thejerf--baijiSteamVR/Source/Core/VideoCommon/VertexShaderGen.h

// Copyright 2008 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

#pragma once

#include "Common/CommonTypes.h"
#include "Common/EnumFormatter.h"

#include "VideoCommon/LightingShaderGen.h"
#include "VideoCommon/ShaderGenCommon.h"

enum class APIType;
enum class TexInputForm : u32;
enum class TexGenType : u32;
enum class SourceRow : u32;
enum class VSExpand : u32;

// TODO should be reordered
enum class ShaderAttrib : u32
{
  Position = 0,
  PositionMatrix = 1,
  Normal = 2,
  Tangent = 3,
  Binormal = 4,
  Color0 = 5,
  Color1 = 6,

  TexCoord0 = 8,
  TexCoord1 = 9,
  TexCoord2 = 10,
  TexCoord3 = 11,
  TexCoord4 = 12,
  TexCoord5 = 13,
  TexCoord6 = 14,
  TexCoord7 = 15
};
template <>
struct fmt::formatter<ShaderAttrib> : EnumFormatter<ShaderAttrib::TexCoord7>
{
  static constexpr array_type names = {
      "Position",    "Position Matrix", "Normal",      "Tangent",     "Binormal",    "Color 0",
      "Color 1",     nullptr,           "Tex Coord 0", "Tex Coord 1", "Tex Coord 2", "Tex Coord 3",
      "Tex Coord 4", "Tex Coord 5",     "Tex Coord 6", "Tex Coord 7"};
  constexpr formatter() : EnumFormatter(names) {}
};
// Intended for offsetting from Color0/TexCoord0
constexpr ShaderAttrib operator+(ShaderAttrib attrib, int offset)
{
  return static_cast<ShaderAttrib>(static_cast<u8>(attrib) + offset);
}

#pragma pack(1)

struct vertex_shader_uid_data
{
  u32 NumValues() const { return sizeof(vertex_shader_uid_data); }
  u32 components : 23;
  u32 numTexGens : 4;
  u32 numColorChans : 2;
  u32 dualTexTrans_enabled : 1;
  VSExpand vs_expand : 2;
  u32 position_has_3_elems : 1;
  // 6 bits (max 63) — widened from 4 once the VR HUD iteration pushed it past 15.
  u32 code_version : 6;

  u16 texcoord_elem_count;      // 2 bits per texcoord input
  u16 texMtxInfo_n_projection;  // Stored separately to guarantee that the texMtxInfo struct is
                                // 8 bits wide

  struct
  {
    TexInputForm inputform : 2;
    TexGenType texgentype : 3;
    SourceRow sourcerow : 5;
    u32 embosssourceshift : 3;
    u32 embosslightshift : 3;
  } texMtxInfo[8];

  struct
  {
    u32 index : 6;
    u32 normalize : 1;
    u32 pad : 1;
  } postMtxInfo[8];

  LightingUidData lighting;
};
#pragma pack()

using VertexShaderUid = ShaderUid<vertex_shader_uid_data>;

struct CustomVertexContents
{
  std::string_view shader = "";
  std::string_view uniforms = "";
};

VertexShaderUid GetVertexShaderUid();
ShaderCode GenerateVertexShaderCode(APIType api_type, const ShaderHostConfig& host_config,
                                    const vertex_shader_uid_data* uid_data,
                                    CustomVertexContents custom_contents);
void WriteVertexBody(APIType api_type, const ShaderHostConfig& host_config,
                     const vertex_shader_uid_data* uid_data, ShaderCode& out);

// True when the VS itself must apply the per-eye VR projection (VK_KHR_multiview /
// GL_OVR_multiview path — no GS stage for triangles). Shared between the specialized
// and uber vertex shader generators so the two can never disagree.
bool UseVRMultiviewVSProjection(APIType api_type, const ShaderHostConfig& host_config);

// Emits the multiview VR position block: declares `bool vr_pos_replaced` and replaces
// o.pos with per-eye clip coordinates selected via gl_ViewIndex (perspective VR,
// head-locked perspective HUD, head-locked 2D, orthographic virtual screen).
// `view_space_pos` is the expression holding the view-space (pre-projection) position.
// Callers must suppress the trailing depth-range/pixel-center fixups and neutralize
// clip distances when `vr_pos_replaced` is true. Mirrors GeometryShaderGen's stereo
// paths — any change here must be kept in sync with the GS.
void GenerateVRMultiviewVSProjection(ShaderCode& out, APIType api_type,
                                     const ShaderHostConfig& host_config,
                                     std::string_view view_space_pos);