flag use-ImDrawIdx32

dear-implot.cabal

@@ -18,6 +18,17 @@ flag use-wchar32
   manual:
     True
 
+flag use-ImDrawIdx32
+  description:
+    Use 32-bit vertex indices (default is 16-bit) is one way to allow large meshes with more than 64K vertices.
+    Your renderer backend will need to support it (most example renderer backends support both 16/32-bit indices).
+    Another way to allow large meshes while keeping 16-bit indices is to handle ImDrawCmd::VtxOffset in your renderer.
+    Read about ImGuiBackendFlags_RendererHasVtxOffset for details.
+  default:
+    True
+  manual:
+    True
+
 library
   exposed-modules:
     DearImGui.Raw.Plot
@@ -61,9 +72,15 @@ library
   include-dirs:
     implot
     dear-imgui.hs/imgui
+
   if flag(use-wchar32)
     cxx-options: -DIMGUI_USE_WCHAR32
     cpp-options: -DIMGUI_USE_WCHAR32
+
+  if flag(use-ImDrawIdx32)
+    cxx-options: "-DImDrawIdx=unsigned int"
+    cpp-options: "-DImDrawIdx=unsigned int"
+
   build-depends: base
                , StateVar
                , containers