Method UpdateMipMaps

trinity/Tr2TextureAtlas.cpp:1449–1553

Call this manually to update mipmaps when appropriate

//Call this manually to update mipmaps when appropriate
void Tr2TextureAtlas::UpdateMipMaps( Tr2RenderContext& renderContext )
{
	CCP_STATS_ZONE( __FUNCTION__ );

	if( !m_hasMipMaps || m_dirtyMipRegions.empty() )
	{
		return;
	}
	if( m_format != Tr2RenderContextEnum::PIXEL_FORMAT_B8G8R8A8_UNORM )
	{
		CCP_LOGERR( "Texture format not supported for mipmapped atlases: %08x [%d]", int( m_format ), int( m_format ) );
		m_dirtyMipRegions.clear();
		return;
	}

	if( !m_texture.IsValid() )
	{
		m_dirtyMipRegions.clear();
		return;
	}

	// Get a copy of the first mip level into system memory
	uint32_t sourcePitch;
	const void* sourceData;
	if( FAILED( m_texture.MapForReading( Tr2TextureSubresource( 0 ), sourceData, sourcePitch, renderContext ) ) )
	{
		CCP_LOGERR( "Tr2TextureAtlas::UpdateMipMaps: Failed to read texture" );
		return;
	}
	std::vector<unsigned char> buffer0( m_texture.GetMipSize( 0 ) );
	const unsigned char* row = reinterpret_cast<const unsigned char*>( sourceData );
	auto destRow = buffer0.begin();
	for( unsigned i = 0; i < m_texture.GetHeight(); ++i )
	{
		std::copy( row, row + m_texture.GetWidth() * 4, destRow );
		destRow += m_texture.GetWidth() * 4;
		row += sourcePitch;
	}
	m_texture.UnmapForReading( renderContext );
	sourcePitch = m_texture.GetWidth() * 4;

	uint32_t destPitch = sourcePitch / 2;

	std::vector<unsigned char>* prevMip = &buffer0;
	std::vector<unsigned char> buffer1( m_texture.GetMipSize( 1 ) );
	std::vector<unsigned char>* nextMip = &buffer1;

	for( unsigned i = 1; i < m_mipLevels; ++i )
	{
		// Construct next mip level data for dirty regions using previous mip level copy in system memory
		// and update rectangles in the texture
		bool updated = false;
		for( auto it = m_dirtyMipRegions.begin(); it != m_dirtyMipRegions.end(); ++it )
		{
			const Tr2Rect source = { it->left >> ( i - 1 ), it->top >> ( i - 1 ), it->right >> ( i - 1 ), it->bottom >> ( i - 1 ) };
			Tr2Rect dest = { it->left >> i, it->top >> i, it->right >> i, it->bottom >> i };
			const int height = dest.bottom - dest.top;
			const int width = dest.right - dest.left;