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I am learning OpenGL by glfw3 lib and I am using imgui to make a interesting application.
However, I can not render what I want in a imgui window.

I searched google and get below link:

  1. Render in a imGui Window
  2. How can I render an OpenGL scene into an ImGui window?

I tried about two days and I have rendered a triangle in a imgui window.
However, when I try to render content as this link(Tutorial and Code) shows me.
The box in my imgui window will not spin! It is a stationary photo.
What's wrong with my code?

#define __abc__is a value to test.
Xhader.h just is the header file in the tutorial, also .vs and .fs files.
The only difference is the tutorial uses glad.h and I use glew.h.

#define __abc__ #define STB_IMAGE_IMPLEMENTATION #include <iostream> #include <GL/glew.h> #include <GLFW/glfw3.h> #include <stb_image.h> #include <glm/glm.hpp> #include <glm/gtc/matrix_transform.hpp> #include <glm/gtc/type_ptr.hpp> #include "imgui.h" #include "imgui_impl_glfw.h" #include "imgui_impl_opengl3.h" #include "Xhader.h" void framebuffer_size_callback(GLFWwindow* window, int width, int height); void processInput(GLFWwindow* window); GLFWwindow* Proinit(); void imguiSetup(GLFWwindow* window); // settings const unsigned int SCR_WIDTH = 800; const unsigned int SCR_HEIGHT = 600; int main() { GLFWwindow* window = Proinit(); imguiSetup(window); int view3d_width = 100; int view3d_height = 200; // configure global opengl state // ----------------------------- glEnable(GL_DEPTH_TEST); // build and compile our shader zprogram // ------------------------------------ Xhader ourShader("shader/vs.txt", "shader/fs.txt"); // set up vertex data (and buffer(s)) and configure vertex attributes // ------------------------------------------------------------------ float vertices[] = { -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, 0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 0.5f, 0.5f, -0.5f, 1.0f, 1.0f, -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.5f, 0.5f, 0.5f, 1.0f, 1.0f, 0.5f, 0.5f, 0.5f, 1.0f, 1.0f, -0.5f, 0.5f, 0.5f, 0.0f, 1.0f, -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, -0.5f, 0.5f, 0.5f, 1.0f, 0.0f, -0.5f, 0.5f, -0.5f, 1.0f, 1.0f, -0.5f, -0.5f, -0.5f, 0.0f, 1.0f, -0.5f, -0.5f, -0.5f, 0.0f, 1.0f, -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, -0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 0.5f, -0.5f, -0.5f, 0.0f, 1.0f, 0.5f, -0.5f, -0.5f, 0.0f, 1.0f, 0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 0.5f, 0.5f, 0.5f, 1.0f, 0.0f, -0.5f, -0.5f, -0.5f, 0.0f, 1.0f, 0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.5f, -0.5f, 0.5f, 1.0f, 0.0f, -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, -0.5f, -0.5f, -0.5f, 0.0f, 1.0f, -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.5f, 0.5f, -0.5f, 1.0f, 1.0f, 0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.5f, 0.5f, 0.5f, 1.0f, 0.0f, -0.5f, 0.5f, 0.5f, 0.0f, 0.0f, -0.5f, 0.5f, -0.5f, 0.0f, 1.0f }; GLuint VBO; glGenBuffers(1, &VBO); glBindBuffer(GL_ARRAY_BUFFER, VBO); glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); GLuint VAO; glGenVertexArrays(1, &VAO); glBindVertexArray(VAO); glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0); glEnableVertexAttribArray(0); glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float))); glEnableVertexAttribArray(1); //--------------------------------------- FBO -----------------------------// #ifdef __abc__ unsigned int fbo; glGenFramebuffers(1, &fbo); glBindFramebuffer(GL_FRAMEBUFFER, fbo); GLuint TOF; glGenTextures(1, &TOF); glBindTexture(GL_TEXTURE_2D, TOF); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 400, 300, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); #else ; #endif // load and create a texture // ------------------------- unsigned int texture1, texture2; // texture 1 // --------- glGenTextures(1, &texture1); glBindTexture(GL_TEXTURE_2D, texture1); // set the texture wrapping parameters glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); // set texture filtering parameters glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // load image, create texture and generate mipmaps int width, height, nrChannels; stbi_set_flip_vertically_on_load(true); // tell