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ShaderPlayground / deps / imgui / imgui / backends / imgui_impl_sdlrenderer2.cpp
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1// dear imgui: Renderer Backend for SDL_Renderer for SDL2
2// (Requires: SDL 2.0.17+)
3
4// Note that SDL_Renderer is an _optional_ component of SDL2, which IMHO is now largely obsolete.
5// For a multi-platform app consider using other technologies:
6// - SDL3+SDL_GPU: SDL_GPU is SDL3 new graphics abstraction API. You will need to update to SDL3.
7// - SDL2+DirectX, SDL2+OpenGL, SDL2+Vulkan: combine SDL with dedicated renderers.
8// If your application wants to render any non trivial amount of graphics other than UI,
9// please be aware that SDL_Renderer currently offers a limited graphic API to the end-user
10// and it might be difficult to step out of those boundaries.
11
12// Implemented features:
13// [X] Renderer: User texture binding. Use 'SDL_Texture*' as texture identifier. Read the FAQ about ImTextureID/ImTextureRef!
14// [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
15// [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
16// [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
17// Missing features or Issues:
18// [ ] Renderer: Multi-viewport support (multiple windows).
19// [ ] Renderer: Missing support for DrawCallback_SetSamplerLinear, DrawCallback_SetSamplerNearest callbacks: SDLRenderer2 does not support changing SDL_SCALE_MODE while rendering.
20
21// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
22// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
23// Learn about Dear ImGui:
24// - FAQ https://dearimgui.com/faq
25// - Getting Started https://dearimgui.com/getting-started
26// - Documentation https://dearimgui.com/docs (same as your local docs/ folder).
27// - Introduction, links and more at the top of imgui.cpp
28
29// CHANGELOG
30// (minor and older changes stripped away, please see git history for details)
31// 2026-04-23: Added support for standard draw callbacks (in platform_io): DrawCallback_ResetRenderState (others cannot be supported). (#9378)
32// 2026-03-12: Fixed invalid assert in ImGui_ImplSDLRenderer2_UpdateTexture() if ImTextureID_Invalid is defined to be != 0, which became the default since 2026-03-12. (#9295)
33// 2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
34// 2025-06-11: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. Removed ImGui_ImplSDLRenderer2_CreateFontsTexture() and ImGui_ImplSDLRenderer2_DestroyFontsTexture().
35// 2025-01-18: Use endian-dependent RGBA32 texture format, to match SDL_Color.
36// 2024-10-09: Expose selected render state in ImGui_ImplSDLRenderer2_RenderState, which you can access in 'void* platform_io.Renderer_RenderState' during draw callbacks.
37// 2024-05-14: *BREAKING CHANGE* ImGui_ImplSDLRenderer3_RenderDrawData() requires SDL_Renderer* passed as parameter.
38// 2023-05-30: Renamed imgui_impl_sdlrenderer.h/.cpp to imgui_impl_sdlrenderer2.h/.cpp to accommodate for upcoming SDL3.
39// 2022-10-11: Using 'nullptr' instead of 'NULL' as per our switch to C++11.
40// 2021-12-21: Update SDL_RenderGeometryRaw() format to work with SDL 2.0.19.
41// 2021-12-03: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
42// 2021-10-06: Backup and restore modified ClipRect/Viewport.
43// 2021-09-21: Initial version.
44
45#include "imgui.h"
46#ifndef IMGUI_DISABLE
47#include "imgui_impl_sdlrenderer2.h"
48#include <stdint.h> // intptr_t
49
50// Clang warnings with -Weverything
51#if defined(__clang__)
52#pragma clang diagnostic push
53#pragma clang diagnostic ignored "-Wsign-conversion" // warning: implicit conversion changes signedness
54#elif defined(__GNUC__)
55#pragma GCC diagnostic ignored "-Wfloat-equal" // warning: comparing floating-point with '==' or '!=' is unsafe
56#endif
57
58// SDL
59#include <SDL.h>
60#if !SDL_VERSION_ATLEAST(2,0,17)
61#error This backend requires SDL 2.0.17+ because of SDL_RenderGeometry() function
62#endif
63
64// SDL_Renderer data
65struct ImGui_ImplSDLRenderer2_Data
66{
67 SDL_Renderer* Renderer; // Main viewport's renderer
68
69 ImGui_ImplSDLRenderer2_Data() { memset((void*)this, 0, sizeof(*this)); }
70};
71
72// Backend data stored in io.BackendRendererUserData to allow support for multiple Dear ImGui contexts
73// It is STRONGLY preferred that you use docking branch with multi-viewports (== single Dear ImGui context + multiple windows) instead of multiple Dear ImGui contexts.
