src/libANGLE/renderer/Format.h

//
// Copyright 2016 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Format:
//   A universal description of typed GPU storage. Across multiple
//   renderer back-ends, there are common formats and some distinct
//   permutations, this enum encapsulates them all. Formats apply to
//   textures, but could also apply to any typed data.

#ifndef LIBANGLE_RENDERER_FORMAT_H_
#define LIBANGLE_RENDERER_FORMAT_H_

#include "libANGLE/renderer/FormatID_autogen.h"
#include "libANGLE/renderer/renderer_utils.h"

namespace angle
{
enum class FormatID;

extern const Format gFormatInfoTable[];

struct Format final : private angle::NonCopyable
{
    inline constexpr Format(FormatID id,
                            GLenum glFormat,
                            GLenum fboFormat,
                            rx::MipGenerationFunction mipGen,
                            const rx::FastCopyFunctionMap &fastCopyFunctions,
                            rx::PixelReadFunction colorRead,
                            rx::PixelWriteFunction colorWrite,
                            GLenum componentType,
                            GLuint redBits,
                            GLuint greenBits,
                            GLuint blueBits,
                            GLuint alphaBits,
                            GLuint luminanceBits,
                            GLuint depthBits,
                            GLuint stencilBits,
                            GLuint pixelBytes,
                            GLuint componentAlignmentMask,
                            bool isBlock,
                            bool isFixed,
                            bool isScaled,
                            bool isSRGB,
                            bool isYUV,
                            gl::VertexAttribType vertexAttribType);

    static const Format &Get(FormatID id) { return gFormatInfoTable[static_cast<int>(id)]; }

    static FormatID InternalFormatToID(GLenum internalFormat);

    constexpr bool hasDepthOrStencilBits() const;
    constexpr bool hasDepthAndStencilBits() const;
    constexpr bool isLUMA() const;
    constexpr bool isBGRA() const;

    constexpr bool isSint() const;
    constexpr bool isUint() const;
    constexpr bool isSnorm() const;
    constexpr bool isUnorm() const;
    constexpr bool isFloat() const;
    constexpr bool isVertexTypeHalfFloat() const;

    constexpr bool isInt() const { return isSint() || isUint(); }
    constexpr bool isNorm() const { return isSnorm() || isUnorm(); }
    constexpr bool isPureInt() const { return isInt() && !isScaled; }

    bool operator==(const Format &other) const { return this->id == other.id; }

    FormatID id;

    // The closest matching GL internal format for the storage this format uses. Note that this
    // may be a different internal format than the one this ANGLE format is used for.
    GLenum glInternalFormat;

    // The format we should report to the GL layer when querying implementation formats from a FBO.
    // This might not be the same as the glInternalFormat, since some DXGI formats don't have
    // matching GL format enums, like BGRA4, BGR5A1 and B5G6R6.
    GLenum fboImplementationInternalFormat;

    rx::MipGenerationFunction mipGenerationFunction;
    rx::PixelReadFunction pixelReadFunction;
    rx::PixelWriteFunction pixelWriteFunction;

    // A map from a gl::FormatType to a fast pixel copy function for this format.
    const rx::FastCopyFunctionMap &fastCopyFunctions;

    GLenum componentType;

    GLuint redBits;
    GLuint greenBits;
    GLuint blueBits;
    GLuint alphaBits;
    GLuint luminanceBits;
    GLuint depthBits;
    GLuint stencilBits;

    GLuint pixelBytes;

    // For 1-byte components, is 0x0. For 2-byte, is 0x1. For 4-byte, is 0x3. For all others,
    // MAX_UINT.
    GLuint componentAlignmentMask;

    GLuint channelCount;

    bool isBlock;
    bool isFixed;
    bool isScaled;
    bool isSRGB;
    bool isYUV;