stb_image.h to flip loaded texture's on the y-axis. std::string s1 = "resources/textures/container.jpg"; std::string s2 = "resources/textures/awesomeface.png"; unsigned char* data = stbi_load(s1.c_str(), &width, &height, &nrChannels, 0); if (data) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data); glGenerateMipmap(GL_TEXTURE_2D); } else { std::cout << "Failed to load texture" << std::endl; } stbi_image_free(data); // texture 2 // --------- glGenTextures(1, &texture2); glBindTexture(GL_TEXTURE_2D, texture2); // set the texture wrapping parameters glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); // set texture filtering parameters glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // load image, create texture and generate mipmaps data = stbi_load(s2.c_str(), &width, &height, &nrChannels, 0); if (data) { // note that the awesomeface.png has transparency and thus an alpha channel, so make sure to tell OpenGL the data type is of GL_RGBA glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data); glGenerateMipmap(GL_TEXTURE_2D); } else { std::cout << "Failed to load texture" << std::endl; } stbi_image_free(data); // tell opengl for each sampler to which texture unit it belongs to (only has to be done once) // ------------------------------------------------------------------------------------------- ourShader.use(); ourShader.setInt("texture1", 0); ourShader.setInt("texture2", 1); // render loop // ----------- while (!glfwWindowShouldClose(window)) { #ifdef __abc__ glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, TOF, 0); #endif if (glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE) { std::cout << "FRAMEBUFFER SUCCESS" << std::endl; glViewport(0, 0, 400, 300); // render // ------ glClearColor(0.2f, 0.3f, 0.3f, 1.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // also clear the depth buffer now! // bind textures on corresponding texture units glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture1); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture2); // activate shader ourShader.use(); // create transformations glm::mat4 model = glm::mat4(1.0f); // make sure to initialize matrix to identity matrix first glm::mat4 view = glm::mat4(1.0f); glm::mat4 projection = glm::mat4(1.0f); float time = (float)glfwGetTime(); std::cout << time << std::endl; model = glm::rotate(model,time , glm::vec3(0.5f, 1.0f, 0.0f)); view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f)); projection = glm::perspective(glm::radians(45.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f); // retrieve the matrix uniform locations unsigned int modelLoc = glGetUniformLocation(ourShader.ID, "model"); unsigned int viewLoc = glGetUniformLocation(ourShader.ID, "view"); // pass them to the shaders (3 different ways) glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model)); glUniformMatrix4fv(viewLoc, 1, GL_FALSE, &view[0][0]); // note: currently we set the projection matrix each frame, //but since the projection matrix rarely changes it's often best practice //to set it outside the main loop only once. ourShader.setMat4("projection", projection); // render box glBindVertexArray(VAO); glDrawArrays(GL_TRIANGLES, 0, 36); #ifdef __abc__ glBindFramebuffer(GL_FRAMEBUFFER, 0); #endif } else { std::cout << "ERROR::FRAMEBUFFER:: Framebuffer is not complete!" << std::endl; } #ifdef __abc__ // Start the Dear ImGui frame ImGui_ImplOpenGL3_NewFrame(); ImGui_ImplGlfw_NewFrame(); ImGui::NewFrame(); bool View_3D = true; if (View_3D) { ImGui::Begin("3D View", &View_3D); view3d_height = ImGui::GetWindowSize().x; view3d_width = ImGui::GetWindowSize().y; ImVec2 pos = ImGui::GetCursorScreenPos(); ImGui::GetWindowDrawList()->AddImage( (void*)TOF, ImVec2(ImGui::GetCursorScreenPos()), ImVec2(ImGui::GetCursorScreenPos().x + ImGui::GetWindowSize().x - 15, ImGui::GetCursorScreenPos().y + ImGui::GetWindowSize().y - 35), ImVec2(0, 1), ImVec2(1, 0) ); ImGui::End(); } // input // ----- processInput(window); ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f); // render ImGui::Render(); int display_w, display_h; glfwGetFramebufferSize(window, &display_w, &display_h); glViewport(0, 0, display_w, display_h); glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w); glClear(GL_COLOR_BUFFER_BIT); ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData()); #endif // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.) // ------------------------------------------------------------------------------- glfwSwapBuffers(window); glfwPollEvents(); } // optional: de-allocate all resources once they've outlived their purpose: // ------------------------------------------------------------------------ glDeleteVertexArrays(1, &VAO); glDeleteBuffers(1, &VBO); // glfw: terminate, clearing all previously allocated GLFW resources. // ------------------------------------------------------------------ glfwTerminate(); return 0; } // process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly // --------------------------------------------------------------------------------------------------------- void processInput(GLFWwindow* window) { if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) glfwSetWindowShouldClose(window, true); } // glfw: whenever the window size changed (by OS or user resize) this callback function executes // --------------------------------------------------------------------------------------------- void framebuffer_size_callback(GLFWwindow* window, int width, int height) { // make sure the viewport matches the new window dimensions; note that width and // height will be significantly larger than specified on retina displays. glViewport(0, 0, width, height); } GLFWwindow* Proinit() { //glfwSetErrorCallback(glfw_error_callback); if (!glfwInit()) return (GLFWwindow*)1; #ifdef __APPLE__ // GL 3.2 + GLSL 150 const char* glsl_version = "#version 150"; glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // 3.2+ only glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // Required on Mac #else const char* glsl_version = "#version 130"; glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); //glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); // 3.2+ only //glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // 3.0+ only #endif GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "Shader3D", NULL, NULL); if (window == NULL) { std::cout << "Failed to create GLFW window" << std::endl; glfwTerminate(); return (GLFWwindow*)-1; } glfwMakeContextCurrent(window); //glfwSwapInterval(1); // Enable vsync //glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); #if defined(IMGUI_IMPL_OPENGL_LOADER_GLEW) bool err = glewInit() != GLEW_OK; #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD) bool err = gladLoadGL() == 0; #else bool err = false; #endif if (err) { fprintf(stderr, "Failed to initialize OpenGL loader!\n"); return (GLFWwindow*)1; } return window; } void imguiSetup(GLFWwindow* window) { // Setup Dear ImGui context IMGUI_CHECKVERSION(); ImGui::CreateContext(); ImGuiIO& io = ImGui::GetIO(); (void)io; //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad; // Enable Gamepad Controls ImGui::StyleColorsDark(); ImGui_ImplGlfw_InitForOpenGL(window, true); //Setup Platform bindings #ifdef __APPLE__ ImGui_ImplOpenGL3_Init("#version 150"); //Setup Renderer bindings #else ImGui_ImplOpenGL3_Init("#version 130"); #endif }
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  • \$\begingroup\$ Does it spin if you render directly to the default framebuffer? \$\endgroup\$ Commented Apr 1, 2020 at 16:59
  • \$\begingroup\$ yes, it spin if you use default buffer. \$\endgroup\$ Commented Apr 1, 2020 at 19:18

1 Answer 1

Reset to default
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Move these lines inside the while loop.

unsigned int fbo; glGenFramebuffers(1, &fbo); glBindFramebuffer(GL_FRAMEBUFFER, fbo); GLuint TOF; glGenTextures(1, &TOF); glBindTexture(GL_TEXTURE_2D, TOF); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 400, 300, 0, GL_RGB, GL_UNSIGNED_BYTE, NULL); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

Then once all your rendering is done you have to delete the frame buffer and texture object every time inside the loop.

glDeleteFramebuffers(1, &fbo); glDeleteTextures(1, &TOF);

The idea is for each and every time inside the loop, the frame buffer needs to be created, utilized and the deleted. Other wise the buffer will not refresh.

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