// dear imgui: Renderer Backend for OpenGL2 (legacy OpenGL, fixed pipeline) // This needs to be used along with a Platform Backend (e.g. GLFW, SDL, Win32, custom..) // Implemented features: // [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID! // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this. // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need. // Learn about Dear ImGui: // - FAQ https://dearimgui.com/faq // - Getting Started https://dearimgui.com/getting-started // - Documentation https://dearimgui.com/docs (same as your local docs/ folder). // - Introduction, links and more at the top of imgui.cpp // **DO NOT USE THIS CODE IF YOUR CODE/ENGINE IS USING MODERN OPENGL (SHADERS, VBO, VAO, etc.)** // **Prefer using the code in imgui_impl_opengl3.cpp** // This code is mostly provided as a reference to learn how ImGui integration works, because it is shorter to read. // If your code is using GL3+ context or any semi modern OpenGL calls, using this is likely to make everything more // complicated, will require your code to reset every single OpenGL attributes to their initial state, and might // confuse your GPU driver. // The GL2 code is unable to reset attributes or even call e.g. "glUseProgram(0)" because they don't exist in that API. // CHANGELOG // (minor and older changes stripped away, please see git history for details) // 2024-06-28: OpenGL: ImGui_ImplOpenGL2_NewFrame() recreates font texture if it has been destroyed by ImGui_ImplOpenGL2_DestroyFontsTexture(). (#7748) // 2022-10-11: Using 'nullptr' instead of 'NULL' as per our switch to C++11. // 2021-12-08: OpenGL: Fixed mishandling of the ImDrawCmd::IdxOffset field! This is an old bug but it never had an effect until some internal rendering changes in 1.86. // 2021-06-29: Reorganized backend to pull data from a single structure to facilitate usage with multiple-contexts (all g_XXXX access changed to bd->XXXX). // 2021-05-19: OpenGL: Replaced direct access to ImDrawCmd::TextureId with a call to ImDrawCmd::GetTexID(). (will become a requirement) // 2021-01-03: OpenGL: Backup, setup and restore GL_SHADE_MODEL state, disable GL_STENCIL_TEST and disable GL_NORMAL_ARRAY client state to increase compatibility with legacy OpenGL applications. // 2020-01-23: OpenGL: Backup, setup and restore GL_TEXTURE_ENV to increase compatibility with legacy OpenGL applications. // 2019-04-30: OpenGL: Added support for special ImDrawCallback_ResetRenderState callback to reset render state. // 2019-02-11: OpenGL: Projecting clipping rectangles correctly using draw_data->FramebufferScale to allow multi-viewports for retina display. // 2018-11-30: Misc: Setting up io.BackendRendererName so it can be displayed in the About Window. // 2018-08-03: OpenGL: Disabling/restoring GL_LIGHTING and GL_COLOR_MATERIAL to increase compatibility with legacy OpenGL applications. // 2018-06-08: Misc: Extracted imgui_impl_opengl2.cpp/.h away from the old combined GLFW/SDL+OpenGL2 examples. // 2018-06-08: OpenGL: Use draw_data->DisplayPos and draw_data->DisplaySize to setup projection matrix and clipping rectangle. // 2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed ImGui_ImplOpenGL2_RenderDrawData() in the .h file so you can call it yourself. // 2017-09-01: OpenGL: Save and restore current polygon mode. // 2016-09-10: OpenGL: Uploading font texture as RGBA32 to increase compatibility with users shaders (not ideal). // 2016-09-05: OpenGL: Fixed save and restore of current scissor rectangle. #include "imgui.h" #ifndef IMGUI_DISABLE #include "imgui_impl_opengl2.h" #include <stdint.h> // intptr_t // Clang/GCC warnings with -Weverything #if defined(__clang__) #pragma clang diagnostic push #pragma clang diagnostic ignored "-Wunused-macros" // warning: macro is not used #pragma clang diagnostic ignored "-Wnonportable-system-include-path" #endif // Include OpenGL header (without an OpenGL loader) requires a bit of fiddling #if defined(_WIN32) && !defined(APIENTRY) #define APIENTRY __stdcall // It is customary to use