_time = 0.0;
  g_data.hair_thickness = 0.0;
  g_data.hair_strand_id = 0;
  g_data.ray_type = RAY_TYPE_CAMERA; /* TODO */
  g_data.ray_depth = 0.0;
  g_data.ray_length = distance(g_data.P, cameraPos);
  g_data.barycentric_coords = vec2(0.0);
  g_data.barycentric_dists = vec3(0.0);

#ifdef GPU_FRAGMENT_SHADER
  g_data.N = (FrontFacing) ? g_data.N : -g_data.N;
  g_data.Ng = safe_normalize(cross(dFdx(g_data.P), dFdy(g_data.P)));
#endif

#if defined(MAT_GEOM_MESH)
  init_globals_mesh();
#elif defined(MAT_GEOM_CURVES)
  init_globals_curves();
#elif defined(MAT_GEOM_GPENCIL)
  init_globals_gpencil();
#endif
}

/* Avoid some compiler issue with non set interface parameters. */
void init_interface()
{
#ifdef GPU_VERTEX_SHADER
  interp.P = vec3(0.0);
  interp.N = vec3(0.0);
  interp.barycentric_coords = vec2(0.0);
  interp.curves_tangent = vec3(0.0);
  interp.curves_binormal = vec3(0.0);
  interp.curves_time = 0.0;
  interp.curves_time_width = 0.0;
  interp.curves_thickness = 0.0;
  interp.curves_strand_id = 0;
  drw_ResourceID_iface.resource_index = resource_id;
#endif
}