// ImGui SDL2 binding with OpenGL (legacy, fixed pipeline) // (SDL is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan graphics context creation, etc.) // Implemented features: // [X] User texture binding. Cast 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID in imgui.cpp. // **DO NOT USE THIS CODE IF YOUR CODE/ENGINE IS USING MODERN OPENGL (SHADERS, VBO, VAO, etc.)** // **Prefer using the code in the sdl_opengl3_example/ folder** // 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. // You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this. // If you use this binding you'll need to call 4 functions: ImGui_ImplXXXX_Init(), ImGui_ImplXXXX_NewFrame(), ImGui::Render() and ImGui_ImplXXXX_Shutdown(). // If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp. // https://github.com/ocornut/imgui #include <SDL.h> #include <SDL_syswm.h> #include <SDL_opengl.h> #include "imgui.h" #include "imgui_impl_sdl_gl2.h" // Data static Uint64 g_Time = 0; static bool g_MousePressed[3] = { false, false, false }; static GLuint g_FontTexture = 0; // This is the main rendering function that you have to implement and provide to ImGui (via setting up 'RenderDrawListsFn' in the ImGuiIO structure) // Note that this implementation is little overcomplicated because we are saving/setting up/restoring every OpenGL state explicitly, in order to be able to run within any OpenGL engine that doesn't do so. // If text or lines are blurry when integrating ImGui in your engine: in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f) void ImGui_ImplSdlGL2_RenderDrawLists(ImDrawData* draw_data) { // Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates) ImGuiIO& io = ImGui::GetIO(); int fb_width = (int)(io.DisplaySize.x * io.DisplayFramebufferScale.x); int fb_height = (int)(io.DisplaySize.y * io.DisplayFramebufferScale.y); if (fb_width == 0 || fb_height == 0) return; draw_data->ScaleClipRects(io.DisplayFramebufferScale); // We are using the OpenGL fixed pipeline to make the example code simpler to read! // Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers, polygon fill. 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); glPushAttrib(GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT | GL_TRANSFORM_BIT); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glDisable(GL_CULL_FACE); glDisable(GL_DEPTH_TEST); glEnable(GL_SCISSOR_TEST); glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glEnableClientState(GL_COLOR_ARRAY); glEnable(GL_TEXTURE_2D); glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound // Setup viewport, orthographic projection matrix glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height); glMatrixMode(GL_PROJECTION); glPushMatrix(); glLoadIdentity(); glOrtho(0.0f, io.DisplaySize.x, io.DisplaySize.y, 0.0f, -1.0f, +1.0f); glMatrixMode(GL_MODELVIEW); glPushMatrix(); glLoadIdentity(); // 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) { pcmd->UserCallback(cmd_list, pcmd); } else { glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->TextureId); glScissor((int)pcmd->ClipRect.x, (int)(fb_height - pcmd->ClipRect.w), (int)(pcmd->ClipRect.z - pcmd->ClipRect.x), (int)(pcmd->ClipRect.w - pcmd->ClipRect.y)); glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer); } idx_buffer += pcmd->ElemCount; } } // Restore modified 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, last_polygon_mode[0]); glPolygonMode(GL_BACK, 