APIENTRY for OpenGL function pointer declarations on all platforms. Additionally, the Windows OpenGL header needs APIENTRY. #endif #if defined(_WIN32) && !defined(WINGDIAPI) #define WINGDIAPI __declspec(dllimport) // Some Windows OpenGL headers need this #endif #if defined(__APPLE__) #define GL_SILENCE_DEPRECATION #include <OpenGL/gl.h> #else #include <GL/gl.h> #endif struct ImGui_ImplOpenGL2_Data { GLuint FontTexture; ImGui_ImplOpenGL2_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_ImplOpenGL2_Data* ImGui_ImplOpenGL2_GetBackendData() { return ImGui::GetCurrentContext() ? (ImGui_ImplOpenGL2_Data*)ImGui::GetIO().BackendRendererUserData : nullptr; } // Functions bool ImGui_ImplOpenGL2_Init() { ImGuiIO& io = ImGui::GetIO(); IMGUI_CHECKVERSION(); IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!"); // Setup backend capabilities flags ImGui_ImplOpenGL2_Data* bd = IM_NEW(ImGui_ImplOpenGL2_Data)(); io.BackendRendererUserData = (void*)bd; io.BackendRendererName = "imgui_impl_opengl2"; return true; } void ImGui_ImplOpenGL2_Shutdown() { ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData(); IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?"); ImGuiIO& io = ImGui::GetIO(); ImGui_ImplOpenGL2_DestroyDeviceObjects(); io.BackendRendererName = nullptr; io.BackendRendererUserData = nullptr; IM_DELETE(bd); } void ImGui_ImplOpenGL2_NewFrame() { ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData(); IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplOpenGL2_Init()?"); if (!bd->FontTexture) ImGui_ImplOpenGL2_CreateDeviceObjects(); if (!bd->FontTexture) ImGui_ImplOpenGL2_CreateFontsTexture(); } static void ImGui_ImplOpenGL2_SetupRenderState(ImDrawData* draw_data, int fb_width, int fb_height) { // Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers, polygon fill. glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); //glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA); // In order to composite our output buffer we need to preserve alpha glDisable(GL_CULL_FACE); glDisable(GL_DEPTH_TEST); glDisable(GL_STENCIL_TEST); glDisable(GL_LIGHTING); glDisable(GL_COLOR_MATERIAL); glEnable(GL_SCISSOR_TEST); glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glEnableClientState(GL_COLOR_ARRAY); glDisableClientState(GL_NORMAL_ARRAY); glEnable(GL_TEXTURE_2D); glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glShadeModel(GL_SMOOTH); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); // If you are using this code with non-legacy OpenGL header/contexts (which you should not, prefer using imgui_impl_opengl3.cpp!!), // you may need to backup/reset/restore other state, e.g. for current shader using the commented lines below. // (DO NOT MODIFY THIS FILE! Add the code in your calling function) // GLint last_program; // glGetIntegerv(GL_CURRENT_PROGRAM, &last_program); // glUseProgram(0); // ImGui_ImplOpenGL2_RenderDrawData(...); // glUseProgram(last_program) // There are potentially many more states you could need to clear/setup that we can't access from default headers. // e.g. glBindBuffer(GL_ARRAY_BUFFER, 0), glDisable(GL_TEXTURE_CUBE_MAP). // Setup viewport, orthographic projection matrix // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps. glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height); glMatrixMode(GL_PROJECTION); glPushMatrix(); glLoadIdentity(); glOrtho(draw_data->DisplayPos.x, draw_data->DisplayPos.x + draw_data->DisplaySize.x, draw_data->DisplayPos.y + draw_data->DisplaySize.y, draw_data->DisplayPos.y, -1.0f, +1.0f); glMatrixMode(GL_MODELVIEW); glPushMatrix(); glLoadIdentity(); } // OpenGL2 Render function. // Note that this implementation is little overcomplicated because we are saving/setting up/restoring every OpenGL state explicitly. // This is in order to be able to run within an OpenGL engine that doesn't do so. void ImGui_ImplOpenGL2_RenderDrawData(ImDrawData* draw_data) { // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates) int fb_width = (int)(draw_data->DisplaySize.x * draw_data->FramebufferScale.x); int