250 lines
10 KiB
C++
250 lines
10 KiB
C++
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// dear imgui: Renderer Backend for SDL_Renderer
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// (Requires: SDL 2.0.17+)
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// Important to understand: SDL_Renderer is an _optional_ component of SDL.
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// For a multi-platform app consider using e.g. SDL+DirectX on Windows and SDL+OpenGL on Linux/OSX.
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// If your application will want to render any non trivial amount of graphics other than UI,
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// please be aware that SDL_Renderer offers a limited graphic API to the end-user and it might
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// be difficult to step out of those boundaries.
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// However, we understand it is a convenient choice to get an app started easily.
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// Implemented features:
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// [X] Renderer: User texture binding. Use 'SDL_Texture*' as ImTextureID. Read the FAQ about ImTextureID!
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// [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
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// Missing features:
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// [ ] Renderer: Multi-viewport support (multiple windows).
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// You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
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// If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
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// Read online: https://github.com/ocornut/imgui/tree/master/docs
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// CHANGELOG
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// 2021-12-21: Update SDL_RenderGeometryRaw() format to work with SDL 2.0.19.
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// 2021-12-03: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
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// 2021-10-06: Backup and restore modified ClipRect/Viewport.
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// 2021-09-21: Initial version.
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#include "imgui.h"
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#include "imgui_impl_sdlrenderer.h"
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#if defined(_MSC_VER) && _MSC_VER <= 1500 // MSVC 2008 or earlier
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#include <stddef.h> // intptr_t
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#else
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#include <stdint.h> // intptr_t
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#endif
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// SDL
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#include <SDL.h>
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#if !SDL_VERSION_ATLEAST(2,0,17)
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#error This backend requires SDL 2.0.17+ because of SDL_RenderGeometry() function
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#endif
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// SDL_Renderer data
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struct ImGui_ImplSDLRenderer_Data
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{
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SDL_Renderer* SDLRenderer;
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SDL_Texture* FontTexture;
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ImGui_ImplSDLRenderer_Data() { memset(this, 0, sizeof(*this)); }
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};
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// Backend data stored in io.BackendRendererUserData to allow support for multiple Dear ImGui contexts
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// It is STRONGLY preferred that you use docking branch with multi-viewports (== single Dear ImGui context + multiple windows) instead of multiple Dear ImGui contexts.
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static ImGui_ImplSDLRenderer_Data* ImGui_ImplSDLRenderer_GetBackendData()
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{
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return ImGui::GetCurrentContext() ? (ImGui_ImplSDLRenderer_Data*)ImGui::GetIO().BackendRendererUserData : NULL;
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}
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// Functions
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bool ImGui_ImplSDLRenderer_Init(SDL_Renderer* renderer)
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{
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ImGuiIO& io = ImGui::GetIO();
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IM_ASSERT(io.BackendRendererUserData == NULL && "Already initialized a renderer backend!");
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IM_ASSERT(renderer != NULL && "SDL_Renderer not initialized!");
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// Setup backend capabilities flags
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ImGui_ImplSDLRenderer_Data* bd = IM_NEW(ImGui_ImplSDLRenderer_Data)();
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io.BackendRendererUserData = (void*)bd;
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io.BackendRendererName = "imgui_impl_sdlrenderer";
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io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset; // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
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bd->SDLRenderer = renderer;
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return true;
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}
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void ImGui_ImplSDLRenderer_Shutdown()
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{
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ImGui_ImplSDLRenderer_Data* bd = ImGui_ImplSDLRenderer_GetBackendData();
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IM_ASSERT(bd != NULL && "No renderer backend to shutdown, or already shutdown?");
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ImGuiIO& io = ImGui::GetIO();
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ImGui_ImplSDLRenderer_DestroyDeviceObjects();
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io.BackendRendererName = NULL;
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io.BackendRendererUserData = NULL;
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IM_DELETE(bd);
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}
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static void ImGui_ImplSDLRenderer_SetupRenderState()
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{
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ImGui_ImplSDLRenderer_Data* bd = ImGui_ImplSDLRenderer_GetBackendData();
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// Clear out any viewports and cliprect set by the user
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// FIXME: Technically speaking there are lots of other things we could backup/setup/restore during our render process.
