Method BeginFrame

Plugins/NativeXr/Source/NativeXr.cpp:272–344

    }

    void NativeXr::BeginFrame()
    {
        assert(m_engineImpl != nullptr);
        assert(m_session != nullptr);
        assert(m_frame == nullptr);

        bool shouldEndSession{};
        bool shouldRestartSession{};
        m_frame = m_session->GetNextFrame(shouldEndSession, shouldRestartSession, [this](void* texturePointer){
                auto texPtr = reinterpret_cast<uintptr_t>(texturePointer);
                auto it = m_texturesToFrameBuffers.find(texPtr);
                if (it != m_texturesToFrameBuffers.end())
                {
                    m_texturesToFrameBuffers.erase(it);
                }
            });

        // Ending a session outside of calls to EndSession() is currently not supported.
        assert(!shouldEndSession);
        assert(m_frame != nullptr);

        m_activeFrameBuffers.reserve(m_frame->Views.size());
        for (const auto& view : m_frame->Views)
        {
            auto colorTexPtr = reinterpret_cast<uintptr_t>(view.ColorTexturePointer);

            auto it = m_texturesToFrameBuffers.find(colorTexPtr);
            if (it == m_texturesToFrameBuffers.end() || it->second.get()->Width != view.ColorTextureSize.Width || it->second.get()->Height != view.ColorTextureSize.Height)
            {
                // if a texture width or height is 0, bgfx will assert (can't create 0 sized texture). Asserting here instead of deeper in bgfx rendering
                assert(view.ColorTextureSize.Width); 
                assert(view.ColorTextureSize.Height);
                assert(view.ColorTextureSize.Width == view.DepthTextureSize.Width);
                assert(view.ColorTextureSize.Height == view.DepthTextureSize.Height);

                // Create textures with the desired size. It will be freed and replaced with overrideInternal call
                // This is mandatory as overrideInternal do not update texture size.
                // And size is used for determining viewport when rendering to texture.
                auto colorTextureFormat = XrTextureFormatToBgfxFormat(view.ColorTextureFormat);
                auto colorTex = bgfx::createTexture2D(static_cast<uint16_t>(view.ColorTextureSize.Width), static_cast<uint16_t>(view.ColorTextureSize.Height), false, 1, colorTextureFormat, BGFX_TEXTURE_RT);

                auto depthTextureFormat = XrTextureFormatToBgfxFormat(view.DepthTextureFormat);
                auto depthTex = bgfx::createTexture2D(static_cast<uint16_t>(view.DepthTextureSize.Width), static_cast<uint16_t>(view.DepthTextureSize.Height), false, 1, depthTextureFormat, BGFX_TEXTURE_RT);

                // Force BGFX to create the texture now, which is necessary in order to use overrideInternal.
                bgfx::frame();

                bgfx::overrideInternal(colorTex, colorTexPtr);
                bgfx::overrideInternal(depthTex, reinterpret_cast<uintptr_t>(view.DepthTexturePointer));

                std::array<bgfx::Attachment, 2> attachments{};
                attachments[0].init(colorTex);
                attachments[1].init(depthTex);
                auto frameBuffer = bgfx::createFrameBuffer(static_cast<uint8_t>(attachments.size()), attachments.data(), false);

                auto fbPtr = m_engineImpl->GetFrameBufferManager().CreateNew(
                    frameBuffer,
                    static_cast<uint16_t>(view.ColorTextureSize.Width),