dolphin/Source/Core/VideoCommon/ShaderGenCommon.h

// Copyright 2012 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#pragma once

#include <cstdarg>
#include <cstring>
#include <map>
#include <string>
#include <vector>

#include "Common/CommonTypes.h"
#include "Common/StringUtil.h"
#include "VideoCommon/VideoCommon.h"
#include "VideoCommon/VideoConfig.h"

/**
 * Common interface for classes that need to go through the shader generation path
 * (GenerateVertexShader, GenerateGeometryShader, GeneratePixelShader)
 * In particular, this includes the shader code generator (ShaderCode).
 * A different class (ShaderUid) can be used to uniquely identify each ShaderCode object.
 * More interesting things can be done with this, e.g. ShaderConstantProfile checks what shader
 * constants are being used. This can be used to optimize buffer management.
 * If the class does not use one or more of these methods (e.g. Uid class does not need code), the
 * method will be defined as a no-op by the base class, and the call
 * should be optimized out. The reason for this implementation is so that shader
 * selection/generation can be done in two passes, with only a cache lookup being
 * required if the shader has already been generated.
 */
class ShaderGeneratorInterface
{
public:
  /*
   * Used when the shader generator would write a piece of ShaderCode.
   * Can be used like printf.
   * @note In the ShaderCode implementation, this does indeed write the parameter string to an
   * internal buffer. However, you're free to do whatever you like with the parameter.
   */
  void Write(const char*, ...)
#ifdef __GNUC__
      __attribute__((format(printf, 2, 3)))
#endif
  {
  }

  /*
   * Tells us that a specific constant range (including last_index) is being used by the shader
   */
  void SetConstantsUsed(unsigned int first_index, unsigned int last_index) {}
  /*
   * Returns a pointer to an internally stored object of the uid_data type.
   * @warning since most child classes use the default implementation you shouldn't access this
   * directly without adding precautions against nullptr access (e.g. via adding a dummy structure,
   * cf. the vertex/pixel shader generators)
   */
  template <class uid_data>
  uid_data* GetUidData()
  {
    return nullptr;
  }
};

/*
 * Shader UID class used to uniquely identify the ShaderCode output written in the shader generator.
 * uid_data can be any struct of parameters that uniquely identify each shader code output.
 * Unless performance is not an issue, uid_data should be tightly packed to reduce memory footprint.
 * Shader generators will write to specific uid_data fields; ShaderUid methods will only read raw
 * u32 values from a union.
 * NOTE: Because LinearDiskCache reads and writes the storage associated with a ShaderUid instance,
 * ShaderUid must be trivially copyable.
 */
template <class uid_data>
class ShaderUid : public ShaderGeneratorInterface
{
public:
  bool operator==(const ShaderUid& obj) const
  {
    return memcmp(this->values, obj.values, data.NumValues() * sizeof(*values)) == 0;
  }

  bool operator!=(const ShaderUid& obj) const
  {
    return memcmp(this->values, obj.values, data.NumValues() * sizeof(*values)) != 0;
  }

  // determines the storage order inside STL containers
  bool operator<(const ShaderUid& obj) const
  {
    return memcmp(this->values, obj.values, data.NumValues() * sizeof(*values)) < 0;
  }

  template <class uid_data2>
  uid_data2* GetUidData()
  {
    return &data;
  }
  const uid_data* GetUidData() const { return &data; }
  const u8* GetUidDataRaw() const { return &values[0]; }
  size_t GetUidDataSize() const { return sizeof(values); }
private:
  union
  {
    uid_data data;
    u8 values[sizeof(uid_data)];
  };
};

class ShaderCode : public ShaderGeneratorInterface
{
public:
  ShaderCode() { m_buffer.reserve(16384); }
  const std::string& GetBuffer() const { return m_buffer; }
  void Write(const char* fmt, ...)
#ifdef __GNUC__
      __attribute__((format(printf, 2, 3)))
#endif
  {
    va_list arglist;
    va_start(arglist, fmt);
    m_buffer += StringFromFormatV(fmt, arglist);
    va_end(arglist);
  }

protected:
  std::string m_buffer;
};

/**
 * Generates a shader constant profile which can be used to query which constants are used in a
 * shader
 */
class ShaderConstantProfile : public ShaderGeneratorInterface
{
public:
  ShaderConstantProfile(int num_constants) { constant_usage.resize(num_constants); }
  void SetConstantsUsed(unsigned int first_index, unsigned int last_index)
  {
    for (unsigned int i = first_index; i < last_index + 1; ++i)
      constant_usage[i] = true;
  }

  bool ConstantIsUsed(unsigned int index) const
  {
    // TODO: Not ready for usage yet
    return true;
    // return constant_usage[index];
  }

private:
  std::vector<bool> constant_usage;  // TODO: Is vector<bool> appropriate here?
};

template <class T>
inline void DefineOutputMember(T& object, APIType api_type, const char* qualifier, const char* type,
                               const char* name, int var_index, const char* semantic = "",
                               int semantic_index = -1)
{
  object.Write("\t%s %s %s", qualifier, type, name);

  if (var_index != -1)
    object.Write("%d", var_index);

  if (api_type == APIType::D3D && strlen(semantic) > 0)
  {
    if (semantic_index != -1)
      object.Write(" : %s%d", semantic, semantic_index);
    else
      object.Write(" : %s", semantic);
  }

  object.Write(";\n");
}

template <class T>
inline void GenerateVSOutputMembers(T& object, APIType api_type, u32 texgens,
                                    bool per_pixel_lighting, const char* qualifier)
{
  DefineOutputMember(object, api_type, qualifier, "float4", "pos", -1, "POSITION");
  DefineOutputMember(object, api_type, qualifier, "float4", "colors_", 0, "COLOR", 0);
  DefineOutputMember(object, api_type, qualifier, "float4", "colors_", 1, "COLOR", 1);

  for (unsigned int i = 0; i < texgens; ++i)
    DefineOutputMember(object, api_type, qualifier, "float3", "tex", i, "TEXCOORD", i);