74static ImGui_ImplSDLRenderer2_Data* ImGui_ImplSDLRenderer2_GetBackendData()
75{
76 return ImGui::GetCurrentContext() ? (ImGui_ImplSDLRenderer2_Data*)ImGui::GetIO().BackendRendererUserData : nullptr;
77}
78
79// Functions
80static void ImGui_ImplSDLRenderer2_SetupRenderState(SDL_Renderer* renderer)
81{
82 // Clear out any viewports and cliprect set by the user
83 // FIXME: Technically speaking there are lots of other things we could backup/setup/restore during our render process.
84 SDL_RenderSetViewport(renderer, nullptr);
85 SDL_RenderSetClipRect(renderer, nullptr);
86}
87
88void ImGui_ImplSDLRenderer2_NewFrame()
89{
90 ImGui_ImplSDLRenderer2_Data* bd = ImGui_ImplSDLRenderer2_GetBackendData();
91 IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplSDLRenderer2_Init()?");
92 IM_UNUSED(bd);
93}
94
95// Draw callbacks
96static void ImGui_ImplSDLRenderer2_DrawCallback_ResetRenderState(const ImDrawList*, const ImDrawCmd*) {} // Intentionally empty. Used as an identifier for rendering loop to call its code. Simpler to implement this way.
97
98void ImGui_ImplSDLRenderer2_RenderDrawData(ImDrawData* draw_data, SDL_Renderer* renderer)
99{
100 // If there's a scale factor set by the user, use that instead
101 // If the user has specified a scale factor to SDL_Renderer already via SDL_RenderSetScale(), SDL will scale whatever we pass
102 // to SDL_RenderGeometryRaw() by that scale factor. In that case we don't want to be also scaling it ourselves here.
103 float rsx = 1.0f;
104 float rsy = 1.0f;
105 SDL_RenderGetScale(renderer, &rsx, &rsy);
106 ImVec2 render_scale;
107 render_scale.x = (rsx == 1.0f) ? draw_data->FramebufferScale.x : 1.0f;
108 render_scale.y = (rsy == 1.0f) ? draw_data->FramebufferScale.y : 1.0f;
109
110 // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
111 int fb_width = (int)(draw_data->DisplaySize.x * render_scale.x);
112 int fb_height = (int)(draw_data->DisplaySize.y * render_scale.y);
113 if (fb_width == 0 || fb_height == 0)
114 return;
115
116 // Catch up with texture updates. Most of the times, the list will have 1 element with an OK status, aka nothing to do.
117 // (This almost always points to ImGui::GetPlatformIO().Textures[] but is part of ImDrawData to allow overriding or disabling texture updates).
118 if (draw_data->Textures != nullptr)
119 for (ImTextureData* tex : *draw_data->Textures)
120 if (tex->Status != ImTextureStatus_OK)
121 ImGui_ImplSDLRenderer2_UpdateTexture(tex);
122
123 // Backup SDL_Renderer state that will be modified to restore it afterwards
124 struct BackupSDLRendererState
125 {
126 SDL_Rect Viewport;
127 bool ClipEnabled;
128 SDL_Rect ClipRect;
129 };
130 BackupSDLRendererState old = {};
131 old.ClipEnabled = SDL_RenderIsClipEnabled(renderer) == SDL_TRUE;
132 SDL_RenderGetViewport(renderer, &old.Viewport);
133 SDL_RenderGetClipRect(renderer, &old.ClipRect);
134
135 // Setup desired state
136 ImGui_ImplSDLRenderer2_SetupRenderState(renderer);
137
138 // Setup render state structure (for callbacks and custom texture bindings)
139 ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
140 ImGui_ImplSDLRenderer2_RenderState render_state;
141 render_state.Renderer = renderer;
142 platform_io.Renderer_RenderState = &render_state;
143
144 // Will project scissor/clipping rectangles into framebuffer space
145 ImVec2 clip_off = draw_data->DisplayPos; // (0,0) unless using multi-viewports
146 ImVec2 clip_scale = render_scale;
147
148 // Render command lists
149 for (const ImDrawList* draw_list : draw_data->CmdLists)
150 {
151 const ImDrawVert* vtx_buffer = draw_list->VtxBuffer.Data;
152 const ImDrawIdx* idx_buffer = draw_list->IdxBuffer.Data;
153
