// dear imgui: Renderer Backend for SDL_Renderer for SDL2 // (Requires: SDL 2.0.17+) // Note how SDL_Renderer is an _optional_ component of SDL2. // For a multi-platform app consider using e.g. SDL+DirectX on Windows and SDL+OpenGL on Linux/OSX. // If your application will want to render any non trivial amount of graphics other than UI, // please be aware that SDL_Renderer currently offers a limited graphic API to the end-user and // it might be difficult to step out of those boundaries. // Implemented features: // [X] Renderer: User texture binding. Use 'SDL_Texture*' as ImTextureID. Read the FAQ about ImTextureID! // [X] Renderer: Large meshes support (64k+ vertices) with 16-bit indices. // Missing features: // [ ] Renderer: Multi-viewport support (multiple windows). // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this. // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp. // Read online: https://github.com/ocornut/imgui/tree/master/docs // CHANGELOG // 2023-05-30: Renamed imgui_impl_sdlrenderer.h/.cpp to imgui_impl_sdlrenderer2.h/.cpp to accommodate for upcoming SDL3. // 2022-10-11: Using 'nullptr' instead of 'NULL' as per our switch to C++11. // 2021-12-21: Update SDL_RenderGeometryRaw() format to work with SDL 2.0.19. // 2021-12-03: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag. // 2021-10-06: Backup and restore modified ClipRect/Viewport. // 2021-09-21: Initial version. #include "imgui.h" #include "imgui_impl_sdlrenderer2.h" #if defined(_MSC_VER) && _MSC_VER <= 1500 // MSVC 2008 or earlier #include // intptr_t #else #include // intptr_t #endif // Clang warnings with -Weverything #if defined(__clang__) #pragma clang diagnostic push #pragma clang diagnostic ignored "-Wsign-conversion" // warning: implicit conversion changes signedness #endif // SDL #include #if !SDL_VERSION_ATLEAST(2,0,17) #error This backend requires SDL 2.0.17+ because of SDL_RenderGeometry() function #endif // SDL_Renderer data struct ImGui_ImplSDLRenderer2_Data { SDL_Renderer* SDLRenderer; SDL_Texture* FontTexture; ImGui_ImplSDLRenderer2_Data() { memset((void*)this, 0, sizeof(*this)); } }; // Backend data stored in io.BackendRendererUserData to allow support for multiple Dear ImGui contexts // It is STRONGLY preferred that you use docking branch with multi-viewports (== single Dear ImGui context + multiple windows) instead of multiple Dear ImGui contexts. static ImGui_ImplSDLRenderer2_Data* ImGui_ImplSDLRenderer2_GetBackendData() { return ImGui::GetCurrentContext() ? (ImGui_ImplSDLRenderer2_Data*)ImGui::GetIO().BackendRendererUserData : nullptr; } // Functions bool ImGui_ImplSDLRenderer2_Init(SDL_Renderer* renderer) { ImGuiIO& io = ImGui::GetIO(); IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!"); IM_ASSERT(renderer != nullptr && "SDL_Renderer not initialized!"); // Setup backend capabilities flags ImGui_ImplSDLRenderer2_Data* bd = IM_NEW(ImGui_ImplSDLRenderer2_Data)(); io.BackendRendererUserData = (void*)bd; io.BackendRendererName = "imgui_impl_sdlrenderer2"; io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset; // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes. bd->SDLRenderer = renderer; return true; } void ImGui_ImplSDLRenderer2_Shutdown() { ImGui_ImplSDLRenderer2_Data* bd = ImGui_ImplSDLRenderer2_GetBackendData(); IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?"); ImGuiIO& io = ImGui::GetIO(); ImGui_ImplSDLRenderer2_DestroyDeviceObjects(); io.BackendRendererName = nullptr; io.BackendRendererUserData = nullptr; io.BackendFlags &= ~ImGuiBackendFlags_RendererHasVtxOffset; IM_DELETE(bd); } static void ImGui_ImplSDLRenderer2_SetupRenderState() { ImGui_ImplSDLRenderer2_Data* bd = ImGui_ImplSDLRenderer2_GetBackendData(); // 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_RenderSetViewport(bd->SDLRenderer, nullptr); SDL_RenderSetClipRect(bd->SDLRenderer, nullptr); } void ImGui_ImplSDLRenderer2_NewFrame() { ImGui_ImplSDLRenderer2_Data* bd = ImGui_ImplSDLRenderer2_GetBackendData(); IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplSDLRenderer2_Init()?"); if (!bd->FontTexture) ImGui_ImplSDLRenderer2_CreateDeviceObjects(); } void ImGui_ImplSDLRenderer2_RenderDrawData(ImDrawData* draw_data) { ImGui_ImplSDLRenderer2_Data* bd = ImGui_ImplSDLRenderer2_GetBackendData(); // If there's a scale factor set by the user, use that instead // If the user has specified a scale factor to SDL_Renderer already via SDL_RenderSetScale(), SDL will scale whatever we pass // to SDL_RenderGeometryRaw() by that scale factor. In that case we don't want to be also scaling it ourselves here. float rsx = 1.0f; float rsy = 1.0f; SDL_RenderGetScale(bd->SDLRenderer, &rsx, &rsy); ImVec2 render_scale; render_scale.x = (rsx == 1.0f) ? draw_data->FramebufferScale.x : 1.0f; render_scale.y = (rsy == 1.0f) ? draw_data->FramebufferScale.y : 