  DefineOutputMember(object, api_type, qualifier, "float4", "clipPos", -1, "TEXCOORD", texgens);

  if (per_pixel_lighting)
  {
    DefineOutputMember(object, api_type, qualifier, "float3", "Normal", -1, "TEXCOORD",
                       texgens + 1);
    DefineOutputMember(object, api_type, qualifier, "float3", "WorldPos", -1, "TEXCOORD",
                       texgens + 2);
  }

  DefineOutputMember(object, api_type, qualifier, "float", "clipDist", 0, "SV_ClipDistance", 0);
  DefineOutputMember(object, api_type, qualifier, "float", "clipDist", 1, "SV_ClipDistance", 1);
}

template <class T>
inline void AssignVSOutputMembers(T& object, const char* a, const char* b, u32 texgens,
                                  bool per_pixel_lighting)
{
  object.Write("\t%s.pos = %s.pos;\n", a, b);
  object.Write("\t%s.colors_0 = %s.colors_0;\n", a, b);
  object.Write("\t%s.colors_1 = %s.colors_1;\n", a, b);

  for (unsigned int i = 0; i < texgens; ++i)
    object.Write("\t%s.tex%d = %s.tex%d;\n", a, i, b, i);

  object.Write("\t%s.clipPos = %s.clipPos;\n", a, b);

  if (per_pixel_lighting)
  {
    object.Write("\t%s.Normal = %s.Normal;\n", a, b);
    object.Write("\t%s.WorldPos = %s.WorldPos;\n", a, b);
  }

  object.Write("\t%s.clipDist0 = %s.clipDist0;\n", a, b);
  object.Write("\t%s.clipDist1 = %s.clipDist1;\n", a, b);
}

// We use the flag "centroid" to fix some MSAA rendering bugs. With MSAA, the
// pixel shader will be executed for each pixel which has at least one passed sample.
// So there may be rendered pixels where the center of the pixel isn't in the primitive.
// As the pixel shader usually renders at the center of the pixel, this position may be
// outside the primitive. This will lead to sampling outside the texture, sign changes, ...
// As a workaround, we interpolate at the centroid of the coveraged pixel, which
// is always inside the primitive.
// Without MSAA, this flag is defined to have no effect.
inline const char* GetInterpolationQualifier(bool msaa, bool ssaa,
                                             bool in_glsl_interface_block = false, bool in = false)
{
  if (!msaa)
    return "";

  // Without GL_ARB_shading_language_420pack support, the interpolation qualifier must be
  // "centroid in" and not "centroid", even within an interface block.
  if (in_glsl_interface_block && !g_ActiveConfig.backend_info.bSupportsBindingLayout)
  {
    if (!ssaa)
      return in ? "centroid in" : "centroid out";
    else
      return in ? "sample in" : "sample out";
  }
  else
  {
    if (!ssaa)
      return "centroid";
    else
      return "sample";
  }
}

// Constant variable names
#define I_COLORS "color"
#define I_KCOLORS "k"
#define I_ALPHA "alphaRef"
#define I_TEXDIMS "texdim"
#define I_ZBIAS "czbias"
#define I_INDTEXSCALE "cindscale"
#define I_INDTEXMTX "cindmtx"
#define I_FOGCOLOR "cfogcolor"
#define I_FOGI "cfogi"
#define I_FOGF "cfogf"
#define I_ZSLOPE "czslope"
#define I_EFBSCALE "cefbscale"

#define I_POSNORMALMATRIX "cpnmtx"
#define I_PROJECTION "cproj"
#define I_MATERIALS "cmtrl"
#define I_LIGHTS "clights"
#define I_TEXMATRICES "ctexmtx"
#define I_TRANSFORMMATRICES "ctrmtx"
#define I_NORMALMATRICES "cnmtx"
#define I_POSTTRANSFORMMATRICES "cpostmtx"
#define I_PIXELCENTERCORRECTION "cpixelcenter"

#define I_STEREOPARAMS "cstereo"
#define I_LINEPTPARAMS "clinept"
#define I_TEXOFFSET "ctexoffset"

static const char s_shader_uniforms[] = "\tfloat4 " I_POSNORMALMATRIX "[6];\n"
                                        "\tfloat4 " I_PROJECTION "[4];\n"
                                        "\tint4 " I_MATERIALS "[4];\n"
                                        "\tLight " I_LIGHTS "[8];\n"
                                        "\tfloat4 " I_TEXMATRICES "[24];\n"
                                        "\tfloat4 " I_TRANSFORMMATRICES "[64];\n"
                                        "\tfloat4 " I_NORMALMATRICES "[32];\n"
                                        "\tfloat4 " I_POSTTRANSFORMMATRICES "[64];\n"
                                        "\tfloat4 " I_PIXELCENTERCORRECTION ";\n";