154 for (int cmd_i = 0; cmd_i < draw_list->CmdBuffer.Size; cmd_i++)
155 {
156 const ImDrawCmd* pcmd = &draw_list->CmdBuffer[cmd_i];
157 if (pcmd->UserCallback)
158 {
159 // User callback, registered via ImDrawList::AddCallback()
160 if (pcmd->UserCallback == ImGui_ImplSDLRenderer2_DrawCallback_ResetRenderState)
161 ImGui_ImplSDLRenderer2_SetupRenderState(renderer);
162 else
163 pcmd->UserCallback(draw_list, pcmd);
164 }
165 else
166 {
167 // Project scissor/clipping rectangles into framebuffer space
168 ImVec2 clip_min((pcmd->ClipRect.x - clip_off.x) * clip_scale.x, (pcmd->ClipRect.y - clip_off.y) * clip_scale.y);
169 ImVec2 clip_max((pcmd->ClipRect.z - clip_off.x) * clip_scale.x, (pcmd->ClipRect.w - clip_off.y) * clip_scale.y);
170 if (clip_min.x < 0.0f) { clip_min.x = 0.0f; }
171 if (clip_min.y < 0.0f) { clip_min.y = 0.0f; }
172 if (clip_max.x > (float)fb_width) { clip_max.x = (float)fb_width; }
173 if (clip_max.y > (float)fb_height) { clip_max.y = (float)fb_height; }
174 if (clip_max.x <= clip_min.x || clip_max.y <= clip_min.y)
175 continue;
176
177 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) };
178 SDL_RenderSetClipRect(renderer, &r);
179
180 const float* xy = (const float*)(const void*)((const char*)(vtx_buffer + pcmd->VtxOffset) + offsetof(ImDrawVert, pos));
181 const float* uv = (const float*)(const void*)((const char*)(vtx_buffer + pcmd->VtxOffset) + offsetof(ImDrawVert, uv));
182#if SDL_VERSION_ATLEAST(2,0,19)
183 const SDL_Color* color = (const SDL_Color*)(const void*)((const char*)(vtx_buffer + pcmd->VtxOffset) + offsetof(ImDrawVert, col)); // SDL 2.0.19+
184#else
185 const int* color = (const int*)(const void*)((const char*)(vtx_buffer + pcmd->VtxOffset) + offsetof(ImDrawVert, col)); // SDL 2.0.17 and 2.0.18
186#endif
187
188 // Bind texture, Draw
189 SDL_Texture* tex = (SDL_Texture*)pcmd->GetTexID();
190 SDL_RenderGeometryRaw(renderer, tex,
191 xy, (int)sizeof(ImDrawVert),
192 color, (int)sizeof(ImDrawVert),
193 uv, (int)sizeof(ImDrawVert),
194 draw_list->VtxBuffer.Size - pcmd->VtxOffset,
195 idx_buffer + pcmd->IdxOffset, pcmd->ElemCount, sizeof(ImDrawIdx));
196 }
197 }
198 }
199 platform_io.Renderer_RenderState = nullptr;
200
201 // Restore modified SDL_Renderer state
202 SDL_RenderSetViewport(renderer, &old.Viewport);
203 SDL_RenderSetClipRect(renderer, old.ClipEnabled ? &old.ClipRect : nullptr);
204}
205
206void ImGui_ImplSDLRenderer2_UpdateTexture(ImTextureData* tex)
207{
208 ImGui_ImplSDLRenderer2_Data* bd = ImGui_ImplSDLRenderer2_GetBackendData();
209
210 if (tex->Status == ImTextureStatus_WantCreate)
211 {
212 // Create and upload new texture to graphics system
213 //IMGUI_DEBUG_LOG("UpdateTexture #%03d: WantCreate %dx%d\n", tex->UniqueID, tex->Width, tex->Height);
214 IM_ASSERT(tex->TexID == ImTextureID_Invalid && tex->BackendUserData == nullptr);
215 IM_ASSERT(tex->Format == ImTextureFormat_RGBA32);
216
217 // Create texture
218 // (Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling)
219 SDL_Texture* sdl_texture = SDL_CreateTexture(bd->Renderer, SDL_PIXELFORMAT_RGBA32, SDL_TEXTUREACCESS_STATIC, tex->Width, tex->Height);
220 IM_ASSERT(sdl_texture != nullptr && "Backend failed to create texture!");
221 SDL_UpdateTexture(sdl_texture, nullptr, tex->GetPixels(), tex->GetPitch());
222 SDL_SetTextureBlendMode(sdl_texture, SDL_BLENDMODE_BLEND);
223 SDL_SetTextureScaleMode(sdl_texture, SDL_ScaleModeLinear);
224
225 // Store identifiers
226 tex->SetTexID((ImTextureID)(intptr_t)sdl_texture);
227 tex->SetStatus(ImTextureStatus_OK);
228 }
229 else if (tex->Status == ImTextureStatus_WantUpdates)
230 {
231 // Update selected blocks. We only ever write to textures regions which have never been used before!