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SDL_RenderSetViewport(bd->SDLRenderer, NULL);
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SDL_RenderSetClipRect(bd->SDLRenderer, NULL);
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}
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void ImGui_ImplSDLRenderer_NewFrame()
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{
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ImGui_ImplSDLRenderer_Data* bd = ImGui_ImplSDLRenderer_GetBackendData();
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IM_ASSERT(bd != NULL && "Did you call ImGui_ImplSDLRenderer_Init()?");
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if (!bd->FontTexture)
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ImGui_ImplSDLRenderer_CreateDeviceObjects();
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}
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void ImGui_ImplSDLRenderer_RenderDrawData(ImDrawData* draw_data)
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{
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ImGui_ImplSDLRenderer_Data* bd = ImGui_ImplSDLRenderer_GetBackendData();
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// If there's a scale factor set by the user, use that instead
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// If the user has specified a scale factor to SDL_Renderer already via SDL_RenderSetScale(), SDL will scale whatever we pass
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// to SDL_RenderGeometryRaw() by that scale factor. In that case we don't want to be also scaling it ourselves here.
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float rsx = 1.0f;
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float rsy = 1.0f;
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SDL_RenderGetScale(bd->SDLRenderer, &rsx, &rsy);
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ImVec2 render_scale;
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render_scale.x = (rsx == 1.0f) ? draw_data->FramebufferScale.x : 1.0f;
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render_scale.y = (rsy == 1.0f) ? draw_data->FramebufferScale.y : 1.0f;
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// Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
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int fb_width = (int)(draw_data->DisplaySize.x * render_scale.x);
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int fb_height = (int)(draw_data->DisplaySize.y * render_scale.y);
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if (fb_width == 0 || fb_height == 0)
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return;
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// Backup SDL_Renderer state that will be modified to restore it afterwards
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struct BackupSDLRendererState
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{
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SDL_Rect Viewport;
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bool ClipEnabled;
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SDL_Rect ClipRect;
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};
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BackupSDLRendererState old = {};
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old.ClipEnabled = SDL_RenderIsClipEnabled(bd->SDLRenderer) == SDL_TRUE;
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SDL_RenderGetViewport(bd->SDLRenderer, &old.Viewport);
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SDL_RenderGetClipRect(bd->SDLRenderer, &old.ClipRect);
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// Will project scissor/clipping rectangles into framebuffer space
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ImVec2 clip_off = draw_data->DisplayPos; // (0,0) unless using multi-viewports
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ImVec2 clip_scale = render_scale;
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// Render command lists
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ImGui_ImplSDLRenderer_SetupRenderState();
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for (int n = 0; n < draw_data->CmdListsCount; n++)
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{
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const ImDrawList* cmd_list = draw_data->CmdLists[n];
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const ImDrawVert* vtx_buffer = cmd_list->VtxBuffer.Data;
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const ImDrawIdx* idx_buffer = cmd_list->IdxBuffer.Data;
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for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
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{
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const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
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if (pcmd->UserCallback)
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{
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// User callback, registered via ImDrawList::AddCallback()
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// (ImDrawCallback_ResetRenderState is a special callback value used by the user to request the renderer to reset render state.)