fb_height = (int)(draw_data->DisplaySize.y * draw_data->FramebufferScale.y); if (fb_width == 0 || fb_height == 0) return; // Backup GL state GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture); GLint last_polygon_mode[2]; glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode); GLint last_viewport[4]; glGetIntegerv(GL_VIEWPORT, last_viewport); GLint last_scissor_box[4]; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box); GLint last_shade_model; glGetIntegerv(GL_SHADE_MODEL, &last_shade_model); GLint last_tex_env_mode; glGetTexEnviv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, &last_tex_env_mode); glPushAttrib(GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT | GL_TRANSFORM_BIT); // Setup desired GL state ImGui_ImplOpenGL2_SetupRenderState(draw_data, fb_width, fb_height); // Will project scissor/clipping rectangles into framebuffer space ImVec2 clip_off = draw_data->DisplayPos; // (0,0) unless using multi-viewports ImVec2 clip_scale = draw_data->FramebufferScale; // (1,1) unless using retina display which are often (2,2) // Render command lists 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; glVertexPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + offsetof(ImDrawVert, pos))); glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + offsetof(ImDrawVert, uv))); glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + offsetof(ImDrawVert, col))); 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_ImplOpenGL2_SetupRenderState(draw_data, fb_width, fb_height); 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_max.x <= clip_min.x || clip_max.y <= clip_min.y) continue; // Apply scissor/clipping rectangle (Y is inverted in OpenGL) glScissor((int)clip_min.x, (int)((float)fb_height - clip_max.y), (int)(clip_max.x - clip_min.x), (int)(clip_max.y - clip_min.y)); // Bind texture, Draw glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->GetTexID()); glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer + pcmd->IdxOffset); } } } // Restore modified GL state glDisableClientState(GL_COLOR_ARRAY); glDisableClientState(GL_TEXTURE_COORD_ARRAY); glDisableClientState(GL_VERTEX_ARRAY); glBindTexture(GL_TEXTURE_2D, (GLuint)last_texture); glMatrixMode(GL_MODELVIEW); glPopMatrix(); glMatrixMode(GL_PROJECTION); glPopMatrix(); glPopAttrib(); glPolygonMode(GL_FRONT, (GLenum)last_polygon_mode[0]); glPolygonMode(GL_BACK, (GLenum)last_polygon_mode[1]); glViewport(last_viewport[0], last_viewport[1], (GLsizei)last_viewport[2], (GLsizei)last_viewport[3]); glScissor(last_scissor_box[0], last_scissor_box[1], (GLsizei)last_scissor_box[2], (GLsizei)last_scissor_box[3]); glShadeModel(last_shade_model); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, last_tex_env_mode); } bool ImGui_ImplOpenGL2_CreateFontsTexture() { // Build texture atlas ImGuiIO& io = ImGui::GetIO(); ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData(); 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) GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture); glGenTextures(1, &bd->FontTexture); glBindTexture(GL_TEXTURE_2D, bd->FontTexture); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glPixelStorei(GL_UNPACK_ROW_LENGTH, 0); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels); // Store our identifier io.Fonts->SetTexID((ImTextureID)(intptr_t)bd->FontTexture); // Restore state glBindTexture(GL_TEXTURE_2D, last_texture); return true; } void ImGui_ImplOpenGL2_DestroyFontsTexture() { ImGuiIO& io = ImGui::GetIO(); ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData(); if (bd->FontTexture) { glDeleteTextures(1, &bd->FontTexture); io.Fonts->SetTexID(0); bd->FontTexture = 0; } } bool ImGui_ImplOpenGL2_CreateDeviceObjects() { return ImGui_ImplOpenGL2_CreateFontsTexture(); } void ImGui_ImplOpenGL2_DestroyDeviceObjects() { ImGui_ImplOpenGL2_DestroyFontsTexture(); } //----------------------------------------------------------------------------- #if defined(__clang__) #pragma clang diagnostic pop #endif #endif // #ifndef IMGUI_DISABLE