232 // This backend choose to use tex->Updates[] but you can use tex->UpdateRect to upload a single region.
233 SDL_Texture* sdl_texture = (SDL_Texture*)(intptr_t)tex->TexID;
234 for (ImTextureRect& r : tex->Updates)
235 {
236 SDL_Rect sdl_r = { r.x, r.y, r.w, r.h };
237 SDL_UpdateTexture(sdl_texture, &sdl_r, tex->GetPixelsAt(r.x, r.y), tex->GetPitch());
238 }
239 tex->SetStatus(ImTextureStatus_OK);
240 }
241 else if (tex->Status == ImTextureStatus_WantDestroy)
242 {
243 if (tex->TexID != ImTextureID_Invalid)
244 if (SDL_Texture* sdl_texture = (SDL_Texture*)(intptr_t)tex->TexID)
245 SDL_DestroyTexture(sdl_texture);
246
247 // Clear identifiers and mark as destroyed (in order to allow e.g. calling InvalidateDeviceObjects while running)
248 tex->SetTexID(ImTextureID_Invalid);
249 tex->SetStatus(ImTextureStatus_Destroyed);
250 }
251}
252
253void ImGui_ImplSDLRenderer2_CreateDeviceObjects()
254{
255}
256
257void ImGui_ImplSDLRenderer2_DestroyDeviceObjects()
258{
259 // Destroy all textures
260 for (ImTextureData* tex : ImGui::GetPlatformIO().Textures)
261 if (tex->RefCount == 1)
262 {
263 tex->SetStatus(ImTextureStatus_WantDestroy);
264 ImGui_ImplSDLRenderer2_UpdateTexture(tex);
265 }
266}
267
268bool ImGui_ImplSDLRenderer2_Init(SDL_Renderer* renderer)
269{
270 ImGuiIO& io = ImGui::GetIO();
271 IMGUI_CHECKVERSION();
272 IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
273 IM_ASSERT(renderer != nullptr && "SDL_Renderer not initialized!");
274
275 // Setup backend capabilities flags
276 ImGui_ImplSDLRenderer2_Data* bd = IM_NEW(ImGui_ImplSDLRenderer2_Data)();
277 io.BackendRendererUserData = (void*)bd;
278 io.BackendRendererName = "imgui_impl_sdlrenderer2";
279 io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset; // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
280 io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures; // We can honor ImGuiPlatformIO::Textures[] requests during render.
281
282 ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
283 platform_io.DrawCallback_ResetRenderState = ImGui_ImplSDLRenderer2_DrawCallback_ResetRenderState;
284
285 bd->Renderer = renderer;
286
287 return true;
288}
289
290void ImGui_ImplSDLRenderer2_Shutdown()
291{
292 ImGui_ImplSDLRenderer2_Data* bd = ImGui_ImplSDLRenderer2_GetBackendData();
293 IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
294 ImGuiIO& io = ImGui::GetIO();
295 ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
296
297 ImGui_ImplSDLRenderer2_DestroyDeviceObjects();
298
299 io.BackendRendererName = nullptr;
300 io.BackendRendererUserData = nullptr;
301 io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
302 platform_io.ClearRendererHandlers();
303 IM_DELETE(bd);
304}
305
306//-----------------------------------------------------------------------------
307
308#if defined(__clang__)
309#pragma clang diagnostic pop
310#endif
311
312#endif // #ifndef IMGUI_DISABLE