From f296bec7ca965d716cb747e4a75f9b3e8f4b0437 Mon Sep 17 00:00:00 2001 From: Clownacy Date: Sun, 13 Sep 2026 13:15:52 +0100 Subject: [PATCH] SDL3: Allow overriding scale mode. SDL3 features a unique scale mode that is neither nearest nor linear, that being `SDL_SCALEMODE_PIXELART`, and I want to use it in my emulator. Dear ImGui prevents this by forcefully overriding the texture's defined scale mode, so this commit allows Dear ImGui to be overridden in turn. Previously the scale mode was hidden within the internal state, but now it is exposed in the public render state struct. ocornut#9378 mentions opening an issue if anyone ever wants access to this internal state, but I think a PR will do better. --- backends/imgui_impl_sdlrenderer3.cpp | 28 +++++++++++++++------------- backends/imgui_impl_sdlrenderer3.h | 3 ++- 2 files changed, 17 insertions(+), 14 deletions(-) diff --git a/backends/imgui_impl_sdlrenderer3.cpp b/backends/imgui_impl_sdlrenderer3.cpp index cb975393e..6505b9075 100644 --- a/backends/imgui_impl_sdlrenderer3.cpp +++ b/backends/imgui_impl_sdlrenderer3.cpp @@ -62,9 +62,6 @@ struct ImGui_ImplSDLRenderer3_Data SDL_Renderer* Renderer; // Main viewport's renderer ImVector ColorBuffer; - // Render State - SDL_ScaleMode CurrentScaleMode; - ImGui_ImplSDLRenderer3_Data() { memset((void*)this, 0, sizeof(*this)); } }; @@ -75,17 +72,22 @@ static ImGui_ImplSDLRenderer3_Data* ImGui_ImplSDLRenderer3_GetBackendData() return ImGui::GetCurrentContext() ? (ImGui_ImplSDLRenderer3_Data*)ImGui::GetIO().BackendRendererUserData : nullptr; } +static ImGui_ImplSDLRenderer3_RenderState* ImGui_ImplSDLRenderer3_GetRenderState() +{ + return (ImGui_ImplSDLRenderer3_RenderState*)ImGui::GetPlatformIO().Renderer_RenderState; +} + // Functions static void ImGui_ImplSDLRenderer3_SetupRenderState(SDL_Renderer* renderer) { - ImGui_ImplSDLRenderer3_Data* bd = ImGui_ImplSDLRenderer3_GetBackendData(); + ImGui_ImplSDLRenderer3_RenderState* render_state = ImGui_ImplSDLRenderer3_GetRenderState(); // Clear out any viewports and cliprect set by the user // FIXME: Technically speaking there are lots of other things we could backup/setup/restore during our render process. SDL_SetRenderViewport(renderer, nullptr); SDL_SetRenderClipRect(renderer, nullptr); - bd->CurrentScaleMode = SDL_SCALEMODE_LINEAR; + render_state->CurrentScaleMode = SDL_SCALEMODE_LINEAR; } void ImGui_ImplSDLRenderer3_NewFrame() @@ -115,8 +117,8 @@ static int SDL_RenderGeometryRaw8BitColor(SDL_Renderer* renderer, ImVectorCurrentScaleMode = SDL_SCALEMODE_LINEAR; } -static void ImGui_ImplSDLRenderer3_DrawCallback_SetSamplerNearest(const ImDrawList*, const ImDrawCmd*) { ImGui_ImplSDLRenderer3_Data* bd = ImGui_ImplSDLRenderer3_GetBackendData(); bd->CurrentScaleMode = SDL_SCALEMODE_NEAREST; } +static void ImGui_ImplSDLRenderer3_DrawCallback_SetSamplerLinear(const ImDrawList*, const ImDrawCmd*) { ImGui_ImplSDLRenderer3_RenderState* render_state = ImGui_ImplSDLRenderer3_GetRenderState(); render_state->CurrentScaleMode = SDL_SCALEMODE_LINEAR; } +static void ImGui_ImplSDLRenderer3_DrawCallback_SetSamplerNearest(const ImDrawList*, const ImDrawCmd*) { ImGui_ImplSDLRenderer3_RenderState* render_state = ImGui_ImplSDLRenderer3_GetRenderState(); render_state->CurrentScaleMode = SDL_SCALEMODE_NEAREST; } void ImGui_ImplSDLRenderer3_RenderDrawData(ImDrawData* draw_data, SDL_Renderer* renderer) { @@ -159,19 +161,19 @@ void ImGui_ImplSDLRenderer3_RenderDrawData(ImDrawData* draw_data, SDL_Renderer* SDL_GetRenderViewport(renderer, &old.Viewport); SDL_GetRenderClipRect(renderer, &old.ClipRect); - // Setup desired state - ImGui_ImplSDLRenderer3_SetupRenderState(renderer); - // Setup render state structure (for callbacks and custom texture bindings) ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO(); ImGui_ImplSDLRenderer3_RenderState render_state; render_state.Renderer = renderer; platform_io.Renderer_RenderState = &render_state; + // Setup desired state + ImGui_ImplSDLRenderer3_SetupRenderState(renderer); + // Will project scissor/clipping rectangles into framebuffer space ImVec2 clip_off = draw_data->DisplayPos; // (0,0) unless using multi-viewports ImVec2 clip_scale = render_scale; - SDL_ScaleMode last_scale_mode = bd->CurrentScaleMode; + SDL_ScaleMode last_scale_mode = render_state.CurrentScaleMode; // Render command lists for (const ImDrawList* draw_list : draw_data->CmdLists) @@ -209,12 +211,12 @@ void ImGui_ImplSDLRenderer3_RenderDrawData(ImDrawData* draw_data, SDL_Renderer* const float* uv = (const float*)(const void*)((const char*)(vtx_buffer + pcmd->VtxOffset) + offsetof(ImDrawVert, uv)); const SDL_Color* color = (const SDL_Color*)(const void*)((const char*)(vtx_buffer + pcmd->VtxOffset) + offsetof(ImDrawVert, col)); // SDL 2.0.19+ - if (last_scale_mode != bd->CurrentScaleMode) + if (last_scale_mode != render_state.CurrentScaleMode) SDL_FlushRenderer(renderer); // Bind texture, Draw SDL_Texture* tex = (SDL_Texture*)pcmd->GetTexID(); - SDL_SetTextureScaleMode(tex, bd->CurrentScaleMode); + SDL_SetTextureScaleMode(tex, render_state.CurrentScaleMode); SDL_RenderGeometryRaw8BitColor(renderer, bd->ColorBuffer, tex, xy, (int)sizeof(ImDrawVert), color, (int)sizeof(ImDrawVert), diff --git a/backends/imgui_impl_sdlrenderer3.h b/backends/imgui_impl_sdlrenderer3.h index c01a16d48..6fbf9d89e 100644 --- a/backends/imgui_impl_sdlrenderer3.h +++ b/backends/imgui_impl_sdlrenderer3.h @@ -27,7 +27,7 @@ #include "imgui.h" // IMGUI_IMPL_API #ifndef IMGUI_DISABLE -struct SDL_Renderer; +#include // Follow "Getting Started" link and check examples/ folder to learn about using backends! IMGUI_IMPL_API bool ImGui_ImplSDLRenderer3_Init(SDL_Renderer* renderer); @@ -48,6 +48,7 @@ IMGUI_IMPL_API void ImGui_ImplSDLRenderer3_UpdateTexture(ImTextureData* tex) struct ImGui_ImplSDLRenderer3_RenderState { SDL_Renderer* Renderer; + SDL_ScaleMode CurrentScaleMode; }; #endif // #ifndef IMGUI_DISABLE