| // 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. |
| // 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 |
| |
| // **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) |
| // 2022-10-11: Using 'nullptr' instead of 'NULL' as per our switch to C++11. |
| // 2021-12-08: OpenGL: Fixed mishandling of the 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" |
| #include "imgui_impl_opengl2.h" |
| #if defined(_MSC_VER) && _MSC_VER <= 1500 // MSVC 2008 or earlier |
| #include <stddef.h> // intptr_t |
| #else |
| #include <stdint.h> // intptr_t |
| #endif |
| |
| // 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(); |
| 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 && "Did you call ImGui_ImplOpenGL2_Init()?"); |
| |
| if (!bd->FontTexture) |
| ImGui_ImplOpenGL2_CreateDeviceObjects(); |
| } |
| |
| 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 + IM_OFFSETOF(ImDrawVert, pos))); |
| glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, uv))); |
| glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_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 |