////////////////////////////////////////////////////////////
//~ Rect shader

//////////////////////////////
//- Vertex shader

VertexShader(UI_DRectVS, UI_DRectPSInput)
{
  UI_DParams params = G_Dereference<UI_DParams>(UI_ShaderConst_Params)[0];
  StructuredBuffer<UI_DRect> rects = G_Dereference<UI_DRect>(params.rects);
  UI_DRect rect = rects[SV_InstanceID];

  Vec2 rect_uv = RectUvFromVertexId(SV_VertexID);
  Vec2 tex_uv = lerp(rect.tex_slice_uv.p0, rect.tex_slice_uv.p1, rect_uv);
  Vec2 target_pos = lerp(rect.bounds.p0, rect.bounds.p1, rect_uv);

  UI_DRectPSInput result;
  result.sv_position = Vec4(NdcFromPos(target_pos, Vec2(params.target_size).xy), 0, 1);
  result.background_lin = rect.background_lin;
  result.border_lin = rect.border_lin;
  result.tint_lin = rect.tint_lin;
  result.rect_idx = SV_InstanceID;
  result.rect_uv = rect_uv;
  result.tex_uv = tex_uv;

  return result;
}

//////////////////////////////
//- Pixel shader

PixelShader(UI_DRectPS, UI_DRectPSOutput, UI_DRectPSInput input)
{
  UI_DParams params = G_Dereference<UI_DParams>(UI_ShaderConst_Params)[0];
  StructuredBuffer<UI_DRect> rects = G_Dereference<UI_DRect>(params.rects);
  SamplerState sampler = G_Dereference(params.sampler);

  UI_DRect rect = rects[input.rect_idx];

  Vec2 p = input.sv_position.xy;
  Vec2 rect_uv = input.rect_uv;
  Vec2 p0 = rect.bounds.p0;
  Vec2 p1 = rect.bounds.p1;

  // Compute rect sdf (negative means pixel is inside of rect)
  f32 rect_dist = min(min(p.x - p0.x, p1.x - p.x), min(p.y - p0.y, p1.y - p.y));
  {
    f32 tl_radius = rect.tl_rounding;
    f32 tr_radius = rect.tr_rounding;
    f32 br_radius = rect.br_rounding;
    f32 bl_radius = rect.bl_rounding;
    Vec2 tl = Vec2(p0.x + tl_radius, p0.y + tl_radius);
    Vec2 tr = Vec2(p1.x - tr_radius, p0.y + tr_radius);
    Vec2 br = Vec2(p1.x - br_radius, p1.y - br_radius);
    Vec2 bl = Vec2(p0.x + bl_radius, p1.y - bl_radius);
    if (p.x < tl.x && p.y < tl.y) { rect_dist = min(rect_dist, tl_radius - length(tl - p)); }
    if (p.x > tr.x && p.y < tr.y) { rect_dist = min(rect_dist, tr_radius - length(tr - p)); }
    if (p.x > br.x && p.y > br.y) { rect_dist = min(rect_dist, br_radius - length(br - p)); }
    if (p.x < bl.x && p.y > bl.y) { rect_dist = min(rect_dist, bl_radius - length(bl - p)); }
  }
  rect_dist = -rect_dist;

  // Compute border sdf (negative means pixel is inside of border)
  f32 border_width = 0;
  f32 border_dist = 0;
  Vec4 border_color = 0;
  {
    if (rect.border > 0)
    {
      border_width = rect.border;
      border_color = input.border_lin;
    }
    else
    {
      border_width = 0;
      border_color = input.background_lin;
    }
    border_dist = abs(rect_dist);
    if (rect_dist <= 0)
    {
      border_dist -= border_width;
    }
  }

  Vec4 final_color = 0;
  {
    // Background color
    if (G_IsRefNil(rect.tex))
    {
      final_color = input.background_lin;
    }
    else
    {
      Texture2D<Vec4> tex = G_Dereference<Vec4>(rect.tex);
      final_color = tex.Sample(sampler, input.tex_uv);
    }
    final_color *= rect_dist <= 0;

    // Border color
    {
      f32 half_border_dist_fwidth = fwidth_fine(border_dist) * 0.5;
      f32 border_alpha = smoothstep(half_border_dist_fwidth, -half_border_dist_fwidth, border_dist);
      final_color = lerp(final_color, border_color, border_alpha);
    }

    // Tint
    final_color *= input.tint_lin;

    // Debug color
    if (UI_ShaderConst_DebugDraw)
    {
      final_color = rect.debug_lin;
    }
  }

  UI_DRectPSOutput output;
  output.sv_target0 = final_color;
  return output;
}

////////////////////////////////////////////////////////////
//~ Blit shader

//////////////////////////////
//- Vertex shader

VertexShader(UI_BlitVS, UI_BlitPSInput)
{
  Vec2 uv = RectUvFromVertexId(SV_VertexID);
  UI_BlitPSInput result;
  result.sv_position = Vec4(NdcFromUv(uv).xy, 0, 1);
  result.src_uv = uv;

  return result;
}

//////////////////////////////
//- Pixel shader

PixelShader(UI_BlitPS, UI_BlitPSOutput, UI_BlitPSInput input)
{
  UI_DParams params = G_Dereference<UI_DParams>(UI_ShaderConst_Params)[0];
  Texture2D<Vec4> tex = G_Dereference<Vec4>(params.target_ro);
  SamplerState sampler = G_Dereference(params.sampler);

  Vec2 uv = input.src_uv;
  Vec4 result = tex.Sample(sampler, uv);

  UI_BlitPSOutput output;
  output.sv_target0 = result;
  return output;
}