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]); } static const char* ImGui_ImplSdlGL2_GetClipboardText(void*) { return SDL_GetClipboardText(); } static void ImGui_ImplSdlGL2_SetClipboardText(void*, const char* text) { SDL_SetClipboardText(text); } // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs. // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application. // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application. // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags. bool ImGui_ImplSdlGL2_ProcessEvent(SDL_Event* event) { ImGuiIO& io = ImGui::GetIO(); switch (event->type) { case SDL_MOUSEWHEEL: { if (event->wheel.x > 0) io.MouseWheelH += 1; if (event->wheel.x < 0) io.MouseWheelH -= 1; if (event->wheel.y > 0) io.MouseWheel += 1; if (event->wheel.y < 0) io.MouseWheel -= 1; return true; } case SDL_MOUSEBUTTONDOWN: { if (event->button.button == SDL_BUTTON_LEFT) g_MousePressed[0] = true; if (event->button.button == SDL_BUTTON_RIGHT) g_MousePressed[1] = true; if (event->button.button == SDL_BUTTON_MIDDLE) g_MousePressed[2] = true; return true; } case SDL_TEXTINPUT: { io.AddInputCharactersUTF8(event->text.text); return true; } case SDL_KEYDOWN: case SDL_KEYUP: { int key = event->key.keysym.scancode; IM_ASSERT(key >= 0 && key < IM_ARRAYSIZE(io.KeysDown)); io.KeysDown[key] = (event->type == SDL_KEYDOWN); io.KeyShift = ((SDL_GetModState() & KMOD_SHIFT) != 0); io.KeyCtrl = ((SDL_GetModState() & KMOD_CTRL) != 0); io.KeyAlt = ((SDL_GetModState() & KMOD_ALT) != 0); io.KeySuper = ((SDL_GetModState() & KMOD_GUI) != 0); return true; } } return false; } bool ImGui_ImplSdlGL2_CreateDeviceObjects() { // Build texture atlas ImGuiIO& io = ImGui::GetIO(); unsigned char* pixels; int width, height; io.Fonts->GetTexDataAsAlpha8(&pixels, &width, &height); // Upload texture to graphics system GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture); glGenTextures(1, &g_FontTexture); glBindTexture(GL_TEXTURE_2D, g_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_ALPHA, width, height, 0, GL_ALPHA, GL_UNSIGNED_BYTE, pixels); // Store our identifier io.Fonts->TexID = (void *)(intptr_t)g_FontTexture; // Restore state glBindTexture(GL_TEXTURE_2D, last_texture); return true; } void ImGui_ImplSdlGL2_InvalidateDeviceObjects() { if (g_FontTexture) { glDeleteTextures(1, &g_FontTexture); ImGui::GetIO().Fonts->TexID = 0; g_FontTexture = 0; } } bool ImGui_ImplSdlGL2_Init(SDL_Window* window) { // Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array. ImGuiIO& io = ImGui::GetIO(); io.KeyMap[ImGuiKey_Tab] = SDL_SCANCODE_TAB; io.KeyMap[ImGuiKey_LeftArrow] = SDL_SCANCODE_LEFT; io.KeyMap[ImGuiKey_RightArrow] = SDL_SCANCODE_RIGHT; io.KeyMap[ImGuiKey_UpArrow] = SDL_SCANCODE_UP; io.KeyMap[ImGuiKey_DownArrow] = SDL_SCANCODE_DOWN; io.KeyMap[ImGuiKey_PageUp] = SDL_SCANCODE_PAGEUP; io.KeyMap[ImGuiKey_PageDown] = SDL_SCANCODE_PAGEDOWN; io.KeyMap[ImGuiKey_Home] = SDL_SCANCODE_HOME; io.KeyMap[ImGuiKey_End] = SDL_SCANCODE_END; io.KeyMap[ImGuiKey_Insert] = SDL_SCANCODE_INSERT; io.KeyMap[ImGuiKey_Delete] = SDL_SCANCODE_DELETE; io.KeyMap[ImGuiKey_Backspace] = SDL_SCANCODE_BACKSPACE; io.KeyMap[ImGuiKey_Enter] = SDL_SCANCODE_RETURN; io.KeyMap[ImGuiKey_Escape] = SDL_SCANCODE_ESCAPE; io.KeyMap[ImGuiKey_A] = SDL_SCANCODE_A; io.KeyMap[ImGuiKey_C] = SDL_SCANCODE_C; io.KeyMap[ImGuiKey_V] = SDL_SCANCODE_V; io.KeyMap[ImGuiKey_X] = SDL_SCANCODE_X; io.KeyMap[ImGuiKey_Y] = SDL_SCANCODE_Y; io.KeyMap[ImGuiKey_Z] = SDL_SCANCODE_Z; io.RenderDrawListsFn = ImGui_ImplSdlGL2_RenderDrawLists; // Alternatively you can set this to NULL and call ImGui::GetDrawData() after ImGui::Render() to get the same ImDrawData pointer. io.SetClipboardTextFn = ImGui_ImplSdlGL2_SetClipboardText; io.GetClipboardTextFn = ImGui_ImplSdlGL2_GetClipboardText; io.ClipboardUserData = NULL; #ifdef _WIN32 SDL_SysWMinfo wmInfo; SDL_VERSION(&wmInfo.version); SDL_GetWindowWMInfo(window, &wmInfo); io.ImeWindowHandle = wmInfo.info.win.window; #else (void)window; #endif return true; } void ImGui_ImplSdlGL2_Shutdown() { ImGui_ImplSdlGL2_InvalidateDeviceObjects(); ImGui::Shutdown(); } void ImGui_ImplSdlGL2_NewFrame(SDL_Window *window) { if (!g_FontTexture) ImGui_ImplSdlGL2_CreateDeviceObjects(); ImGuiIO& io = ImGui::GetIO(); // Setup display size (every frame to accommodate for window resizing) int w, h; int display_w, display_h; SDL_GetWindowSize(window, &w, &h); SDL_GL_GetDrawableSize(window, &display_w, &display_h); io.DisplaySize = ImVec2((float)w, (float)h); io.DisplayFramebufferScale = ImVec2(w > 0 ? ((float)display_w / w) : 0, h > 0 ? ((float)display_h / h) : 0); // Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution) static Uint64 frequency = SDL_GetPerformanceFrequency(); Uint64 current_time = SDL_GetPerformanceCounter(); io.DeltaTime = g_Time > 0 ? (float)((double)(current_time - g_Time) / frequency) : (float)(1.0f / 60.0f); g_Time = current_time; // Setup mouse inputs (we already got mouse wheel, keyboard keys & characters from our event handler) int mx, my; Uint32 mouse_buttons = SDL_GetMouseState(&mx, &my); io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX); io.MouseDown[0] = g_MousePressed[0] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_LEFT)) != 0; // If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame. io.MouseDown[1] = g_MousePressed[1] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_RIGHT)) != 0; io.MouseDown[2] = g_MousePressed[2] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_MIDDLE)) != 0; g_MousePressed[0] = g_MousePressed[1] = g_MousePressed[2] = false; // We need to use SDL_CaptureMouse() to easily retrieve mouse coordinates outside of the client area. This is only supported from SDL 2.0.4 (released Jan 2016) #if (SDL_MAJOR_VERSION >= 2) && (SDL_MINOR_VERSION >= 0) && (SDL_PATCHLEVEL >= 4) if ((SDL_GetWindowFlags(window) & (SDL_WINDOW_MOUSE_FOCUS | SDL_WINDOW_MOUSE_CAPTURE)) != 0) io.MousePos = ImVec2((float)mx, (float)my); bool any_mouse_button_down = false; for (int n = 0; n < IM_ARRAYSIZE(io.MouseDown); n++) any_mouse_button_down |= io.MouseDown[n]; if (any_mouse_button_down && (SDL_GetWindowFlags(window) & SDL_WINDOW_MOUSE_CAPTURE) == 0) SDL_CaptureMouse(SDL_TRUE); if (!any_mouse_button_down && (SDL_GetWindowFlags(window) & SDL_WINDOW_MOUSE_CAPTURE) != 0) SDL_CaptureMouse(SDL_FALSE); #else if ((SDL_GetWindowFlags(window) & SDL_WINDOW_INPUT_FOCUS) != 0) io.MousePos = ImVec2((float)mx, (float)my); #endif // Hide OS mouse cursor if ImGui is drawing it SDL_ShowCursor(io.MouseDrawCursor ? 0 : 1); // Start the frame. This call will update the io.WantCaptureMouse, io.WantCaptureKeyboard flag that you can use to dispatch inputs (or not) to your application. ImGui::NewFrame(); }