textureUtils.h

//
// Copyright 2020 Pixar
//
// Licensed under the terms set forth in the LICENSE.txt file available at
// https://openusd.org/license.
//
#ifndef PXR_IMAGING_HD_ST_TEXTURE_UTILS_H
#define PXR_IMAGING_HD_ST_TEXTURE_UTILS_H
 
#include "pxr/pxr.h"
#include "pxr/imaging/hdSt/api.h"
 
#include "pxr/imaging/hio/image.h"
 
#include "pxr/imaging/hgi/handle.h"
#include "pxr/imaging/hgi/types.h"
 
#include "pxr/base/arch/align.h"
 
#include <memory>
 
PXR_NAMESPACE_OPEN_SCOPE
 
class Hgi;
using HgiTextureHandle = HgiHandle<class HgiTexture>;
 
class HdStTextureUtils
{
public:
    using ConversionFunction =
        void(*)(const void * src,
                size_t numTexels,
                void * dst);
 
    HDST_API
    static
    HgiFormat GetHgiFormat(
        HioFormat hioFormat,
        bool premultiplyAlpha);
 
    HDST_API
    static
    ConversionFunction GetHioToHgiConversion(
        HioFormat hioFormat,
        bool premultiplyAlpha);
 
    HDST_API
    static
    std::vector<HioImageSharedPtr> GetAllMipImages(
        const std::string &filePath,
        HioImage::SourceColorSpace sourceColorSpace);
 
    // Compute dimensions so that all tiles fit into the given target memory.
    // First by traversing the given images and then by computing a mip chain
    // starting with the lowest resolution image.
    // Optionally, can also give the index of the image in mips that was used
    // to compute the dimensions.
    HDST_API
    static
    GfVec3i
    ComputeDimensionsFromTargetMemory(
        const std::vector<HioImageSharedPtr> &mips,
        HgiFormat targetFormat,
        size_t tileCount,
        size_t targetMemory,
        size_t * mipIndex = nullptr);
 
    // Read given HioImage and convert it to corresponding Hgi format.
    // Returns false if reading the HioImage failed.
    //
    // bufferStart is assumed to point at the beginning of a mip chain
    // with mipInfo describing what mip level of the mip chain to be
    // filled. layer gives the layer number if the mip chain is for an
    // array texture.
    HDST_API
    static
    bool
    ReadAndConvertImage(
        HioImageSharedPtr const &image,
        bool flipped,
        bool premultiplyAlpha,
        const HgiMipInfo &mipInfo,
        size_t layer,
        void * bufferStart);
 
    // Because the underlying graphics API may have alignment
    // restrictions we use this wrapper class to manage the
    // allocation of the returned buffer data, and expose a
    // restricted subset of underlyling pointer's access methods.
    template <typename T>
    class AlignedBuffer
    {
    public:
        AlignedBuffer()
            : AlignedBuffer(nullptr)
            { }
 
        T *get() const {
            return _alignedPtr.get();
        }
 
    private:
        friend class HdStTextureUtils;
 
        explicit AlignedBuffer(T * alignedPtr)
            : _alignedPtr(alignedPtr, ArchAlignedFree)
            { }
 
        T *release() {
            return _alignedPtr.release();
        }
 
        std::unique_ptr<T[], decltype(ArchAlignedFree)*> _alignedPtr;
    };
 
    HDST_API
    static
    AlignedBuffer<uint8_t>
    HgiTextureReadback(Hgi * const hgi,
                       HgiTextureHandle const & texture,
                       size_t * bufferSize);
 
    template <typename T>
    static
    AlignedBuffer<T>
    HgiTextureReadback(Hgi * const hgi,
                       HgiTextureHandle const & texture,
                       size_t * bufferSize);
};
 
template <typename T>
HdStTextureUtils::AlignedBuffer<T>
HdStTextureUtils::HgiTextureReadback(Hgi * const hgi,
                                     HgiTextureHandle const & texture,
                                     size_t * bufferSize)
{
    HdStTextureUtils::AlignedBuffer<uint8_t> buffer =
        HdStTextureUtils::HgiTextureReadback(hgi, texture, bufferSize);
 
    T * typedData = reinterpret_cast<T *>(buffer.release());
    return HdStTextureUtils::AlignedBuffer<T>(typedData);
}
 
PXR_NAMESPACE_CLOSE_SCOPE
 
#endif