drape/index_storage.cpp


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#include "drape/index_storage.hpp"
#include "drape/gl_functions.hpp"

#include <utility>

namespace dp
{
IndexStorage::IndexStorage()
  : m_size(0)
{}

IndexStorage::IndexStorage(std::vector<uint32_t> && initial)
{
  m_size = (uint32_t)initial.size();
  if (IsSupported32bit())
  {
    m_storage = std::move(initial);
  }
  else
  {
    // We pack 2 uint16_t indices into single m_storage element.
    // Every element of "initial" vector is a single index.
    m_storage.resize(GetStorageSize(m_size));
    for (size_t i = 0; i < initial.size(); i++)
    {
      uint16_t * ptr = reinterpret_cast<uint16_t *>(m_storage.data()) + i;
      *ptr = (uint16_t)initial[i];
    }
  }
}

void IndexStorage::Resize(uint32_t size)
{
  m_size = size;
  m_storage.resize(GetStorageSize(m_size));
}

uint32_t IndexStorage::Size() const
{
  return m_size;
}

void * IndexStorage::GetRaw(uint32_t offsetInElements)
{
  if (IsSupported32bit())
    return &m_storage[offsetInElements];

  return reinterpret_cast<uint16_t *>(m_storage.data()) + offsetInElements;
}

void const * IndexStorage::GetRawConst() const
{
  return static_cast<void const *>(m_storage.data());
}

bool IndexStorage::IsSupported32bit()
{
  // We do not use 32-bit indices now to reduce size of index buffers.
  static bool const supports32Bit = false;//GLFunctions::ExtensionsList.IsSupported(GLExtensionsList::UintIndices);
  return supports32Bit;
}

uint32_t IndexStorage::SizeOfIndex()
{
  return IsSupported32bit() ? sizeof(uint32_t) : sizeof(uint16_t);
}

uint32_t IndexStorage::GetStorageSize(uint32_t elementsCount) const
{
  return IsSupported32bit() ? elementsCount : (elementsCount / 2 + 1);
}
}  // namespace dp