1.0f; // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates) int fb_width = (int)(draw_data->DisplaySize.x * render_scale.x); int fb_height = (int)(draw_data->DisplaySize.y * render_scale.y); if (fb_width == 0 || fb_height == 0) return; // Backup SDL_Renderer state that will be modified to restore it afterwards struct BackupSDLRendererState { SDL_Rect Viewport; bool ClipEnabled; SDL_Rect ClipRect; }; BackupSDLRendererState old = {}; old.ClipEnabled = SDL_RenderIsClipEnabled(bd->SDLRenderer) == SDL_TRUE; SDL_RenderGetViewport(bd->SDLRenderer, &old.Viewport); SDL_RenderGetClipRect(bd->SDLRenderer, &old.ClipRect); // 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; // Render command lists ImGui_ImplSDLRenderer2_SetupRenderState(); for (int n = 0; n < draw_data->CmdListsCount; n++) { const ImDrawList* cmd_list = draw_data->CmdLists[n]; const ImDrawVert* vtx_buffer = cmd_list->VtxBuffer.Data; const ImDrawIdx* idx_buffer = cmd_list->IdxBuffer.Data; for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++) { const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i]; if (pcmd->UserCallback) { // 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_ImplSDLRenderer2_SetupRenderState(); else pcmd->UserCallback(cmd_list, pcmd); } else { // Project scissor/clipping rectangles into framebuffer space ImVec2 clip_min((pcmd->ClipRect.x - clip_off.x) * clip_scale.x, (pcmd->ClipRect.y - clip_off.y) * clip_scale.y); ImVec2 clip_max((pcmd->ClipRect.z - clip_off.x) * clip_scale.x, (pcmd->ClipRect.w - clip_off.y) * clip_scale.y); if (clip_min.x < 0.0f) { clip_min.x = 0.0f; } if (clip_min.y < 0.0f) { clip_min.y = 0.0f; } if (clip_max.x > (float)fb_width) { clip_max.x = (float)fb_width; } if (clip_max.y > (float)fb_height) { clip_max.y = (float)fb_height; } if (clip_max.x <= clip_min.x || clip_max.y <= clip_min.y) continue; SDL_Rect r = { (int)(clip_min.x), (int)(clip_min.y), (int)(clip_max.x - clip_min.x), (int)(clip_max.y - clip_min.y) }; SDL_RenderSetClipRect(bd->SDLRenderer, &r); const float* xy = (const float*)(const void*)((const char*)(vtx_buffer + pcmd->VtxOffset) + IM_OFFSETOF(ImDrawVert, pos)); const float* uv = (const float*)(const void*)((const char*)(vtx_buffer + pcmd->VtxOffset) + IM_OFFSETOF(ImDrawVert, uv)); #if SDL_VERSION_ATLEAST(2,0,19) const SDL_Color* color = (const SDL_Color*)(const void*)((const char*)(vtx_buffer + pcmd->VtxOffset) + IM_OFFSETOF(ImDrawVert, col)); // SDL 2.0.19+ #else const int* color = (const int*)(const void*)((const char*)(vtx_buffer + pcmd->VtxOffset) + IM_OFFSETOF(ImDrawVert, col)); // SDL 2.0.17 and 2.0.18 #endif // Bind texture, Draw SDL_Texture* tex = (SDL_Texture*)pcmd->GetTexID(); SDL_RenderGeometryRaw(bd->SDLRenderer, tex, xy, (int)sizeof(ImDrawVert), color, (int)sizeof(ImDrawVert), uv, (int)sizeof(ImDrawVert), cmd_list->VtxBuffer.Size - pcmd->VtxOffset, idx_buffer + pcmd->IdxOffset, pcmd->ElemCount, sizeof(ImDrawIdx)); } } } // Restore modified SDL_Renderer state SDL_RenderSetViewport(bd->SDLRenderer, &old.Viewport); SDL_RenderSetClipRect(bd->SDLRenderer, old.ClipEnabled ? &old.ClipRect : nullptr); } // Called by Init/NewFrame/Shutdown bool ImGui_ImplSDLRenderer2_CreateFontsTexture() { ImGuiIO& io = ImGui::GetIO(); ImGui_ImplSDLRenderer2_Data* bd = ImGui_ImplSDLRenderer2_GetBackendData(); // Build texture atlas unsigned char* pixels; int width, height; io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height); // Load as RGBA 32-bit (75% of the memory is wasted, but default font is so small) because it is more likely to be compatible with user's existing shaders. If your ImTextureId represent a higher-level concept than just a GL texture id, consider calling GetTexDataAsAlpha8() instead to save on GPU memory. // Upload texture to graphics system // (Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling) bd->FontTexture = SDL_CreateTexture(bd->SDLRenderer, SDL_PIXELFORMAT_ABGR8888, SDL_TEXTUREACCESS_STATIC, width, height); if (bd->FontTexture == nullptr) { SDL_Log("error creating texture"); return false; } SDL_UpdateTexture(bd->FontTexture, nullptr, pixels, 4 * width); SDL_SetTextureBlendMode(bd->FontTexture, SDL_BLENDMODE_BLEND); SDL_SetTextureScaleMode(bd->FontTexture, SDL_ScaleModeLinear); // Store our identifier io.Fonts->SetTexID((ImTextureID)(intptr_t)bd->FontTexture); return true; } void ImGui_ImplSDLRenderer2_DestroyFontsTexture() { ImGuiIO& io = ImGui::GetIO(); ImGui_ImplSDLRenderer2_Data* bd = ImGui_ImplSDLRenderer2_GetBackendData(); if (bd->FontTexture) { io.Fonts->SetTexID(0); SDL_DestroyTexture(bd->FontTexture); bd->FontTexture = nullptr; } } bool ImGui_ImplSDLRenderer2_CreateDeviceObjects() { return ImGui_ImplSDLRenderer2_CreateFontsTexture(); } void ImGui_ImplSDLRenderer2_DestroyDeviceObjects() { ImGui_ImplSDLRenderer2_DestroyFontsTexture(); } #if defined(__clang__) #pragma clang diagnostic pop #endif