types.h

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//
// Copyright 2020 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
//    names, trademarks, service marks, or product names of the Licensor
//    and its affiliates, except as required to comply with Section 4(c) of
//    the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
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// distributed under the Apache License with the above modification is
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#ifndef PXR_IMAGING_HGI_TYPES_H
#define PXR_IMAGING_HGI_TYPES_H

#include "pxr/pxr.h"
#include "pxr/base/gf/vec3i.h"
#include "pxr/imaging/hgi/api.h"
#include <vector>
#include <limits>
#include <stdlib.h>


PXR_NAMESPACE_OPEN_SCOPE

/// \enum HgiFormat
///
/// HgiFormat describes the memory format of image buffers used in Hgi.
/// These formats are closely aligned with HdFormat and allow us to keep Hgi
/// independent of Hd.
///
/// For reference, see:
///   https://www.khronos.org/registry/vulkan/specs/1.1/html/vkspec.html#VkFormat
enum HgiFormat : int
{
    HgiFormatInvalid = -1,

    // UNorm8 - a 1-byte value representing a float between 0 and 1.
    // float value = (unorm / 255.0f);
    HgiFormatUNorm8 = 0,
    HgiFormatUNorm8Vec2,
    /* HgiFormatUNorm8Vec3 */ // Unsupported Metal (MTLPixelFormat)
    HgiFormatUNorm8Vec4,

    // SNorm8 - a 1-byte value representing a float between -1 and 1.
    // float value = max(snorm / 127.0f, -1.0f);
    HgiFormatSNorm8,
    HgiFormatSNorm8Vec2,
    /* HgiFormatSNorm8Vec3 */ // Unsupported Metal (MTLPixelFormat)
    HgiFormatSNorm8Vec4,

    // Float16 - a 2-byte IEEE half-precision float.
    HgiFormatFloat16,
    HgiFormatFloat16Vec2,
    HgiFormatFloat16Vec3,
    HgiFormatFloat16Vec4,

    // Float32 - a 4-byte IEEE float.
    HgiFormatFloat32,
    HgiFormatFloat32Vec2,
    HgiFormatFloat32Vec3,
    HgiFormatFloat32Vec4,

    // Int16 - a 2-byte signed integer
    HgiFormatInt16,
    HgiFormatInt16Vec2,
    HgiFormatInt16Vec3,
    HgiFormatInt16Vec4,

    // UInt16 - a 2-byte unsigned integer
    HgiFormatUInt16,
    HgiFormatUInt16Vec2,
    HgiFormatUInt16Vec3,
    HgiFormatUInt16Vec4,

    // Int32 - a 4-byte signed integer
    HgiFormatInt32,
    HgiFormatInt32Vec2,
    HgiFormatInt32Vec3,
    HgiFormatInt32Vec4,

    // UNorm8 SRGB - a 1-byte value representing a float between 0 and 1.
    // Gamma compression/decompression happens during read/write.
    // Alpha component is linear.
    /* HgiFormatUNorm8srgb */     // Unsupported by OpenGL
    /* HgiFormatUNorm8Vec2srgb */ // Unsupported by OpenGL
    /* HgiFormatUNorm8Vec3srgb */ // Unsupported Metal (MTLPixelFormat)
    HgiFormatUNorm8Vec4srgb,

    // BPTC compressed. 3-component, 4x4 blocks, signed floating-point
    HgiFormatBC6FloatVec3,

    // BPTC compressed. 3-component, 4x4 blocks, unsigned floating-point
    HgiFormatBC6UFloatVec3,

    // BPTC compressed. 4-component, 4x4 blocks, unsigned byte.
    // Representing a float between 0 and 1.
    HgiFormatBC7UNorm8Vec4,

    // BPTC compressed. 4-component, 4x4 blocks, unsigned byte, sRGB.
    // Representing a float between 0 and 1.
    HgiFormatBC7UNorm8Vec4srgb,

    // S3TC/DXT compressed. 4-component, 4x4 blocks, unsigned byte
    // Representing a float between 0 and 1.
    HgiFormatBC1UNorm8Vec4,

    // S3TC/DXT compressed. 4-component, 4x4 blocks, unsigned byte
    // Representing a float between 0 and 1.
    HgiFormatBC3UNorm8Vec4,

    // Depth stencil format (Float32 can be used for just depth)
    HgiFormatFloat32UInt8,

    // Packed 32-bit value with four normalized signed two's complement
    // integer values arranged as 10 bits, 10 bits, 10 bits, and 2 bits.
    HgiFormatPackedInt1010102,

    HgiFormatCount
};

/// \class HgiMipInfo
///
/// HgiMipInfo describes size and other info for a mip level.
struct HgiMipInfo
{
    /// Offset in bytes from start of texture data to start of mip map.
    size_t byteOffset;
    /// Dimension of mip GfVec3i.
    GfVec3i dimensions;
    /// size of (one layer if array of) mip map in bytes.
    size_t byteSizePerLayer;
};

/// Return the count of components in the given format.
HGI_API
size_t HgiGetComponentCount(HgiFormat f);

/// Return the size of a single element of the given format.
///
/// For an uncompressed format, returns the number of bytes per pixel
/// and sets blockWidth and blockHeight to 1.
/// For a compressed format (e.g., BC6), returns the number of bytes per
/// block and sets blockWidth and blockHeight to the width and height of
/// a block.
///
HGI_API
size_t HgiGetDataSizeOfFormat(
    HgiFormat f,
    size_t *blockWidth = nullptr,
    size_t *blockHeight = nullptr);

/// Return whether the given format uses compression.
HGI_API
bool HgiIsCompressed(HgiFormat f);

/// Returns the size necessary to allocate a buffer of given dimensions
/// and format, rounding dimensions up to suitable multiple when
/// using a compressed format.
HGI_API
size_t HgiGetDataSize(
    HgiFormat f,
    const GfVec3i &dimensions);

/// Returns the scalar type of the format, in the form of an HgiFormat, if
/// possible.
HGI_API
HgiFormat HgiGetComponentBaseFormat(
    HgiFormat f);

/// Returns mip infos.
///
/// If dataByteSize is specified, the levels stops when the total memory
/// required by all levels up to that point reach the specified value.
/// Otherwise, the levels stop when all dimensions are 1.
/// Mip map sizes are calculated by dividing the previous mip level by two and
/// rounding down to the nearest integer (minimum integer is 1).
/// level 0: 37x53
/// level 1: 18x26
/// level 2: 9x13
/// level 3: 4x6
/// level 4: 2x3
/// level 5: 1x1
HGI_API
std::vector<HgiMipInfo>
HgiGetMipInfos(
    HgiFormat format,
    const GfVec3i& dimensions,
    size_t layerCount,
    size_t dataByteSize = std::numeric_limits<size_t>::max());

PXR_NAMESPACE_CLOSE_SCOPE

#endif