Custom DrawList

[ghost]

Version/Branch of Dear ImGui:

Version: 1.86
Branch: master

Back-end/Renderer/Compiler/OS

Back-ends: DX9 + Win32
Compiler: C++ / Visual Studio
Operating System: Windows 11

My Issue/Question:

How do I render a custom draw list like for example,I can just call ImGui::Render(custom_drawlist);
I was using an old program and that was how it rendered custom drawlist,not sure if it's a specific implementation by the program to render custom draw list.But after I recently update the files to 1.86,the ImGui::Render() function doesn't take any parameters anymore and now I don't know how to render the custom draw list

[ghost]

I tried editing the Render function myself and added the bolded part

for (int n = 0; n != g.Viewports.Size; n++)
    {
        ImGuiViewportP* viewport = g.Viewports[n];
        viewport->DrawDataBuilder.Clear();
        if (viewport->DrawLists[0] != NULL)
            AddDrawListToDrawData(&viewport->DrawDataBuilder.Layers[0], GetBackgroundDrawList(viewport));
        **if (our_list && !our_list->VtxBuffer.empty() && !our_list->CmdBuffer.empty() && !our_list->IdxBuffer.empty())
            AddDrawListToDrawData(&viewport->DrawDataBuilder.Layers[0], our_list);**
    }

But it didn't pass this assert :
IM_ASSERT(draw_list->VtxBuffer.Size == 0 || draw_list->_VtxWritePtr == draw_list->VtxBuffer.Data + draw_list->VtxBuffer.Size);

So I'm guessing I did something wrong and have no idea how any of this works I just want to render menus please help this stuff is giving me headaches

[ghost]

I tried again,the code above worked,just had to comment out the assert (probably not the best thing to do) and changed the code to

if (our_list && !our_list->VtxBuffer.empty())
            AddDrawListToDrawData(&viewport->DrawDataBuilder.Layers[0], our_list);

Please suggest any alternative other than commenting out the assert

[sturnclaw]

You will want to build an ImDrawData object that you can pass into an example render backend or your own custom render backend. This is the way we generate DrawData objects to pass to our custom render backend in Pioneer Space Sim when using the low-level ImDrawList API:

ImDrawData drawData{};
ImDrawList *dl = m_drawList.get();

drawData.Valid = true;
drawData.CmdLists = &dl;
drawData.CmdListsCount = 1;
drawData.TotalVtxCount = dl->VtxBuffer.size();
drawData.TotalIdxCount = dl->IdxBuffer.size();

drawData.DisplayPos = ImVec2(0.0f, 0.0f);
drawData.DisplaySize = ImVec2(Graphics::GetScreenWidth(), Graphics::GetScreenHeight());
drawData.FramebufferScale = ImVec2(1.0f, 1.0f);

Pi::pigui->GetRenderer()->RenderDrawData(&drawData);

I don't make any guarantees that this code works verbatim with a vanilla ImGui render backend, we do things slightly differently to make drawing as efficient as possible, but it should be a good jumping-off point.