Backends: SDLGPU3: added support for ImDrawCallback_ResetRenderState. (#8599)

backends/imgui_impl_sdlgpu3.cpp

@@ -21,6 +21,7 @@
 //   Calling the function is MANDATORY, otherwise the ImGui will not upload neither the vertex nor the index buffer for the GPU. See imgui_impl_sdlgpu3.cpp for more info.
 
 // CHANGELOG
+//  2025-04-28: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
 //  2025-03-30: Made ImGui_ImplSDLGPU3_PrepareDrawData() reuse GPU Transfer Buffers which were unusually slow to recreate every frame. Much faster now.
 //  2025-03-21: Fixed typo in function name Imgui_ImplSDLGPU3_PrepareDrawData() -> ImGui_ImplSDLGPU3_PrepareDrawData().
 //  2025-01-16: Renamed ImGui_ImplSDLGPU3_InitInfo::GpuDevice to Device.
@@ -232,7 +233,12 @@ void ImGui_ImplSDLGPU3_RenderDrawData(ImDrawData* draw_data, SDL_GPUCommandBuffe
             const ImDrawCmd* pcmd = &draw_list->CmdBuffer[cmd_i];
             if (pcmd->UserCallback != nullptr)
             {
-                pcmd->UserCallback(draw_list, pcmd);
+                // User callback, registered via ImDrawList::AddCallback()
+                // (ImDrawCallback_ResetRenderState is a special callback value used by the user to request the renderer to reset render state.)
+                if (pcmd->UserCallback == ImDrawCallback_ResetRenderState)
+                    ImGui_ImplSDLGPU3_SetupRenderState(draw_data, pipeline, command_buffer, render_pass, fd, fb_width, fb_height);
+                else
+                    pcmd->UserCallback(draw_list, pcmd);
             }
             else
             {

docs/CHANGELOG.txt

@@ -111,6 +111,7 @@ Other changes:
   way to call SDL_StartTextInput(), without IME being necessarily visible. (#8584)
 - Backends: SDLGPU3: Made ImGui_ImplSDLGPU3_PrepareDrawData() reuse GPU Transfer Buffers which
   were unusually slow to recreate every frame. Much faster now. (#8534) [@ocornut, @TheMode]
+- Backends: SDLGPU3: added support for ImDrawCallback_ResetRenderState. (#8599)
 - Backends: Vulkan: Deep-copy ImGui_ImplVulkan_InitInfo::PipelineRenderingCreateInfo's
   pColorAttachmentFormats buffer when set, in order to reduce common user-error of
   specifying a pointer to data that gets out of scope. (#8282)