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if (pcmd->UserCallback == ImDrawCallback_ResetRenderState)
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ImGui_ImplSDLRenderer_SetupRenderState();
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else
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pcmd->UserCallback(cmd_list, pcmd);
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}
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else
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{
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// Project scissor/clipping rectangles into framebuffer space
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ImVec2 clip_min((pcmd->ClipRect.x - clip_off.x) * clip_scale.x, (pcmd->ClipRect.y - clip_off.y) * clip_scale.y);
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ImVec2 clip_max((pcmd->ClipRect.z - clip_off.x) * clip_scale.x, (pcmd->ClipRect.w - clip_off.y) * clip_scale.y);
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if (clip_min.x < 0.0f) { clip_min.x = 0.0f; }
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if (clip_min.y < 0.0f) { clip_min.y = 0.0f; }
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if (clip_max.x > fb_width) { clip_max.x = (float)fb_width; }
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if (clip_max.y > fb_height) { clip_max.y = (float)fb_height; }
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if (clip_max.x <= clip_min.x || clip_max.y <= clip_min.y)
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continue;
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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) };
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SDL_RenderSetClipRect(bd->SDLRenderer, &r);
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const float* xy = (const float*)((const char*)(vtx_buffer + pcmd->VtxOffset) + IM_OFFSETOF(ImDrawVert, pos));
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const float* uv = (const float*)((const char*)(vtx_buffer + pcmd->VtxOffset) + IM_OFFSETOF(ImDrawVert, uv));
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#if SDL_VERSION_ATLEAST(2,0,19)
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const SDL_Color* color = (const SDL_Color*)((const char*)(vtx_buffer + pcmd->VtxOffset) + IM_OFFSETOF(ImDrawVert, col)); // SDL 2.0.19+
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#else
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const int* color = (const int*)((const char*)(vtx_buffer + pcmd->VtxOffset) + IM_OFFSETOF(ImDrawVert, col)); // SDL 2.0.17 and 2.0.18
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#endif
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// Bind texture, Draw
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SDL_Texture* tex = (SDL_Texture*)pcmd->GetTexID();
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SDL_RenderGeometryRaw(bd->SDLRenderer, tex,
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xy, (int)sizeof(ImDrawVert),
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color, (int)sizeof(ImDrawVert),
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uv, (int)sizeof(ImDrawVert),
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cmd_list->VtxBuffer.Size - pcmd->VtxOffset,
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idx_buffer + pcmd->IdxOffset, pcmd->ElemCount, sizeof(ImDrawIdx));
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}
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}
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}
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// Restore modified SDL_Renderer state
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SDL_RenderSetViewport(bd->SDLRenderer, &old.Viewport);
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SDL_RenderSetClipRect(bd->SDLRenderer, old.ClipEnabled ? &old.ClipRect : NULL);
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}
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// Called by Init/NewFrame/Shutdown
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bool ImGui_ImplSDLRenderer_CreateFontsTexture()
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{
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ImGuiIO& io = ImGui::GetIO();
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ImGui_ImplSDLRenderer_Data* bd = ImGui_ImplSDLRenderer_GetBackendData();
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// Build texture atlas
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unsigned char* pixels;
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int width, height;
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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.
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// Upload texture to graphics system
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bd->FontTexture = SDL_CreateTexture(bd->SDLRenderer, SDL_PIXELFORMAT_ABGR8888, SDL_TEXTUREACCESS_STATIC, width, height);
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if (bd->FontTexture == NULL)
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{
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SDL_Log("error creating texture");
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return false;
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}
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SDL_UpdateTexture(bd->FontTexture, NULL, pixels, 4 * width);
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SDL_SetTextureBlendMode(bd->FontTexture, SDL_BLENDMODE_BLEND);
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// Store our identifier
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io.Fonts->SetTexID((ImTextureID)(intptr_t)bd->FontTexture);
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return true;
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}
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void ImGui_ImplSDLRenderer_DestroyFontsTexture()
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{
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ImGuiIO& io = ImGui::GetIO();
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ImGui_ImplSDLRenderer_Data* bd = ImGui_ImplSDLRenderer_GetBackendData();
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if (bd->FontTexture)
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{
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io.Fonts->SetTexID(0);
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SDL_DestroyTexture(bd->FontTexture);
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bd->FontTexture = NULL;
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}
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}
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bool ImGui_ImplSDLRenderer_CreateDeviceObjects()
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{
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return ImGui_ImplSDLRenderer_CreateFontsTexture();
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}
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void ImGui_ImplSDLRenderer_DestroyDeviceObjects()
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{
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ImGui_ImplSDLRenderer_DestroyFontsTexture();
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}
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