    // For vertex formats only. Returns the "type" value for glVertexAttribPointer etc.
    gl::VertexAttribType vertexAttribType;
};

constexpr GLuint GetChannelCount(GLuint redBits,
                                 GLuint greenBits,
                                 GLuint blueBits,
                                 GLuint alphaBits,
                                 GLuint luminanceBits,
                                 GLuint depthBits,
                                 GLuint stencilBits)
{
    return (redBits > 0 ? 1 : 0) + (greenBits > 0 ? 1 : 0) + (blueBits > 0 ? 1 : 0) +
           (alphaBits > 0 ? 1 : 0) + (luminanceBits > 0 ? 1 : 0) + (depthBits > 0 ? 1 : 0) +
           (stencilBits > 0 ? 1 : 0);
}

constexpr Format::Format(FormatID id,
                         GLenum glFormat,
                         GLenum fboFormat,
                         rx::MipGenerationFunction mipGen,
                         const rx::FastCopyFunctionMap &fastCopyFunctions,
                         rx::PixelReadFunction colorRead,
                         rx::PixelWriteFunction colorWrite,
                         GLenum componentType,
                         GLuint redBits,
                         GLuint greenBits,
                         GLuint blueBits,
                         GLuint alphaBits,
                         GLuint luminanceBits,
                         GLuint depthBits,
                         GLuint stencilBits,
                         GLuint pixelBytes,
                         GLuint componentAlignmentMask,
                         bool isBlock,
                         bool isFixed,
                         bool isScaled,
                         bool isSRGB,
                         bool isYUV,
                         gl::VertexAttribType vertexAttribType)
    : id(id),
      glInternalFormat(glFormat),
      fboImplementationInternalFormat(fboFormat),
      mipGenerationFunction(mipGen),
      pixelReadFunction(colorRead),
      pixelWriteFunction(colorWrite),
      fastCopyFunctions(fastCopyFunctions),
      componentType(componentType),
      redBits(redBits),
      greenBits(greenBits),
      blueBits(blueBits),
      alphaBits(alphaBits),
      luminanceBits(luminanceBits),
      depthBits(depthBits),
      stencilBits(stencilBits),
      pixelBytes(pixelBytes),
      componentAlignmentMask(componentAlignmentMask),
      channelCount(GetChannelCount(redBits,
                                   greenBits,
                                   blueBits,
                                   alphaBits,
                                   luminanceBits,
                                   depthBits,
                                   stencilBits)),
      isBlock(isBlock),
      isFixed(isFixed),
      isScaled(isScaled),
      isSRGB(isSRGB),
      isYUV(isYUV),
      vertexAttribType(vertexAttribType)
{}

constexpr bool Format::hasDepthOrStencilBits() const
{
    return depthBits > 0 || stencilBits > 0;
}

constexpr bool Format::hasDepthAndStencilBits() const
{
    return depthBits > 0 && stencilBits > 0;
}

constexpr bool Format::isLUMA() const
{
    // There's no format with G or B without R
    ASSERT(redBits > 0 || (greenBits == 0 && blueBits == 0));
    return redBits == 0 && (luminanceBits > 0 || alphaBits > 0);
}

constexpr bool Format::isBGRA() const
{
    return id == FormatID::B8G8R8A8_UNORM || id == FormatID::B8G8R8A8_UNORM_SRGB ||
           id == FormatID::B8G8R8A8_TYPELESS || id == FormatID::B8G8R8A8_TYPELESS_SRGB;
}

constexpr bool Format::isSint() const
{
    return componentType == GL_INT;
}

constexpr bool Format::isUint() const
{
    return componentType == GL_UNSIGNED_INT;
}

constexpr bool Format::isSnorm() const
{
    return componentType == GL_SIGNED_NORMALIZED;
}

constexpr bool Format::isUnorm() const
{
    return componentType == GL_UNSIGNED_NORMALIZED;
}

constexpr bool Format::isFloat() const
{
    return componentType == GL_FLOAT;
}

constexpr bool Format::isVertexTypeHalfFloat() const
{
    return vertexAttribType == gl::VertexAttribType::HalfFloat;
}

template <typename T>
using FormatMap = PackedEnumMap<FormatID, T, kNumANGLEFormats>;

}  // namespace angle

#endif  // LIBANGLE_RENDERER_FORMAT_H_